Tuesday, May 31, 2011

May 31, 2011: Hot, Stormy Start To Summer

Note: As tonight's update focuses on tomorrow's severe weather risk, the 5-Day Forecast page was not updated. An afternoon update will be posted tomorrow, as well as storm updates in the late afternoon if needed.

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After warm temperatures yesterday across the area, a weak back door cold front moved in from the north, but the impact of this front was underestimated. Despite a sea breeze in the afternoon lowering temperatures, high temperatures still reached the lower to upper 80s were still observed in Long Island/southern Connecticut, upper 80s in NYC, and upper 80s to lower 90s in northern NJ and SE NY. Yesterday, all of the models were in agreement showing colder temperatures, with an ESE wind and a back door cold front to the west supporting this, but only this morning the models suddenly changed to show warmer temperatures across the area.

The back door cold front will move east and out of the area tonight as a warm front, with hot temperatures once again tomorrow. With the main cold front moving towards the area, however, thunderstorms will be a risk tomorrow, and it is possible that tomorrow may bring the area's first significant severe weather outbreak of the year.


Tomorrow's Outlook:

Mainly cloudy skies along with some fog are expected in the morning across the area. With the warm front moving through, some showers and thunderstorms are very possible in parts of the NE, potentially including parts of the area, and even another MCS similar to what we saw yesterday morning cannot be ruled out, but most of the storms would stay to our north should there be any activity tomorrow morning.

With the warm front to the east of the area, a southwest wind is expected, which combined with sunshine in the late morning into the early afternoon hours, will allow temperatures to warm up into the upper 80s to lower 90s from NYC and further west. Temperatures in Long Island and southern Connecticut will range from the mid 70s to mid 80s. With dew points potentially reaching the lower 70s, heat index will reach the lower to potentially mid 90s from NYC and further west.

There is a clear risk of severe weather tomorrow in the region, but how big the risk ends up is uncertain. Most of the models continue to show impressive parameters, with CAPE up to 4000, LI up to -10, and lapse rates up to 7. Bulk shear up to 35-40 knots is expected, which is enough for at least an enhanced 30% risk of severe weather. The higher bulk shear values are to the north of the area, and I placed the area in the southern end of the 30% risk, which extends into New England.

Most models show a risk of severe weather, but the NAM model is the main outlier, consistently showing scenarios where severe weather fails to take place, ranging from storms to the south of the area on its 18z run to morning storms sticking around the area, preventing any formation of storms in New England in its 00z run. Interestingly, it shows very little activity in New England, where the higher risk of severe weather is expected to end up. Even the SREF ensemble mean shows a more supportive set up for severe weather. At this time, I am using the other models, but morning storms in the Northeast and potentially in the area cannot be ruled out, which would limit instability and temperature rise, therefore reducing the severe weather risk.

Thunderstorms are expected to begin forming in the central Northeast around 1-4 PM tomorrow and move towards the east southeast, reaching the area by the late afternoon. Most models place the best risk of precipitation from northern NJ into New England, where I placed a 30% risk, but some thunderstorms are expected south of there as well. Strong wind gusts are the main risk with tomorrow's storms with small-moderate hail also possible, and the risk of a tornado, especially into New England, cannot be ruled out. It is possible that tomorrow ends up drier than expected, with less widespread thunderstorms, which may also reduce the risk of severe weather. For now, I am sticking with a 30% risk area, but should the main model guidance verify, I may upgrade the risk to an enhanced 30% risk. Stay tuned for an update on the storms tomorrow afternoon, along with storm updates in the late afternoon.


Longer Range: Tomorrow night's update will focus more on the longer range, discussing the cool down for Thursday and Friday bringing high temperatures into the mid 70s to lower 80s across the area, followed by slightly warmer temperatures for the weekend which may come along with a rain chance before cooling down again early next week, as we enter a pattern where the biggest heat remains to the south and west of the area with more seasonable temperatures in the area.

Monday, May 30, 2011

May 30, 2011: Severe Weather On Wednesday

Behind the MCS that affected the area this morning, cloud cover cleared across the area, resulting in temperatures quickly rising into the upper 80s to lower 90s west of NYC, mid to upper 80s in NYC, and the upper 70s to mid 80s in Long Island and southern Connecticut, making today the warmest day of the year so far in most of the area. A back door cold front will move through tonight, lowering tomorrow's temperatures, but Wednesday will slightly warm up again ahead of a cold front which may be capable of producing this year's first significant severe weather event in the area.


Tomorrow's Outlook: Colder

When first discussing the heat wave potential for early this week, the expectation was there for a large ridge to move into the region and stick around through Wednesday, producing widespread 90+ degree readings across the region. For most of the region, this is true, especially in the centrla/southern Mid Atlantic where mid to upper 90s were reported today and are expected again tomorrow, but changes in the set up resulted in the warmth being pulled further west, not over the area as originally expected.

The original expectation was for a low pressure just north of the Dakotas moving east/ENE, with a widespread ridge covering the region. Since then, however, the low pressure has trended further west, stronger, and more negatively tilted, pulling in more warmth to the west of the region while a trough near New England pushes more south. This brings a back door cold front through the area, pushing the warmest temperatures to the south and west of the area while bringing an east/ESE wind to the central/eastern parts of the area. As a result, high temperatures tomorrow will be colder, reaching the mid to upper 80s in northern New Jersey, upper 70s to mid 80s in the immediate NYC area, and the lower to upper 70s for Long Island and southern Connecticut with a few lower 80s possible further west towards NYC. Mostly sunny skies are expected with mostly dry conditions, though an isolated shower or thunderstorm cannot be ruled out.


Wednesday: Severe Storms Possible

The back door cold front will move through the area as a warm front on Tuesday night, bringing a southwest wind for Wednesday along with warmer temperatures once again. Even though the ridge will weaken as the cold front approaches, with enough sunshine in the morning and early afternoon hours, NYC and further west will once again reach the upper 80s with some lower 90s possible as well. Long Island and southern Connecticut will slightly warm up as well, with temperatures closer to today's high temperatures.

The models are showing parameters supportive of severe weather, with CAPE up to 3000 and lift index up to -10. Additionally, lapse rates of around 7 are expected. The lack of shear in the area is the main issue, however, with only 30-40 knots of bulk shear expected. With the parameters in place, severe thunderstorms are still possible in the afternoon and evening hours, but the highest risk of severe weather is likely to stay to the north of the area. Stay tuned for more information on Wednesday's severe weather risk.


Late Week And Weekend:

Behind the cold front, a colder air mass will approach, but the coldest temperatures won't arrive immediately behind the front. Thursday will bring slightly colder temperatures, reaching the mid 70s to mid 80s across the area. By Thursday night, clearing skies will take place with a high pressure nearby, which combined with 850 mb temperatures below 10c, may bring low temperatures into the upper 40s for the interior north/westernmost parts of the area on Thursday night.

Friday will bring colder temperatures, in the lower to upper 70s across most of the area with a few lower 80s in the immediate NYC area. Saturday and Sunday will slightly warm up, with mid 80s possible again, before another cool down is possible by early next week. Stay tuned for more information on the longer range.

May 30, 2011 Noon Update

12:00 PM: With this morning's MCS (mesoscale convective system) out of the region, bringing an estimated 1/4 to 3/4 inch of rain from NYC and further west and up to 1/4 inch east of NYC, cloud cover is starting to slowly clear from NYC and further west, allowing temperatures which have been stuck in the 70s across the area to begin rising. Temperatures were already expected to be in the lower to mid 80s from NYC and further west as of 11 AM, showing that today's temperatures will end up below the original forecast.

Partly cloudy skies are expected later this afternoon, with high temperatures reaching the mid to upper 80s from NYC and further west, with a few lower 90s possible in the immediate NYC area. Temperatures will peak in the mid 70s to mid 80s in Long Island and southern Connecticut. Tuesday's highs will be much colder, only reaching the upper 70s to mid 80s in the immediate NYC area with upper 60s to mid 70s further east.


Wednesday's Storms: There have not been any significant changes with the models for Wednesday, with a line of showers and thunderstorms expected to move through in the afternoon and evening hours. The models are still showing supportive severe weather parameters, but bulk shear is still missing. There is enough support for a slight severe weather risk, where I'd go with a low end 30% risk in the area and into southern New England, but this outbreak is unlikely to be as big as the one in Pennsylvania and New York a few days ago.

May 30, 2011 Morning: Surprise Strong Storms

6:55 AM: Yesterday, a long lasting MCS went through southern Michigan, bringing wind damage to that area, before weakening and moving into western NY by the evening. It was expected to weaken and stay to the north of the area, but instead, with instability still in place over the area, the MCS took a turn towards the southeast and unexpectedly strengthened, moving towards the area. Strong thunderstorms moved over northern NJ and southeastern NY over the last 1-2 hours, and are currently entering Long Island. The storms are weakening, but it is impressive how long they have held together until this point, even reaching the area and still bringing strong thunderstorms.

