Friday, September 30, 2011

Sept 30, 2011: Latest Pattern Outlook

This discussion, posted on Saturday morning, covers the outlook for this weekend, next week and next weekend. The other pages were not updated today, and will be updated on Saturday evening.
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Today's Outlook:

The outlook for today remains the same from last night's update. Partly sunny skies with a SSW wind are expected, with high temperatures reaching the lower to mid 70s inland, mid to upper 70s in the immediate NYC area, and the mid 70s across most of Long Island and southern Connecticut.


Weekend Storm Outlook: Rain Returns

The outlook for this weekend has turned much more complicated over the last several days than first thought, as an upper level low will sit over the region for this weekend through early next week, extending the already ongoing period of mostly cloudy and unsettled conditions into the first week of October. The models have had issues with the handling of this cut off low pressure, mostly showing it staying to the north/east of the region, either offshore or over Canada, but trends over the last 24-36 hours have placed this low much further south/west than first thought, over the NYC area into Pennsylvania.

As the upper level low moves into the area tonight, a wave of low pressure will form east of the Mid Atlantic tonight, bringing rain up the coast from SE Virginia into New Jersey and Connecticut. Light to moderate rain will develop across the area after 12 AM and will continue through Saturday morning, with 1/4 to 1/2 inch of rain expected to fall across  the area tonight. As the low pressure tilts towards the NW while moving over NYC on Saturday, the heavier bands of rain will push further northwest, affecting New York and Pennsylvania, while the NYC area sees occasional showers. These scattered showers will continue through Sunday before becoming more isolated by Sunday night. Between Saturday and Sunday night, an additional 1/4 to 1/2 inch of rain is expected to fall across the area, bringing the storm total to 1/2 to 1 inch across the area.

As the storm will trap the cold air mass over the Mid Atlantic, sub-freezing 850 mb temperatures are expected in that region, which combined with precipitation, will produce light to moderate snow over the higher elevations of West Virginia. The potential is even there for light accumulations should the snow fall heavily enough.


Weekend Temperature Outlook: Cooling Down, But No Major Cold

Due to the cut-off low pressure, the previously expected strong cold spell has been eliminated as well. With the cut-off low moving into NE Pennsylvania and southern New York, the cold air mass will be trapped over the Mid Atlantic, where chilly high temperatures in the 50s to lower 60s are expected along with a chilly NW/WNW wind. With the storm to the west of the area, however, a south wind is expected, with SE winds over New England pulling in a mild air mass from offshore, with high temperatures reaching the 60s to lower 70s in parts of New England.

With the NYC area expected to be in between the warm and cold air masses, temperatures will be chilly in the area, but will not be as cold as mentioned over the last few days. On Saturday, high temperatures are expected to peak in the lower to mid 60s inland and in the mid to upper 60s across the rest of the area. On Saturday night, low temperatures will drop into the mid to upper 40s west of NYC, and in the lower to mid 50s from NYC and further east. With cloudy skies and scattered showers on Sunday, high temperatures will reach the mid to upper 50s in NW NJ/SE NY, lower 60s in the immediate NYC area, and the mid 60s east of NYC, in Long Island and southern Connecticut. A south, potentially SSE or SSW wind is expected for Sunday. Sunday night will bring chilly temperatures as well, dropping into the lower to mid 40s inland, mid 40s to lower 50s in the immediate NYC area, and the lower to mid 50s in Long Island/S CT.

The reason why temperatures will not be as cold as first expected is not due to a weaker cold spell than expected. The expected intensity of the cold when entering the Ohio Valley has not changed from what it was several days ago. What has changed was the scenario, with the cut-off low, previously expected to stay  east of New England, now expected to stay west of NYC. If the previously expected scenario where the cut off low stays east of the region or even over New England had verified, then the expectation for high temperatures reaching the lower to upper 50s across the area with lows in the upper 30s to mid 40s would likely have verified; even the models showing that scenario were much colder, showing highs in the 40s west of NYC. With the cut-off low now expected to end up to our west, however, the NW wind was replaced with a S/SW wind bringing in warmer temperatures, and even though the models are trending warmer, most of them are still going colder, showing highs in the 50s across most of the area, which based on the latest expectation, may be too cold.


Next Week's Outlook: Staying Chilly, Then Warming Up


When the cut off low was expected to stay to the east of the region, the expectation was there for the cold spell to exit with a much warmer air mass moving in by early next week. Due to the new expectation for the cut-off low, however, the warm air mass will fail to quickly build into the region, and with the upper level low merging back into the main flow, another strong trough will dig into the region, but this time, due to the upper level low moving further east, the trough will only affect New England with the colder temperatures for Tuesday into Thursday, with the NYC area in the edge of this trough.

The cut off low will remain stationary over the region for Monday, with high temperatures expected to reach the upper 50s to mid 60s across the area. By Tuesday, a strong high pressure will move in from Canada, which will bring mostly sunny skies along with dry conditions. This high pressure will stick around through the weekend, keeping mostly sunny skies and dry conditions in place, making this the first prolonged period of dry conditions since the middle of September. The temperatures, however, will vary, ranging from a chilly mid week to a warm weekend.

High temperatures on Tuesday are expected to reach the mid to upper 60s across most of the area, with lower to mid 60s inland. Colder overnight lows are expected for Tuesday night, dropping into the lower to upper 40s away from NYC. High temperatures will stay in the lower to upper 60s across the area on Wednesday, and will slightly warm up by the late week, reaching the upper 60s to lower 70s by Friday. The warm air mass is not expected to reach the region at its peak intensity, with the warmest temperatures staying to the west of the region, but regardless, temperatures will warm up next weekend, reaching the 70s across the area. Stay tuned for more information on next week and next weekend's outlook.



Thursday, September 29, 2011

Sept 29, 2011: Cold Weekend, Chilly Week Ahead

NOTE: Tonight's discussion was split into two parts. The first part of the forecast, discussing the outlook through this weekend, was posted tonight. A more detailed update on Saturday morning will discuss the weekend in more detail, as well as the outlook for next week into next weekend.

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With the cut-off low that affected the region over the last week finally merging with another storm in Canada, a cold front moved through the area today, bringing widespread thunderstorms, some of them strong to severe, producing small hail and gusty winds. Over the last 2-3 days, rain totals ended up between 2-5 inches in NW NJ/SE NY, 1/2 to 1.5 inch in the immediate NYC area, and 1/4 to 1 inch across Long Island and southern Connecticut, according to the latest radar estimates.

As a second but dry cold front moves through the area tomorrow, warmer temperatures will return, with temperatures nearing 80 degrees in parts of the immediate NYC area. Behind this front, a significantly colder air mass will move in, keeping high temperatures below the 60 degree mark for Sunday while bringing the potential for light snow in the higher elevations of West Virginia, Pennsylvania and New York. Another Canadian trough moving into the Northeast next week will keep chilly temperatures in place through the middle of next week, but by next weekend, a large ridge from the central US will spread in, and may bring much warmer temperatures by next weekend.


Tomorrow's Outlook:


Even though a cold front moved through the area today, another front to our west will be the one that will push the warmth out. This front will move through the area on Friday night, which will bring warmer temperatures into the area for Friday. With 850 mb temperatures near 11-12 degrees celsius along with partly sunny skies and a SW/SSW wind, temperatures tomorrow will be warmer, reaching the mid 70s inland, upper 70s to 80 degrees in the immediate NYC area, and the mid to upper 70s in Long Island and southern Connecticut.


Weekend Outlook: Cloudy, Chilly, Rainy

Behind the cold front tomorrow night, a significantly colder air mass will move into the region from Canada, with a large area of 850 mb temperatures below zero degrees celsius. Unlike what was modeled several days ago, however, the cold will not be able to pour straight into the area. Last night's update mentioned that a low pressure was expected to develop near New Jersey on Saturday, moving into New England on Sunday, due to an upper level low over the region. The latest trends have placed this upper level low further southwest with a stronger surface low, which will result in a stronger low pressure tracking over the area, keeping the cold locked to the SW of the area while bringing warmer temperatures northeast of NYC.

The latest outlook for this weekend is for rain to develop across the area after 12 AM Friday night. Light to moderate rain will continue through at least Saturday morning, with mostly cloudy to cloudy skies and scattered showers lasting through Sunday as the low pressure moves over NYC. Due to the position of the storm, temperatures will be the coldest further west and the warmest further east, with high temperatures on Sunday expected to reach the lower to mid 50s in NW NJ/SE NY, mid to upper 50s in the immediate NYC area, and the lower 60s in most of Long Island and southern Connecticut. Due to the cloud cover and the location of the low pressure, temperatures on Sunday night will not be as cold as previously thought, staying in the 40s across most of, if not the entire area. The lowest temperatures will be in the upper 30s to lower 40s in NW NJ/SE NY. Temperatures will slightly warm up for Monday, reaching the mid 50s to lower 60s across the area.