Another update will be posted later this morning, but today's temperature outlook has been lowered across the area, with most of northern NJ now expected to stay in the upper 80s to lower 90s, with the warmest temperatures towards the immediate NYC area. Signs are there for a stronger back door cold front than previously expected, and NYC will struggle into the lower to potentially mid 80s on Tuesday while places east of NYC fail to reach the 80 degree mark, while severe thunderstorms remain a possibility for Wednesday. I will discuss why there is no longer a heat wave potential in the area, as well as Wednesday's severe weather risk, in more details later this morning.


Sunday, May 29, 2011

May 29, 2011: Summer Begins In NYC Area

Note: The 5-Day Forecast will be updated tomorrow morning, and an update discussing tomorrow's conditions and Wednesday's severe weather will be posted as well.

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With a very warm air mass starting to spread into the region from the south central US, today brought warm temperatures into the area, reaching the lower to mid 80s from NYC and further west, and the lower to upper 70s in Long Island and southern Connecticut with a few lower 80s reported as well.

June 1st is the start of meteorological summer, and this year's June 1st will feel like a typical July day. Hot temperatures will enter the area tomorrow, bringing high temperatures into the 90s from NYC and further west, and while temperatures will cool down from NYC and further east on Tuesday due to a weak back door cold front, Wednesday will slightly warm up ahead of a cold front, which may be capable of producing the area's first significant severe weather outbreak of the year.


Memorial Day Outlook: Hot And Humid

**Correction: The date on the graphic should be "5/30", not "5/29".**

A very warm air mass will move into the area tomorrow, with 850 mb temperatures near 20 degrees celsisus. Other than some fog and cloud cover in the morning, clearing skies are expected by the afternoon, which combined with a southwest wind, will allow temperatures to rise into the 90s from NYC and further west. Most areas west of NYC will reach the lower 90s, but some mid 90s are expected as well in parts of the immediate NYC area. Heat index may reach the mid to upper 90s in the immediate NYC area. East of NYC, warm temperatures are expected as well, ranging from the mid-upper 70s along the immediate coast of Long Island to the upper 80s in western Long Island/SW Connecticut.

There is some slight uncertainty with the exact temperatures, and at this time I am going slightly warmer than the model guidance. In addition, there is also the risk of pop up showers and thunderstorms late tomorrow afternoon into the evening hours, and while the storms that do form, if any, should be isolated, any storm that does form may be capable of reaching strong/severe levels. An update will be posted tomorrow morning regarding tomorrow's conditions as well as Wednesday's potential severe weather outbreak.


Tuesday - Thursday: Heat Continues, Severe Weather Risk

A weak back door cold front will move into the area on Tuesday morning, moving in from north to south. This will result in a mostly east wind for the central and eastern parts of the area, bringing in colder temperatures. Temperatures from NYC and further west will still be very warm, in the upper 80s to lower 90s in northern NJ and in the mid to potentially upper 80s in NYC, but east of NYC, temperatures will be colder, reaching the lower 70s to lower 80s. Some models have been suggesting a risk of severe weather on Tuesday, and while it is uncertain at this time, isolated showers and thunderstorms cannot be ruled out, some which may be strong.

As a storm well to the north of the area moves east, the back door cold front will move east again as a warm front, with 850 mb temperatures once again returning into the 18c-20c range. Some sunshine is expected through the afternoon hours, allowing temperatures to warm up once again into the upper 80s to lower 90s from NYC and further west with a southwest wind, bringing warmer temperatures to Long Island/southern Connecticut as well.


Severe Weather Risk: By the late afternoon hours, however, the storm's cold front will approach the area, bringing widespread showers and thunderstorms into the Northeast, generally moving east/ESE. The models are showing extremely high parameters, with the GFS showing CAPE as high as 4000 and LI as low as -12, which can cause large scale severe weather outbreaks if the right conditions are in place. There is a lack of bulk shear, however, which is only expected to reach 30-35 knots. In comparison, the severe storms in Pennsylvania several days ago were generally in the 40-60 knot range.

Regardless of the lack of bulk shear, this cold front is still capable of producing a widespread significant severe weather outbreak. SPC, the Storm Prediction Center, has also noted this potential, starting to do so yesterday by placing a rare Day 5 severe weather risk in the area. At this time, I would place a 30% risk of severe weather in the area, however some changes are still possible. Stay tuned for more information on this severe weather event.


Longer Range: Thursday will still bring temperatures in the mid 70s to mid 80s across the area, but by Friday, a cold air mass will move through. The models have backed away from the significant cold that was shown several days ago, and are now expecting temperatures to mostly drop into the mid 70s to lower 80s across the area for Friday. Next weekend will bring more widespread 80s into the area once again as warmth builds into the region once again.

Saturday, May 28, 2011

May 28, 2011 Morning: Hot Memorial Day

Note: The next update will be posted on Sunday night. The 5-Day Forecast has been updated once again for the entire area.


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The same cold front that brought damaging and deadly severe weather outbreaks from the central US to Pennsylvania/New York state will finally reach the area today with some thunderstorm, but it has significantly weakened over the last two days, and will bring nothing more than scattered showers and thunderstorms from NYC and further west today.

By tomorrow, however, a very warm air mass bringing temperatures today as high as 110 degrees in Texas will begin to spread into the central and eastern United States, bringing hot temperatures on Memorial Day, reaching the mid 90s in parts of the immediate NYC area. A cold front will bring an end to the heat by Wednesday/Thursday, but with the cold front comes a risk of severe weather.




Weekend Outlook:


Scattered showers and thunderstorms are expected today, mostly from NYC and further west. These storms will stay below severe levels. Otherwise, partly to mostly cloudy skies are expected today, with high temperatures in the upper 70s to lower 80s from NYC and further west and the lower 70s to lower 80s in Long Island and southern Connecticut. A few mid 80s are possible in the immediate NYC area if there is enough sunshine.


Sunday will bring drier conditions to the area, with a low risk of an isolated shower or thunderstorm from NYC and further west. Temperatures will begin to warm up, reaching the lower to mid 80s from NYC and further west, with Long Island and southern Connecticut expected to see temperatures similar to those of today.




Next Week: Heat, Then Severe Storm Potential


The warm air mass will reach the area on Monday, bringing 850 mb temperatures as high as 18c-20c. Under sunshine and dry conditions, these 850 mb temperatures can support temperatures well into the 90s. Monday will bring partly sunny skies across the area, though as some models have been suggesting, isolated showers and thunderstorms cannot be ruled out in the evening hours from NYC and further north. With a SW/SSW wind expected, temperatures will warm up across the entire area, with temperatures in Long Island/southern Connecticut ranging from the mid 70s along the coast to the mid to potentially upper 80s closer to New York City. From NYC and further west, widespread lower 90s are expected, with mid 90s in parts of the immediate NYC area. With dew points in the mid to upper 60s, the heat index may reach the mid to upper 90s.


A back door cold front will reach the area by Tuesday, but will only barely move through before being pushed out again. An onshore SE wind is expected for Long Island and southern Connecticut, which will keep temperatures mostly in the 70s. Temperatures from NYC and further west will be slightly cooler than Monday, with mid to upper 80s expected in NYC and upper 80s to lower 90s expected west of NYC.


As the cold front approaches the area on Wednesday, temperatures will warm up once again, with more widespread lower 90s possible once again from NYC and further west. There is some slight timing uncertainty with this cold front, but there is a risk of scattered thunderstorms from Wednesday evening into the early overnight hours. The models are suggesting a risk of potentially significant severe weather on Wednesday, with the GFS showing high lapse rates as well as extreme CAPE and Lift Index values. Bulk shear, however, may be an issue, especially from the area and further south. Should these storms reach the area during the time frame mentioned above with no major changes in the modeled parameters, Wednesday evening may bring a severe weather risk to the area. Stay tuned for more information on the next update regarding Wednesday's severe weather potential.


A gradual cool down is expected by the late week, with Thursday's temperatures lowering back into the 70s to mid 80s. On Friday, the models have started to trend towards a weaker cold air mass, and I continue to expect temperatures to drop into the lower to mid 70s by Friday and Saturday. Temperatures will begin to warm up by Sunday.

Friday, May 27, 2011

May 27, 2011 Brief Update

Note: Another update may be posted tomorrow morning, otherwise the next full update will be posted on Monday, May 30.

- The 5-Day Forecast has been updated for the entire area, as well as Long Island and southern Connecticut.


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Weekend/Next Week Update:

Tomorrow will bring a risk of isolated showers and thunderstorms from NYC and further west, which should be light and widely scattered for the main part. High temperatures will range from the upper 60s to mid 70s in Long Island and southern Connecticut to the mid 70s to lower 80s from NYC and further west. Sunday will bring drier conditions with sightly warmer temperatures, reaching the lower to mid 80s from NYC and further west.

Monday is still expected to be very warm, with temperatures reaching the upper 80s to lower 90s from NYC and further west, but by Tuesday, a back door cold front previously expected to stay north of the area will move through the area, which combined with an onshore wind and the warmest 850 mb temperatures staying to the west of the area, will lower temperatures for the immediate NYC area and Long Island/southern Connecticut. Wednesday will slightly warm up ahead of the next cold front which will produce scattered thunderstorms, with severe weather also a risk.

By the late week, a colder air mass will move into the area, but some models such as the GFS may be overestimating the cold air mass, bringing high temperatures into the 60s for most of the area. At this time, I am expecting high temperatures to drop into the lower to mid 70s across the area, rising by next weekend. Stay tuned for more information on the longer range.

Thursday, May 26, 2011

May 26, 2011: 90+ Degrees Next Week

Due to technical errors, the 5-Day Forecast was completed only for the immediate NYC area as of now. The other two forecasts are in progress and will be posted on Friday afternoon.

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As the same cold front that produced deadly severe weather outbreaks over the last few days slowly moved towards the region, Pennsylvania and New York were next in line to be affected by the storms, with widespread hail and wind reports in those areas so far with the storms still ongoing. Several tornado warnings were posted as well, but at this time there are no confirmed tornadoes yet. With the area east of the storms, with dry conditions and 850 mb temperatures reaching 18c, today brought significantly warmer temperatures to parts of the area, reaching the mid to upper 80s for northern NJ and SE New York, mid 70s to lower 80s in the immediate NYC area, and in the lower to mid 70s for most of Long Island and southern Connecticut.

Weakening storms in eastern Pennsylvania are currently moving east, and are capable of producing heavy rain and gusty winds in Sussex, Warren and Orange counties before collapsing as they move towards New York City. Tomorrow will be dry once again, but temperatures will be warmer, likely reaching the 90 degree mark in parts of NE NJ and Newark. Saturday will cool down with scattered thunderstorms, but Friday's warmth is just a preview of what will come next week, with the Monday-Wednesday time frame potentially bringing the area its first heat wave of the year.


Tomorrow's Outlook:

The cold front will continue to weaken as it slowly moves east, with scattered showers and thunderstorms, some severe, expected once again in Pennsylvania and New York, but they should be less intense and less widespread than today's storms. As with today, some strong storms may reach the western parts of the area, specifically Sussex and Orange counties, with the rest of the area expected to stay dry.

With 850 mb temperatures in the 18-20c range along with partly cloudy skies and a SSW wind, tomorrow will bring the warmest temperatures so far this year to most of the area. Temperatures will reach the mid to upper 80s from NYC and further west, and a few lower 90s are possible from parts of NE NJ towards Newark and south of there. Dew points will be in the mid 60s, making tomorrow's temperatures feel slightly warmer than they will actually be. Long Island and southern Connecticut will see warmer temperatures as well, ranging from the mid 70s near the coast to the mid 80s closer to NYC.


Weekend Outlook: Slightly Colder, Some Storms

The warm air mass will slightly weaken on Saturday, with 850 mb temperatures falling into the 14-16c range. Combined with increased cloud cover and scattered thunderstorms, which may locally be strong, colder temperatures are expected, reaching the upper 70s to lower 80s from NYC and further west. Sunday will bring drier conditions with partly cloudy skies expected along with the potential for an isolated thunderstorm, with high temperatures similar to those of Saturday, potentially slightly warmer from NYC and further west.


Monday - Wednesday: Heat Wave Potential

With the cold front failing to move through the area, a very warm air mass from Texas/Mexico will spread into most of the central and eastern United States, with a large ridge in place. The nearest low pressure will be in Montana on Monday, and it will take until Wednesday for the storm's cold front to reach the area. With 850 mb temperatures rising into the 18-20c range along with partly sunny skies and a southwest wind, Monday will bring much warmer temperatures, reaching the upper 80s to lower 90s from NYC and further west, and a few mid 90s cannot be ruled out from NYC/Newark and further southwest. The latest models are suggesting a risk of scattered showers and thunderstorms on Monday evening, especially north of NYC, which if verifies, would bring a risk of strong storms to the area. At this time, I am keeping a low risk of precipitation, however this is subject to change.

With the warm air mass in place, overnight temperatures will also be mild, only dropping into the upper 60s to mid 70s in the immediate NYC area. Tuesday is likely to end up even warmer than Monday, and I am expecting temperatures to reach the lower to mid 90s from NYC and further west. Mostly sunny and dry conditions are expected.

On Wednesday, a cold front will reach the region, bringing an end to the heat. There is some slight uncertainty with timing, with the GFS showing a faster solution and the ECMWF showing a slower solution. At this time, I went closer to the DGEX's timing, with Wednesday potentially ending up even warmer than Tuesday. If the timing is slow enough, parts of the immediate NYC area could reach the mid 90s as well. With the scenario in place, severe weather may be a concern for Wednesday, with the DGEX, GFS and GGEM showing signs of severe weather. While it is too early to determine where the risk is and how big it is, the potential for severe weather on Wednesday exists. This cold front will then bring a colder air mass behind it, bringing high temperatures back into the 70s. Stay tuned for more information on this potential heat wave.

May 26, 2011 Noon: Severe Storms In PA

5:25 PM: Over the last two days, what appeared to be a minimal risk of severe thunderstorms west of the area today quickly grew into the potential for a large outbreak, with current severe weather parameters in Pennsylvania and New York State very high, with Lift Index as low as -12! With these parameters, severe thunderstorms are currently firing up to the west of the area, with some of these storms tornado warned. Some tornadoes are possible in the Northeast, with SPC placing a 10% risk of tornadoes from NE PA into central New York. Other risks from this outbreak include large hail and damaging wind gusts.

Today's action may get as far east as NW New Jersey/Orange County, NY, where locally severe storms are possible, but otherwise, the rest of the area will stay dry today and tomorrow. Temperatures up to this point reached the lower to upper 80s west of NYC, with colder temperatures east of NYC. Tomorrow will be similar to today, with another PA/NY severe weather outbreak but less intense than today's. Warmer temperatures are expected in the area as well, with parts of NE NJ and Newark likely to reach the 90 degree mark for the first time this year. Long Island and southern Connecticut will see temperatures ranging from the mid 70s near the coast to the mid 80s closer to NYC.

Stay tuned for a full update tonight discussing Saturday's scattered thunderstorm risk, next week's heat wave and a potential severe weather outbreak on Wednesday/Thursday in more details. The 5-Day Forecast page will be updated for the entire area later tonight as well.

Wednesday, May 25, 2011

May 25, 2011 Brief Update

Note: The next full update will be posted late on Thursday, May 26. This post was slightly revised early on May 26.

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Thursday - Saturday: Warmest Temperatures So Far

As a warm air mass moves into the area, with 850 mb temperatures reaching the 18-20c range, tomorrow and Friday will bring the warmest temperatures of the year so far. Thursday will still bring an onshore wind, keeping Long Island and southern Connecticut with cooler temperatures in the 70s, but from NYC and further west, high temperatures will reach the lower to mid 80s, with a few upper 80s expected in parts of the immediate NYC area. Partly cloudy skies are expected with no rain.

On Friday, the warmest temperatures will take place, when NYC and further west will reach the upper 80s, with even a few lower 90s possible from NE NJ into Newark and further south. Humid conditions are expected as well, with dew points in the mid 60s in the immediate NYC area. A severe weather outbreak will take place in Pennsylvania and New York State, and while the area will be under supportive parameters, most of the precipitation will stay to the west of the area. A few scattered showers and thunderstorms cannot be ruled out west of NYC, especially near NW NJ where some storms may be severe, but the best risk of severe thunderstorms is to the west of the area.

The weakening cold front will reach the area by Saturday, producing scattered showers and thunderstorms, potentially strong, but the severe weather risk will decrease. High temperatures will remain warm from NYC and further west, reaching the lower to mid 80s.


Next Week: Heat Wave Potential Update

Today's models continued to show signs of a heat wave for next week. An official heat wave is defined as 3 or more consecutive days of 90+ degrees, and for the NYC area, the Monday-Wednesday time frame will be close to a heat wave, if not one. Sunday will begin to slightly warm up, with temperatures reaching the lower to mid 80s away from the coast. Memorial Day will be much warmer, when 850 mb temperatures near, if not slightly over 20c are expected. Combined with mostly sunny skies and a southwest wind, this will result in high temperatures reaching the lower to mid 90s from NYC and further west.