Longer Range: A more detailed, longer discussion will be posted on Saturday morning, discussing the latest expectation for this weekend as well as an update on the Northeast snow potential. The main focus of the discussion, however, will be on next week into next weekend, as a second cool down in the middle of next week may be followed by a significant warm spell by next weekend. More information on that, as well as the potential scenarios, will be posted on Saturday morning.

Sept 29, 2011 Storm Updates

Below, short updates on the rain and thunderstorms affecting the area will be posted throughout the day.

*Short term graphics will be posted below. Click on the graphics to view them in a larger size.*

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3:20 PM: With the scattered thunderstorms earlier this afternoon clearing the area, the cold front, currently over eastern Pennsylvania, is approaching the area. Ahead of this front is a line of strong to severe thunderstorms, currently stretching down from western Bergen to Somerset counties and moving slowly to the east. This line will affect NE New Jersey and NYC within the next 1/2 hour, and SW Connecticut and Nassau county within the next 1/2 to 1 hour.

2:00 PM: Widespread storms continue to affect the area. The strongest storm is currently near SE Warren county and is moving to the NNE/north, and is capable of producing strong wind gusts and heavy rain. A line of training storms continues to remain over NW NJ, with scattered thunderstorms near the coast of southern Connecticut and moving NE. Otherwise, the rest of the area will stay dry over the next 1/2 hour with scattered showers.


1:20 PM: The storm previously over NE NJ has moved into south central Westchester county, and will continue to move NE through the rest of Westchester into NW Fairfield county, CT, while slowly weakening. Meanwhile, a line of heavy thunderstorms has formed near NW NJ, and is slowly drifting to the northwest. A line of brief yet heavy thunderstorms has formed over northern Long Island and will move NE/NNE, reaching the coast of southern CT within the next 20-25 minutes, and another strong storm will move into northern Middlesex/Union counties within the next 25-30 minutes. Otherwise, light rain will affect NYC and western Long Island.


12:55 PM: The strong thunderstorm previously mentioned is currently over SE Bergen County, near Fort Lee, and is moving NE. This storm will affect eastern Bergen, SE Rockland, and Westchester counties over the next 15-30 minutes with heavy rainfall, strong wind gusts, and small hail.


12:20 PM: A strong thunderstorm has formed near eastern Union county, and is moving towards the NNE. This storm is capable of producing strong wind gusts, heavy rainfall, and small hail. Within the next 1/2 hour, this storm will affect Manhattan and Bronx in NYC, Eastern Essex and Eastern Bergen in NJ, and SE Rockland and Westchester counties in SE NY. In addition, a weak thunderstorm is also located over NE Warren county, and will move north into central Sussex county.


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10:00 AM: Thunderstorms, Potentially Strong, Expected Today


Last night, a round of moderate rain and thunderstorms affected the western half of the area, bringing rain totals up to at least 1/2 to 1 inch in Rockland/West Passaic counties,1.5 to 3.5 inches in NW NJ and Orange County, NY, and 1/2 to 1 inch from eastern Suffolk county into south central Connecticut. The rest of the area generally saw up to 1/4 inch of rain.

The original outlook for today was for cloudy skies with occasional showers. Instead, however, the cloud cover has cleared in parts of the area, and temperatures are rising along with humidity and instability. When combined with a lift index of -5 and bulk shear up to 45-50 knots, scattered strong thunderstorms are expected to form in Pennsylvania and affect the area, especially from NYC and further north/west, between 2 and 6 PM. The main risk with these storms will be gusty winds, with small hail also a potential risk with these storms. In places that will be affected by these storms, at least 1/4 to 1/2 inch of rain is expected with locally higher amounts. Due to the decreased cloud cover, temperatures will be warmer as well, peaking in the mid to upper 70s inland and the upper 70s to lower 80s in the immediate NYC area.

The storms are expected to end by this evening, with clearing skies for the overnight hours. Occasional updates will be posted today, with the next full update tonight discussing the storm expected to affect the area on Saturday, the cold temperatures on Sunday, and the outlook for next week into next weekend, going from a potential second cold spell to a warm spell.