Some models are showing a weak cold front barely dropping into the area on Tuesday before lifting north again. At this time, I do not expect temperatures to cool down by much, if at all. I am expecting warmth to continue with temperatures similar to those on Monday but slightly cooler, reaching upper 80s to lower 90s from NYC and further west. Tuesday's temperatures are still slightly uncertain and are subject to change. As a cold front approaches on Wednesday, temperatures may be slightly warmer before the front moves through, bringing a severe weather risk.

There is some slight uncertainty with the exact temperatures, but locations in the NYC area from NYC and further west are expected to see 90 or more degrees at least once in this 3-day period. Temperatures could get as hot as the mid 90s in the immediate NYC area, and while at this time, upper 90s are not expected in the area, such temperatures are likely to be found further south, towards Washington DC and Virginia. Should the warmer case scenario, with temperatures over 90 degrees each day, this may end up as the area's first heat wave of the year.

Stay tuned for more information on Thursday night regarding Friday's heat/storms and the warm spell for early next week.

Tuesday, May 24, 2011

May 24, 2011: Heat Wave Next Week?

With a cold front to the west of the area today, producing severe thunderstorms in the southern Mid Atlantic, today brought much warmer temperatures to the area, reaching the 80s in parts of the area. Temperatures tomorrow and on Thursday will be similar to those of today, but by Friday, as another storm develops to the west of the region, more warmth is expected with severe storms to the west of the area. Saturday may slightly cool down, but by Sunday or Monday, a large, very warm air mass will spread into the region, potentially bringing high temperatures in the 90s in parts of the area.


Tomorrow and Thursday:

Tomorrow and Thursday are expected to be similar, with the main difference being on Thursday when a SSE wind is expected. High temperatures will be in the lower 80s in northern NJ, upper 70s to lower 80s in NYC, and in the lower to upper 70s for Long Island and southern Connecticut. Both days will bring partly cloudy skies with dry conditions.


Friday - Saturday: Warmth, Storms Return

On Friday, a warm air mass in the Mid Atlantic will push into the area, bringing 850 mb temperatures into the 18-20c range. If the storms stay west of NYC as expected, high temperatures will be much warmer than Thursday, reaching the mid to upper 80s from NYC and further west, and parts of the area, especially from NYC/NE NJ and further south may reach the 90 degree mark.

With the storm west of the region and its cold front moving east, a significant severe weather outbreak may take place in the region. At this time, it appears that the best risk of severe weather should stay to the west of the area, potentially reaching the western parts of the area such as NW NJ and Orange County, and I drew a preliminary risk map, posted to the left, showing my current thoughts for severe weather potential risk and placement. It is possible that the risk may shift slightly east or west over the next few days.

The cold front will weaken as it moves towards the area on Saturday. Scattered showers and thunderstorms are expected, potentially strong/locally severe, with high temperatures slightly colder than those of Friday, but Friday's storms bring a higher risk of severe weather than Saturday's storms.


Sunday - Next Week: Heat Wave?

Over the last few days, I have been mentioning the potential for a significant warm spell, which now appears to be a reality. Starting on Sunday, a very warm air mass in Texas/Mexico will spread north and NE towards the central and eastern US, reaching the area as well. This will bring an area of 850 mb temperatures above 20c into parts of the region, which may last through at least Wednesday.

Similar set ups to the one expected for next week include June 2008, July 2010 and late August 2010, heat waves that each brought temperatures well into the 90s. While at this time, upper 90s are not expected in the area, given the 850 mb temperatures above 20c and the similar set ups, should the warmer case scenario verify, which I am leaning towards at this time, temperatures are expected to reach the lower to mid 90s in parts of the area, from NYC and futher west. Stay tuned for more information over the next few days.

May 24, 2011 Evening Brief Update

7 PM: Storms have failed to appear in the area up to this point, and a few isolated thunderstorms at most are expected tonight. The GFS and GGEM yesterday showed an area of strong thunderstorms moving towards the area, but this solution did not have much support from the other models, and ended up not verifying. Most of the thunderstorms today stayed in Virginia and West Virginia.

Stay tuned for tonight's update which will be posted later tonight, discussing the warmth late this week, storm potential for Saturday, and a potential heat wave next week that may bring high temperatures in parts of the area into the 90s for the first time this year.

Monday, May 23, 2011

May 23, 2011: Active Week, Weekend Ahead

On Monday, 5/23, the 5-Day Forecast page was updated for the immediate NYC area, and the Long Range Forecasts page was updated , discussing a potential significant warm spell to end the month.

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A warm air mass began moving into the region today, but the area has been under cloudy skies throughout the day, with high temperatures slightly colder than expected, reaching the mid to upper 60s from NYC and further west and the upper 50s to mid 60s in Long Island and southern Connecticut. Occasional showers and drizzle were observed throughout the day.

Tonight's storms are just the start of what will be a relatively active week and weekend. with the cold front to the west of the area tomorrow, slowly moving east, temperatures will pass the 80 degree mark in NYC for the first time this month, with the potential for strong to severe thunderstorms in the evening and overnight hours. Wednesday, Thursday and potentially Friday will be mainly dry, but warmer temperatures will return ahead of the next potential severe weather producer on Saturday.



Short Term Update: As expected, the storms mentioned in the update earlier this evening are weakening, with light to moderate rain and thunderstorms currently moving into the immediate NYC area, with a few locally heavy storms. These storms will continue to weaken as they move east into Long Island and southern Connecticut.


Tomorrow's Outlook:

With the cold front slowly moving into the region, along with warm 850 mb temperatures and a southwest wind, temperatures will reach the lower to mid 80s from NYC and further west, with the warmest temperatures focusing on the immediate NYC area. A few lower 80s are possible in parts of Long Island/southern Connecticut as well, with lower to upper 70s expected in these areas for the main part. Partly to mostly cloudy skies are expected.

With the set up in place, there is a severe weather risk tomorrow once again, but it is not as widespread as today's risk was. The afternoon hours will stay mostly dry, though by the evening and early overnight hours, the GFS and GGEM have been showing an area of strong thunderstorms targeting the area. There is some uncertainty with this feature, which the NAM model does not show, but the potential for strong to severe thunderstorm is in place for tomorrow in the late afternoon, evening and early overnight hours, especially from NYC and further north/west. At this time, I would place an enhanced 15% risk of severe weather over the area. An afternoon update may be posted tomorrow about this potential.


Wednesday - Saturday: Warming Up, More Severe Weather Possible

The storm will bring very little change in the air mass, with Wednesday still expected to be mild with high temperatures reaching the upper 70s to lower 80s from NYC and further west. An isolated shower or thunderstorm cannot be ruled out, but Wednesday will be mainly dry, with partly to mostly cloudy skies expected.

By Thursday, as another storm develops in the central US, another warm air mass will move into the region, bringing warm temperatures once again. Warmth will have some difficulty reaching the area on Thursday, with a SSE wind keeping colder temperatures towards the coast, but especially west of NYC, temperatures will be similar to those of Wednesday. As with Wednesday, a few showers and thunderstorms are possible, but most of the day will stay dry.

The warmest temperatures will finally be able to push into the area on Friday. A south wind will keep coastal areas with colder temperatures once again, but NYC and further west will see high temperatures reaching the mid 80s, and upper 80s are a possibility in Newark in the warmer case scenario. On Friday, however, with the storm closer to the area, severe weather becomes a possibility. The best risk of severe weather will stay to the west of the area, however there is the potential for scattered thunderstorms, some of them severe, in the area, especially from NYC and further west.

Saturday will bring similar temperatures compared to Friday, but the high temperatures may be slightly colder than Friday. Looking at the GFS and DGEX models, severe weather is possible once again on Saturday, with the placement of storms east of Friday, potentially bringing a better risk of severe weather into the western and central parts of the area. More information will be posted on Friday and Saturday's potential thunderstorms over the next several days.


Longer Range: The "Long Range Forecasts" section has been updated, discussing the potential for a significant warm spell starting on Memorial Day and into the rest of the week.

May 23, 2011 Evening: Storms Approaching

8:55 PM: A line of severe thunderstorms that moved through central and eastern Pennsylvania over the last few hours is currently entering the western parts of the area. These storms are still severe, with the strongest storms currently in Warren county, NJ, and northeastern Pennsylvania, moving towards Orange county, NY. The western parts of the area up to north central NJ and western Rockland county, NY will see heavy rain and thunderstorms over the next hour, with gusty winds and small hail possible as well.

(Click on the short range forecast graphic below to view it in a larger size.)

As mentioned in yesterday's update, these storms are currently entering a much more stable area, with severe weather parameters in northern New Jersey very unfavorable for thunderstorms, resulting in the storms weakening as they move east through New Jersey. Despite these unfavorable parameters, an area of supportive shear continues to move east along with the storms in Warren County, and even though the storms will begin to weaken as they move east through New Jersey and into NYC over the next 1-2 hours, the storm in Warren County may still be close to severe intensity by the time that it reaches the immediate NYC area, focusing on Morris, eastern Passaic, Bergen, Hudson and Union counties in NJ, capable of producing heavy rainfall, gusty winds, and small hail. The storm is showing signs of rotation, and an isolated tornado cannot be ruled out with this storm.


Stay tuned for a full update soon, discussing tomorrow's warmth/storms as well as another round of warm temperatures on Friday/Saturday, with severe weather possible once again on Saturday.

Sunday, May 22, 2011

May 22, 2011: Pattern Becoming More Summer-Like

Note: The 5-Day Forecast page was not updated tonight. Tomorrow night, I will update the 5-Day Forecast page, as well as the Long Range Forecasts page for more information about the potential warmth for early June. This year's Atlantic hurricane season and summer outlooks will be posted later this coming week as well.

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As a cut off low pressure left the region yesterday, nicer conditions returned into the area, with yesterday's high temperatures in the mid to upper 70s from NYC and further west, and in the mid 60s to mid 70s in Long Island and southern Connecticut. Scattered thunderstorms were observed, especially NW, north and NE of NYC, however these storms brought up to 1/4-1/2 inch at most.

As a high pressure moved down the coast from Canada, however, today brought much colder temperatures along with a southeast wind. Temperatures were colder than originally expected, only peaking in the upper 50s to lower 60s across the area. Cloudy skies and drizzle were observed throughout the day.

Today's chilly conditions will only be brief, however. A storm to the west of the region tomorrow will bring a warmer air mass, and while tomorrow will slowly warm up, Tuesday will bring the first day over 80 degrees to NYC this month, unusually late for May, along with a strong thunderstorm risk. While Wednesday will be slightly cooler, Thursday will bring warmer temperatures along with another potential of thunderstorms, and even though a slightly colder air mass will move in during the Memorial Day weekend, the potential is there for sustained warmth beyond next weekend.


Tomorrow's Outlook: Warmer, Some Storms

The high pressure east of the area today will move east, away from the region, but will still have enough of an influence to limit tomorrow's high temperatures from getting much warmer. A significant warmer air mass will move in tomorrow ahead of a low pressure in the Great Lakes, with temperatures at 850 mb reaching the 12-15c range, but with a SSE wind expected, temperatures will not warm up as much, especially east of NYC. High temperatures are expected to be in the upper 60s to lower 70s from NYC and further west except for the immediate coast of NYC, and Long Island/southern Connecticut will see highs in the upper 50s to mid 60s.

Along with the warm air mass and storm comes a severe weather risk. With NYC on the edge of the supportive parameters, the severe weather risk in the area is low, and is mostly from NYC and further west, with the best risk of severe weather existing to the west of the area. Parameters across the region are supportive enough for some severe thunderstorms, though the risk is relatively low, at 15%, focusing on Pennsylvania and western NY as well as parts of Virginia. Some severe thunderstorms may reach the western parts of the area, towards NW NJ and Orange County, NY, but will weaken as they move east towards NYC.


Tuesday - Thursday: Warm, Additional Storms

With the cold front west of the area on Tuesday, warm temperatures will finally be able to reach the area, peaking in the lower to mid 80s from NYC and further west, and a few lower 80s are possible in SW CT and western Long Island as well. With moderately supportive parameters and a risk of precipitation, there is a slight risk of strong to severe thunderstorms, especially from NYC and further west, with the storms mostly focusing on the late afternoon and evening hours.

The cold front is expected to stall near the area on Wednesday, bringing slightly colder temperatures, reaching the mid to upper 70s from NYC and further west, and the upper 60s to mid 70s for Long Island and southern Connecticut. A few showers or thunderstorms are possible, but storms are unlikely to be widespread.

By Thursday, however, as a low pressure intensifies to the west of the region, it is expected to pull in a warmer air mass ahead of another cold front. How warm it gets depends on the location and speed of the storm, as it appears that onshore winds could limit temperatures in parts of the area, but there is the potential for temperatures to once again reach the lower to mid 80s from NYC and further west in the warmer case scenario. This cold front is capable of producing more severe weather in the region, with the best risk of severe weather once again west of the area, however it is possible that there may also be some strong/severe storms in the area. Stay tuned for more information on Thursday's potential storms.


Friday and beyond:

There is some uncertainty on what happens on Friday and Memorial Weekend, but at this time, despite the risk of some showers, no washout is expected, with temperatures in the 70s and potentially lower 80s. If the storm moves slower than expected, the cold front would move through on Friday, not Thursday, bringing warm temperatures and a strong/severe thunderstorm risk as well. While this is not shown by most models at this time, it will be watched in case it becomes a trend.

There is uncertainty on the longer range as usual, but beyond the Memorial Weekend, the long range models are suggesting the possibility of a significant warm spell affecting the central and eastern United States, including the area. This is still too far in the long range to know for sure, and it is possible that there is no significant warm up, but the potential is there for the first major warm spell of the year in the NYC area. More information will be posted as details become clearer.

Friday, May 20, 2011

May 21, 2011 Morning: Update On Next Week

Note: As there are significant changes taking place with the forecast, this discussion was updated on Saturday morning to discuss these changes in more details. The 5-Day Forecast will be updated this afternoon to reflect the changes as well.

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The upper level low that has been stuck over the region for almost a week, bringing widespread rain and thunderstorms, moved over the area yesterday as it slowly started to leave the region. Originally, it appeared that yesterday would bring a strong thunderstorm risk, but with the upper level low right above the area, other than a few showers most of the area stayed dry, with strong to severe thunderstorms to the north, south and west of the area, rotating counterclockwise around the low.

With the upper level low finally exiting the region, much nicer conditions will return for this weekend, other than the risk of isolated thunderstorms this afternoon, especially northeast of NYC, with partly sunny skies and high temperatures in the 60s and 70s. These conditions will be brief, however, as an approaching cold front and warm air mass for next week bring warmer temperatures as well as the risk for thunderstorms in parts of the week.


Weekend Outlook:

With the upper level low moving out of the region, today will bring clearing skies to the area, with partly sunny skies expected. The low will still be capable of producing isolated showers and thunderstorms this afternoon, especially north and NE of NYC towards SE New York, Long Island and southern Connecticut, and while a few of these storms may become strong, these storms are likely to stay below severe levels and will not be as widespread or as strong as the storms today and yesterday in the region.

Warmer temperatures are expected today as well, reaching the lower 60s to lower 70s for Long Island and southern Connecticut, and the mid to upper 70s from NYC and further west. While not modeled at this time, parts of NJ may reach the 80 degree mark, but this should stay to the south/SW of NYC.

Sunday will bring colder temperatures as a high pressure moves south off the coast, bringing an onshore wind into the area. Places west of NYC should not be affected as much, with highs in the upper 60s to mid 70s, with mid 60s expected in NYC, but Long Island and southern Connecticut will see much colder temperatures, expected to only reach the lower 50s to lower 60s.


Next Week: Warmer Temperatures Return, Some Storms

Over the last day, significant changes have been taking place with the expected scenario, and it no longer appears that there is a major warm up or a significant severe weather outbreak headed towards the region on Tuesday.

Originally, a low pressure was expected to move slowly through southern Canada on Monday/Tuesday, slowly bringing in a warm air mass on Monday with partly sunny skies and highs in the mid 70s to lower 80s from NYC and further west and bringing severe weather on Tuesday as the cold front approaches the area. This scenario is no longer favored, however, as a cold air mass in Canada is expected to push towards the area more than originally modeled, and with the storm moving faster, Monday will be the day that brings widespread thunderstorms, some strong, to the region, with the cold front already moving through the area by Tuesday afternoon.


Monday: With a high pressure still offshore on Monday, an onshore wind is expected for places east of NYC, including NYC, with the warm front likely to be placed near NYC during the afternoon. As a result, high temperatures are likely to be in the upper 60s to mid 70s for NYC, lower to upper 70s west of NYC, and the mid 50s to mid 60s east of NYC. There is still some slight uncertainty, and these temperatures are subject to slight changes. As the cold front approaches the region from the west, widespread showers and thunderstorms are expected, especially in the afternoon and evening hours. With supportive parameters, some of these storms will be strong or severe, especially towards Pennsylvania, western NY, and the rest of the central/southern Mid Atlantic. As NYC should be near the edge of the warm sector, thunderstorms are expected from NYC and further west, potentially strong, but the best risk of severe weather exists to the west of the area.