Wednesday, September 28, 2011

Sept 28, 2011: Winter-Like Start To October

The cut off low which brought widespread clouds to the region over the last day started to drift to the east, bringing the rain bands further east along with colder temperatures and lower humidity. Most of the area saw a few showers with cloudy skies, but the western parts of the area saw an unexpected round of heavy rain this morning, with as much as 1-2.5 inches of rain falling in parts of Sussex and Orange county. High temperatures today were slightly cooler than yesterday as a result of the increased cloud cover and rain, peaking in the upper 60s to lower 70s inland, mid 70s in the immediate NYC area, and the lower to mid 70s in Long Island and southern Connecticut.

The cut off low will continue to drift to the east, bringing more widespread showers into the area for tonight into Thursday, with a period of moderate to heavy rain possible in parts of the area. As this cold front pushes to the east of the area, cloud cover will clear with drying conditions for Thursday night, but another cold front will then push through the area on Friday night. Behind this front, the coldest air mass of this fall so far will move into the region, bringing high temperatures into the 50s across most of the area for Sunday, and when combined with a low pressure, the potential is there for the first snow of the season to fall in parts of New York state and Pennsylvania.


Tomorrow's Outlook:

As previously mentioned, the cut off low drifting east will bring widespread rain back into the area. With 850 mb temperatures similar to those of today, near 13-14 degrees celsius, along with cloudy skies and rain, temperatures will be similar to those of today but slightly warmer, peaking in the mid 70s inland, mid to upper 70s in the immediate NYC area, and in the mid 70s across most of Long Island and southern Connecticut.

Occasional showers are expected to fall throughout the day today, with light to moderate rain affecting the area. Occasionally, especially during the middle of the day, locally heavy showers may be possible from NYC and further west. No significant rain amounts like those of Friday are expected, but rainfall amounts between 1/2 and 1 inch are expected across the area, with amounts locally up to 1.5 inch from NYC and further west. Storm updates will be posted during the day tomorrow when necessary.


Friday - Weekend: Cooling Down, Some Rain Expected

The cold front will move through on Thursday night, bringing clearing skies and drier conditions, with partly cloudy skies returning by Friday. Meanwhile, another front will approach the area from the west, which will move through by Friday night. This will keep warm temperatures in place during the day on Friday, with high temperatures expected to reach the lower to mid 70s inland, mid to upper 70s in the immediate NYC area, and the mid 70s in Long Island/S CT. Isolated showers are possible, but widespread rain is not expected.

For the weekend, a much colder air mass will move in from Canada. Meanwhile, an upper level low will form over the region, which will result in a weak surface low providing widespread showers across the region while trapping the colder temperatures aloft over the Mid Atlantic into Pennsylvania and parts of New York. This will produce scattered showers for the area on Saturday potentially into Sunday, with up to 1/4 to 1/2 inch of rain likely to fall, but no significant rain is expected, and the showers are mostly expected to be scattered. With the showers moving into the area of below freezing 850 mb temperatures, however, the potential is there that the first flakes of the season may fall in the higher elevations of New York and Pennsylvania. More information will be posted on this potential over the next few days.

In the NYC area, this cold spell will bring colder than average temperatures to start October. High temperatures on Saturday will reach the lower 60s inland and the mid 60s across the rest of the area. Due to the cloud cover on Saturday night, temperatures will drop into the 40s across most of the area with lower 40s inland and lower 50s in NYC. Sunday will be the coldest day, as cloud cover, cold 850 mb temperatures near zero degrees celsius, and scattered showers will keep temperatures below the 60 degree mark across most of, if not all of the NYC area. At this time, I am expecting temperatures to peak in the mid 50s in the western parts of the area and the mid to upper 50s from the immediate NYC area and further east; this is conservative when compared to the majority of the models, which are most likely overestimating the intensity of the cold air by showing high temperatures in the upper 40s to lower 50s across most of the area.

The coldest night will be on Sunday night, when the cold air mass starts to weaken. 850 mb temperatures will remain cold, near zero degrees celsius, which combined with less cloud cover and no risk of rain, will allow for the coldest temperatures of the cold spell to affect the area. Low temperatures are expected to drop below 50 degrees across the area, including NYC, which should see lows in the mid-upper 40s, with low temperatures reaching the 30s in parts of NW NJ/SE NY. Low temperatures in the lower 40s are possible as far as the immediate north/west suburbs of NYC in the colder case scenario.