Tuesday: The cold front is expected to move through on Tuesday, bringing mainly dry conditions, though scattered showers and thunderstorms, potentially strong, are still possible. With a west/WSW wind expected along with partly cloudy skies, warmer temperatures will return, reaching the lower to mid 80s across most of the area, even including Long Island and southern Connecticut away from the coast. The warmest temperatures will be in the immediate NYC area, where mid 80s are expected. With the front nearby, however, temperatures are unlikely to get much warmer than the mid 80s, and this will also prevent the originally expected severe weather outbreak from taking place, instead bringing a risk of scattered showers and thunderstorms.

Late Week: The cold front from Tuesday is expected to stall on Wednesday and potentially Thursday near the area. Should this scenario take place, it would bring drier conditions for Wednesday along with colder temperatures, reaching the 70s in NYC and further west. The 06z GFS shows a severe weather outbreak on Wednesday, however at this time this scenario is an outlier. By Thursday and Friday, a storm to the west of the region, potentially a cut off low, may bring a warmer air mass into the area again as well as a severe weather risk, but as this is in the longer range, details may change. Stay tuned for more information on next week and the Memorial Day weekend with tonight's update.

Thursday, May 19, 2011

May 19, 2011: Severe Weather Next Week?

Note: The 5-Day Forecast page was updated for the immediate NYC area only tonight. Each night, the list of pages that have been updated will be listed in the top right corner of the website, above the radar loop.

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After several days of widespread heavy rain affecting the area, bringing rain totals from 1.5 to as much as 5-7 inches of rain across the area, today was an improvement over the last several days, with partly to mostly cloudy skies across the area and high temperatures reaching the lower to mid 70s across most of the area. The only significant rainfall today came from severe thunderstorms in far western New Jersey, mostly limited to Warren County, and strong thunderstorms that popped up in Rockland county in NY late this afternoon.

Tomorrow will bring slightly more widespread storms as the upper level low moves near the area, and even though these storms will not be as widespread as the storms over the last several days, they will still be capable of producing locally heavy rainfall. The weekend will bring much nicer temperatures with dry conditions, but a warm air mass pushing into the region will bring activity back into the region for next week, first the warmth and then the potential for a severe weather outbreak.


Tomorrow's Outlook:

With the upper level low moving over the area, tomorrow will start out with mainly cloudy skies and fog across the area. The fog will clear by the late morning for most of the area along with clearing cloud cover, with partly to mostly cloudy skies expected by noon. During the late afternoon, widespread showers and thunderstorms will form across the area, and while a severe weather outbreak is not expected as a result of this, some storms could be strong, producing locally heavy rainfall. The storms will persist through tomorrow evening and the early overnight hours before weakening.

High temperatures tomorrow will be slightly colder than today's temperatures, reaching the upper 60s to lower 70s across the area. With the upper level low over the area, a light variable wind is expected.


Weekend Outlook: Comfortable, Dry

This coming weekend will finally bring a break in the rainfall, making this the first time there is no rain in the area since last Saturday. High temperatures will be in the mid to upper 70s from NYC and further west, with Long Island and southern Connecticut seeing colder temperatures, ranging from the lower 60s near the coast to lower 70s closer to NYC.

As a high pressure off the coast moves south, a southeast wind will bring colder temperatures, especially for places east of NYC. There is slight uncertainty with high temperatures, though at this time I am expecting high temperatures in the mid 50s to mid 60s east of NYC, and in the upper 60s to mid 70s from NYC and further west. These temperatures are subject to slight changes, and it is possible they may have to be raised slightly.


Next Week: Warmth Returns, But Storms Return As Well

As previously mentioned, a much warmer air mass will move into the region next week, bringing the return of warm temperatures and the first time NYC passes the 80 degree mark this month. Monday is expected to bring temperatures in the mid 70s to lower 80s from NYC and further west, and the mid 60s to mid 70s east of NYC. Partly to mostly cloudy skies are expected, with scattered showers and thunderstorms possible from NYC and further west in the late afternoon and evening hours.

The warmest temperatures are likely to be on Tuesday and potentially Wednesday. The low pressure is expected to be well to the north of the area, and with 850 mb temperatures over 15c, high temperatures will be in the lower to mid 80s from NYC and further west as well as parts of Long Island/southern CT away from the coast. Upper 80s are a possibility in Newark, NJ as well. Meanwhile, all models show a cold front approaching the region on Tuesday, and with some models such as the GFS showing high lift index and CAPE values as well as supportive lapse rates, storms on Tuesday afternoon and evening have the potential to be strong or severe.

Beyond Tuesday, there is some more uncertainty. The 12z ECMWF brings colder temperatures back with a high pressure nearby on Wednesday, while the GFS and DGEX bring the cold front closer to the area on Wednesday while keeping warm temperatures in place, even slightly warmer than those of Tuesday. Such a scenario would bring a higher risk of severe weather on Wednesday, with temperatures above average but not as warm lasting through Thursday and Friday. There is uncertainty with which scenario verifies, but the risk of thunderstorms, potentially strong or severe, may continue through Wednesday and Thursday. Stay tuned for more information on the longer range.

May 19, 2011 Noon: Storms In Western NJ

3:40 PM: There is currently an area of strong thunderstorms in eastern Pennsylvania, and with favorable severe weather parameters, strong thunderstorms are currently forming in western NJ, with a strong thunderstorm in Warren county, and moving NNW. With supportive parameters in place, northwestern NJ and Orange County will be affected by thunderstorms through the rest of this afternoon and evening, which will be capable of producing heavy rain due to their slow motion, small hail, and gusty winds. Northeastern NJ and Rockland County in NY may see a few storms, but the majority of the action will stay further west. Places east of NYC will not be affected by today's storms.

Wednesday, May 18, 2011

May 18, 2011: Warm, Stormy Next Week

Due to the storm updates, the other pages were not updated tonight. The 5-Day Forecast page will be updated with tomorrow's update.

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Short Term Outlook:


10 PM: Over the last hour, showers and thunderstorms began developing over the immediate NYC area and moving northwest, producing additional moderate to heavy rain showers. As this area of rain expands and bring a slightly longer duration moderate/heavy rainfall to Sussex county, more showers are developing southeast of NYC and moving towards the coast while intensifying, resulting in showers and thunderstorms persisting over the next several hours from NYC and further west.

East of NYC, heavy storms in Connecticut are currently weakening, with areas of light rain affecting Long Island and southern Connecticut. There is another area of heavy rain and thunderstorms offshore moving towards central/eastern Long Island and south central/SE Connecticut, though these storms appear to be slightly weakening at this time.


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The area has been stuck under mainly cloudy skies and occasional showers and thunderstorms since Sunday, though yesterday and today brought the most significant rainfall amounts as the cut off low stalled near North Carolina/Virginia, drawing in a lot of moisture into the region. Yesterday failed to produce much rain due to subsidence, though since last night, rain has been able to move into the area without completely dissipating just off the coast.

The heaviest rains are mostly over, though rain will continue through tonight and tomorrow, with scattered thunderstorms lasting through Friday and Saturday. Beyond Saturday, however, a warmer pattern will develop, with parts of the area reaching the lower to mid 80s early next week, the first time this has happened this month, along with a severe weather risk on Tuesday and/or Wednesday.


Late Week: Rain Continues

Thursday and Friday will finally bring warmer temperatures, reaching the upper 60s to mid 70s from NYC and further west, similar to where they were last week, but the rain and thunderstorm risk continues. The early afternoon hours of Thursday should be dry, and some clearing in the cloud cover is expected, but with the upper level low near the area along with decent Lift Index (LI), CAPE, and Lapse Rates, widespread showers and thunderstorms will develop in the late afternoon, with the best risk of storms from NYC and further west. Some storms could be strong or potentially severe, but a widespread severe weather outbreak is not going to take place.

Friday will bring similar conditions, but with slightly warmer temperatures, more clearing in the cloud cover, and another strong thunderstorm risk from NYC and further west in the late afternoon and evening hours.


Nice Weekend, Warm And Stormy Next Week

Other than a risk of isolated showers and thunderstorms on Saturday afternoon and evening, temperatures will continue to warm up, reaching the lower to upper 70s from NYC and further west. By Sunday, however, as a high pressure is expected to be just east of the area, an onshore wind will develop, bringing high temperatures back into the 60s. Monday will be slightly warmer, with lower 70s possible west of NYC.

By Tuesday, a summer like air mass is expected to move into the region, with 850 mb temperatures ranging from 15-20c, which in a typical summer day can bring 90 degrees. High temperatures are slightly uncertain, but at this time, I am expecting lower to mid 80s from NYC and further west for Tuesday and Wednesday, and even upper 80s cannot be ruled out in Newark, NJ in the warmer case scenario. Lower temperatures are expected east of NYC, though a few lower 80s are expected in these areas away from the immediate coast as well.

A cold front is expected to approach the area sometime around the middle of next week. The exact timing is uncertain as well as the smaller details, but when looking at the overall picture, all models are in agreement by showing widespread precipitation across the region, especially in the afternoon and evening hours. With the area expected to be in the warm sector of the storm, thunderstorms are likely with the cold front, and the GFS is consistently showing supportive Lift Index and CAPE values. As should be expected with something at least a week away, nothing is final yet and details may change, though there is a risk of strong to severe thunderstorms affecting the region, including the NYC area, around the middle of next week. More information will be posted as details become clearer.

May 18, 2011 Storm Updates

Below, storm updates will be posted on the heavy rain and thunderstorm event that is currently affecting the area. Scattered showers and thunderstorms, some of them strong, are expected on Thursday and Friday, though separate storm updates will be posted for these storms.


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6:10 PM: Storms In Long Island

The band of rain has cleared places west of NYC for the main part, though heavy storms continue to affect places north and east of NYC. The strong storms previously mentioned as heading towards central Long Island have not weakened, and are producing very heavy rain and thunderstorms in western/central Suffolk county. These storms are also extending into parts of southwestern Connecticut and northern Westchester county, NY.

Storms will begin to weaken in Long Island within the next 1/2 hour as the main band moves away, with the bands in SW Connecticut shifting north, moving through and just north of Bridgeport. Rain is expected to intensify in parts of Orange County, NY as the area of storms moves into that area.

Behind this area of rain, however, the new storms approaching the area are significantly weakening, and the convection offshore is also weakening. Additional rain is expected this evening and tonight, but the current band of rain is likely the heaviest the area will see through tonight.


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3:40 PM: Heavy Rain Returns

Since this morning's post, mostly dry conditions were observed with rain falling to the SW and NE of the area. Some scattered showers were observed in the area, though most places saw clearing in the cloud cover, with mostly to partly cloudy skies observed around noon. As mentioned this morning, today was expected to stay quiet until the mid afternoon, when convection offshore would move into the region and produce more rain. The area of rain has reached the area, and is now starting to produce widespread moderate to heavy rain that will continue through the late afternoon and evening hours.

Looking at the latest radar, a long band of moderate to heavy rain and thunderstorms is stretching NW, from the waters southeast of NYC through NYC itself and all of northern New Jersey. Northeast of the band, scattered thunderstorms are quickly forming across southwestern Connecticut. This band will continue to shift towards the NW/NNW, spreading heavy rain into southeastern New York, western Long Island, and southwestern Connecticut, with rates generally between 1/2 and 1 inch of rain per hour. There are strong thunderstorms in the eastern part of this band moving towards central Long Island, more specifically near western Suffolk county, and while these strong storms may weaken in intensity when they reach the coast, they will still be capable of producing moderate to heavy rain.

This band is not the last one that will produce rain today. The latest water vapor loop shows that there is plenty of storm activity offshore that will move north, then northwest towards the NYC tri-state area. Some of this activity may very well weaken before reaching the coast, but it is still expected to produce additional rain in the area. The bands later tonight may target places further east than the current band over the area, and some breaks are expected in between the bands, but the next few rounds of rain will help add to the already high rain totals across the area, with radar estimates showing that almost the entire areas has seen over 1.5 inch of rain up to this point since Sunday.


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Wednesday, 5/18
9:20 AM: More Rain Likely Later Tonight, Preview Of Next Week

While the area of storms that approached northern NJ last night weakened as it reached the area, more storms affected the area overnight, focusing especially from NYC and further east. The most recent rainfall to affect places west of NYC was from a heavy rain shower earlier this morning that moved through NW NJ/Orange County while intensifying. The radar as of now is not very impressive, with only widespread showers across the region with some of those showers weakening/dissipating. The short range models also do not show much, if any significant rainfall during the day, with more rainfall during the night.

Looking at the current observations, most of the rain is expected to stay to the SW and NE of NYC, especially with an area of heavy thunderstorms currently southeast of Delaware headed towards southern New Jersey, Delaware and SE Pennsylvania. Some clearing in the cloud cover is even possible in the short term in the immediate NYC area before more clouds return later on, with occasional breaks in the cloud cover also possible later on today.

Some showers and storms are expected through the early afternoon, with an area of storms off the coast of North Carolina potentially affecting parts of the area early this afternoon should it reach the region without collapsing or changing direction, but the better risk of more widespread heavy rain in the area is likely to wait until at least the mid afternoon at the earliest when convection offshore should approach the region, with the evening and overnight hours more likely to bring widespread rain into the area. Stay tuned for more updates on this later this afternoon.

Longer Range: The main long range models continue to show summer-like 850 mb temperatures for next week, getting as high as 18 to 20 degrees celsius, which in a typical summer day can bring 90 degrees. The GFS is colder with surface temperatures, showing lower 80s in NYC on Tuesday, with the DGEX showing warmer temperatures getting as high as the upper 80s near NYC. The exact temperatures are uncertain at this time, though it appears that there may be an onshore wind on Sunday/Monday, limiting temperatures, with Tuesday and Wednesday likely to bring temperatures into the lower to mid 80s in NYC. There is also the risk of severe weather with the warm up, which will be discussed in a full update tonight.

Tuesday, May 17, 2011

May 17, 2011 Storm Updates

Below, storm updates will be posted on the heavy rain and thunderstorm event that is currently affecting the area. Scattered showers and thunderstorms, some of them strong, are expected on Thursday and Friday, though separate storm updates will be posted for these storms.


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9:40 PM: Rain Finally Returns

Since the last update was posted, rain continued to dissipate just off the coast, and eventually the rain off the coast of Long Island/NJ mostly dissipated as well, with only a few showers and thunderstorms remaining. Parts of the area, especially west and south of NYC, saw some continued to see some clearing in the cloud cover. Over the last 1/2 hour, however, rain has been finally able to move into the coast, and is now headed towards the immediate NYC area.

The area of rain and thunderstorms seen in the previous radar southeast of Delaware has moved up the coast while maintaining its intensity, and as it moved into New Jersey, it began to intensify, the first time rain has intensified over New Jersey since this morning. The area of storms is currently just east of central NJ and is moving NNW. There is some slight uncertainty regarding whether it reaches the NYC area at its full intensity or if it weakens before reaching the area, but should it maintain its intensity, a round of heavy rain and thunderstorms will affect northern NJ, SE New York and NYC starting around at least 10:30 PM or 11:00 PM.

Meanwhile, there is also an area of rain and thunderstorms affecting parts of Long Island and southern Connecticut. This area of rain is currently weakening in southern Connecticut, however it is an improvement over this afternoon when the rain could not even reach the coast without completely dissipating. These areas will continue to see scattered showers and thunderstorms.


Tonight And Tomorrow: The two rounds of rain affecting the area will be followed by more. The water vapor loop shows additional storms developing well off the coast of North Carolina, and the regional radar also shows storms off the coast moving towards the area. These storms are still having some trouble moving towards the area, and some are still weakening, though additional rain and thunderstorms are expected across the area tonight, locally heavy, with a general 1/4 to 1 inch of rain across the area with locally higher amounts.

There is some uncertainty for tomorrow, as some models show a scenario like that of today while others bring more heavy rain. I will discuss this more in an update tomorrow morning, though at this time, I am expecting tomorrow to bring occasional rain and thunderstorms as well, with parts of the day dry and other parts of the day wet. These occasional storms will continue through Wednesday night.


Brief Longer Range Update: Thursday, Friday and Saturday will each bring similar conditions, with fog potential early on, skies clearing to become partly to mostly cloudy, followed by increasing clouds and widespread showers and thunderstorms developing by the late afternoon and evening hours. Some of these storms have the potential to be strong or potentially severe, but the potential for severe thunderstorms is not a big one. By Sunday, a much warmer air mass will return, and temperatures will rise into the 80s across parts of, if not most of the area. There is the potential for temperatures to reach the mid 80s sometime early next week ahead of the next rain maker, which will produce showers and thunderstorms with the exact timing uncertain. More information on the longer range will be posted over the next few days.


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5:30 PM: Rain Unexpectedly Dissipating Offshore

When posting the last update late this morning, there was a solid area of moderate to heavy thunderstorms headed towards the area. It appeared that it would reach the area and bring additional heavy rainfall, but before it was able to do so, most of the rainfall headed towards New Jersey/NYC dissipated while additional moderate to heavy rain and thunderstorms continued to affect Long Island and southwestern Connecticut.

Since then, most of the afternoon has been the same, with rain and thunderstorms constantly dissipating just off the coast of NJ while Long Island and southern Connecticut continued to see storms, but the storms affecting Long Island are beginning to weaken as well. Today was not expected to be a constant washout, but all of the rain was not expected to simply dissipate offshore. In addition, parts of New Jersey are even seeing breaks in the cloud cover when rain was supposed to fall.

Most models did show rain for today, but the 00z and 06z NAM did correctly show most of the rain this afternoon staying in Long Island with little to no rainfall from NYC and further west. These runs bring in heavy rain tonight, with a similar scenario tomorrow bringing dry conditions once again. The short range NMM/ARW models also did not show much rain today while bringing heavy rainfall tonight and tomorrow. The other short range models, such as the RUC, show heavy rain later tonight, but they continue to repeat the same mistake by bringing the offshore rainfall inland within the first 2-3 hours of the run.

With the rain still dissipating off the coast of New Jersey, it is difficult to determine when rain will return into most of the area again and how strong it will be, but with the latest observations, dry conditions are expected to continue through the evening hours, possibly lasting even beyond the evening. Depending on what happens over the next several hours, I may have to lower forecast rainfall amounts across parts of the area. More information will be posted on this later tonight.


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10:50 AM: Another Round Of Heavy Rain

The storms that affected the immediate NYC area early this morning are currently focusing on areas north/east of NYC, with heavy thunderstorms currently affecting central Long Island and SW Connecticut. These storms are moving northwest, and will begin to end within the next 1/2 hour. Meanwhile, scattered thunderstorms have been affecting NYC and northern NJ, bringing locally heavy downpours.

The latest radar is indicating a large area of heavy rain and thunderstorms well southeast of NYC, moving NW as well. The tilt of the storm is moving the areas of rain towards the NW while shifting slightly north at the same time, as we've seen with this morning's storms, and this area of rain is expected to affect New York City, western/central Long Island, SW CT, far northeast NJ, and SE New York within the next 1-2 hours. NYC is expected to be in the SW edge of this area of rain, and places just southwest of NYC may not see much impact from this area of rain.

The next update will be posted this afternoon.


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9:15 AM: Heavy Rain Just Starting

Early this morning, a band of heavy rain and thunderstorms set up over the immediate NYC area, extending from western Long Island/NYC/NE NJ into southeastern New York, where 1/2 to just over 1 inch of rain fell just this morning. This brings the estimated storm totals through this point to 1/4 to 1 inch in Long Island/S CT, and 1 to 3 inches in NYC, northern NJ and southeastern NY. Radar estimates show that as much as 4 inches of rain have fell so far in NW NJ, specifically in Sussex and Somerset counties.

The band of heavy thunderstorms is still mostly offshore, steadily moving NW, but is drifting north, currently affecting eastern Nassau county and central Westchester county. There is an area of moderate to heavy rain southwest of the main band, which will affect western Long Island and extreme northern New Jersey with additional rain over the next 1-2 hours.

A break in the rain is expected for the central and western parts of the area late this morning into parts of the early afternoon, but this is only the start of the heavy rain and thunderstorms, which will last through Wednesday night. More rain and thunderstorms will move into the area later today, bringing more localized downpours, with the heaviest storms likely to be tonight into tomorrow. Stay tuned for more storm updates later today, as well as another update this evening briefly discussing the time frame beyond this storm, including scattered strong thunderstorms for Thursday/Friday and a significant warm up next week that will bring NYC's temperatures above the 80 degree mark for the first time this month.

Monday, May 16, 2011

May 16, 2011: Storm Brings 4+ Inches Of Rain

Note: The 5-Day Forecast page was updated tonight. An update will be posted tomorrow morning as well.

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As rain and thunderstorms fell to the north and south of the area today, staying nearly stationary, today brought mainly cloudy skies to the area. Temperatures ended up significantly busting, however, as the NAM, which was the coldest model compared to the others, ended up being correct with high temperatures in the 50s during the middle of the day across the area. Conditions were mainly dry today other than some scattered showers, though locally heavy thunderstorms affected western NJ and Orange County, NY, bringing the total rainfall from the storm so far to an average of 1.5 to 3 inches of rain in these areas.

The worst has yet to come, however, as tomorrow and Wednesday will bring more widespread heavy rainfall. Thursday will be drier, though occasional showers and storms will persist through the weekend, which will be followed by much warmer temperatures, likely bringing NYC's temperatures into the upper 70s and 80s for the first time this month next week.


Tomorrow And Wednesday: 2-4+ Inches Of Rain Expected

As mentioned over the last several days, with the low pressure expected to stall near North Carolina and southern Virginia, it will pull in a lot of Atlantic moisture into the region, producing heavy rainfall from Washington DC to Connecticut, with the heaviest rain modeled to affect the NYC area.

The exact rain amounts, however, are tricky to determine with this storm. Unlike typical fall and winter rain storms, where the heaviest amounts usually cover a widespread area, the highest amounts with this storm will be in isolated locations as the storm produces widespread areas of rain and thunderstorms, capable of producing heavy downpours. A general 2 to 4 inches of rain are expected across the area over the next 2 days, though some areas will see less rain than expected while others see more than expected, especially west of NYC, where rain amounts may locally get as high as 5-6 inches.

With the given scenario, the exact timing of the rain cannot be nailed down, however rain is expected to spread into the area late tonight, with occasional moderate to heavy rain lasting through tomorrow and Wednesday. The heaviest rainfall is shown to be on Tuesday night at this time, with some models showing another round of heavy rain and thunderstorms on Wednesday night. The cloud cover, rain and onshone wind will help keep chilly temperatures in place, with tomorrow's high temperatures expected to be in the mid 50s to lower 60s and slightly warmer temperatures on Wednesday.


Thursday And Beyond: Warmth Returns, Rain Continues Early On

As the cut off low begins to exit the region, Thursday and Friday are expected to bring scattered showers and thunderstorms to the region. Some of these storms will be capable of producing locally heavy rainfall, but rain won't be anywhere near as heavy as it will be tomorrow and on Wednesday. Temperatures will warm up as well, reaching the upper 60s to lower 70s from NYC and further west. With drying conditions next weekend, temperatures will continue to warm up, and next week, ahead of the next potential rain maker, temperatures are likely to reach the upper 70s and potentially the 80s, making this the first time NYC has reached the 80 degree mark this month.

Sunday, May 15, 2011

May 15, 2011: Heavy Rain Tuesday, Wednesday

As a large, slow moving storm began moving into the region today, widespread rain fell in the Northeast, with moderate to locally heavy showers and thunderstorms affecting the area, especially from NYC and further west. Storms are still ongoing in the western parts of the area, especially in Warren, Sussex and Orange counties, adn while places further east are expected to see some storms tonight, by the time that the storms reach NYC, if they do so at all, they will be much weaker. Radar estimates show that rain totals as of now are up to 1/4", locally 1/2" in Long Island/southern Connecticut, and between 1/2 and 1 inch, locally up to 2-3", from NYC and further west.

Today's storms are just a preview of what this week will bring. The cut off low will drift south and stay nearly stationary through most of this week, drawing in Atlantic moisture and producing widespread moderate to heavy rain and thunderstorms, especially on Tuesday and Wednesday. Even though the storm will weaken by Thursday and Friday, scattered showers and thunderstorms will persist through the end of the week and into next weekend as well.


Tomorrow's Outlook:

Tomorrow will be the warmest day of the week for most of the area, as the low pressure is still to the west of the area, slowly drifting south, placing the area in the northern edge of the warm sector of the storm. With an east wind expected, high temperatures will rise into the upper 60s to lower 70s from NYC and further west, and the lower to mid 60s for the eastern parts of the area, potentially in the upper 50s in the immediate coast. The NAM is the cold outlier at this time, only showing highs in the lower to mid 50s across the area, and I sided with the warmer GFS/GGEM for tomorrow's temperatures.

Mainly cloudy skies are expected, though some breaks in the cloud cover are possible in the afternoon. In the afternoon and evening, scattered showers and thunderstorms are expected again, capable of producing locally heavy rainfall, but the storms are unlikely to be as strong/heavy as today's storms were.


Tuesday-Wednesday: Heavy Rain, Thunderstorms

As previously mentioned in yesterday's update, as the low pressure drifts south into North Carolina, it will pull in moisture from the Atlantic Ocean, resulting in a heavy rain potential for parts of the region. This will not be a solid area of widespread, consistent moderate to heavy rain, but rather widespread areas of moderate to heavy rain and thunderstorms capable of producing downpours. Steadier rain will move into the area early on Tuesday morning, and will continue through Tuesday, Wednesday and parts of Wednesday night.

During these two days, at least 1.5 to 3 inches of rain are expected, though amounts may be locally as high as 4-5 inches of rain. By the time that the main part of the storm ends on Thursday, rain totals including today will end up between 2-4 inches, with isolated locations potentially seeing as much as 6 or more inches of rain.

Behind this storm, scattered showers and thunderstorms will continue, but temperatures will get warmer. Tomorrow's update will discuss this in more details.