Next Week: Warm Up Or Another Cold Spell?


As the trough will push out of the region by Monday, a surge of warmth will move in from the west, bringing warmer temperatures for Monday, reaching the upper 50s to mid 60s across the area, and even warmer temperatures for Tuesday, reaching the upper 60s to lower 70s across the area, potentially slightly warmer. Afterwards, however, uncertainty increases for the middle to the end of next week as a trough from Canada approaches the region. Some models keep this trough to the north of the area while bringing warmer than average temperatures into NYC, reaching the upper 70s, while others drop the trough to cover the entire region, with temperatures returning into the lower 60s for highs. The model ensemble means have been consistent for the last 2 days with dropping this trough into the region, and some of the main models, such as the GFS and ECMWF, are trending towards this scenario as well.

At this time, I expect this trough to mostly affect the interior Northeast with the NYC area close to the southern edge of the cold air mass, with temperatures slightly dropping, potentially into the mid-upper 60s range for highs, with temperatures potentially warming up again by the end of next week as the trough is likely to exit the region. Regardless of whether the cold or warm scenario verifies, however, dry conditions with sunshine are expected for next week as a large high pressure spreads across the region. Stay tuned for more information on next week's outlook over the next few days.

Tuesday, September 27, 2011

Sept 27, 2011: Cold Start To October

With a cut off low remaining stationary over the Ohio Valley, today brought conditions similar to those of the last three days, with mostly cloudy skies and warm/humid conditions observed once again. High temperatures were slightly cooler than those of yesterday, peaking in the upper 70s to lower 80s from NYC and further west and in the upper 70s across most of Long Island and southern Connecticut.

The cut off low will begin to drift further east on Wednesday, which will push the rain further east once again, bringing rain back into the NYC area for Wednesday and Wednesday night. As the cut off low merges with another low pressure in Canada, a cold front will move through on Thursday bringing more widespread moderate to heavy rain. Behind the front, temperatures will cool down on Friday with clearing skies, but as a colder air mass moves in from Canada, temperatures will significantly cool down for next weekend, bringing an unseasonably cool start to October.


Tomorrow's Outlook:

Tomorrow will bring colder temperatures into the area. As the upper level low begins to shift further east, the rain bands will move slightly to the east as well, affecting central Virginia into central/western New York. 850 mb temperatures will once again remain near 14-15 degrees celsius, but cloudy skies are expected along with scattered showers, which will lower the temperatures once again. High temperatures will peak in the lower 70s inland, mid 70s in the immediate NYC area, and in the lower to mid 70s across most of Long Island and southern Connecticut with an east wind expected.


Thursday - Friday: Rain Continues

As the upper level low continues to slowly drift east, reaching Ohio by Thursday, the rain bands will begin to shift east as well. With the storm starting to merge with another storm dropping down from Canada, a stronger cold front will move through the area late on Thursday, bringing a widespread moderate to locally heavy rain event across the area. This rain will not be as heavy as last Friday's rain event, but regardless, rainfall amounts are expected to end up between 1/2 and 1 inch across the area with amounts locally as high as 1.5 inch west of NYC. Due to the cloud cover and rain, temperatures will be cool once again, peaking in the lower to mid 70s across most of the area with a few upper 70s in the immediate NYC area.

With the cold front moving through the area, Friday will bring drier conditions with partly to mostly cloudy skies. Isolated showers cannot be ruled out, but overall, Friday will be much drier than Thursday. As the storm from Canada, merged with the upper level low, continues to organize itself, another cold front will move towards the area on Friday, which will keep mild temperatures in place, with high temperatures peaking in the lower 70s inland and in the mid 70s across the rest of the area. A few upper 70s may be possible near NYC in the warmer case scenario.


Next Weekend: Cold Start To October

The combination of the Canadian storm and the upper level low will help pull in a strong trough from Canada. 850 mb temperatures are expected to be as low as -8 degrees celsius with this air mass when it enters the north central US. With the second front moving through the area on Friday night, temperatures will be cooler on Saturday, peaking in the lower to mid 60s inland and in the mid 60s acrosss the rest of the area. Meanwhile, the cold air mass will dig into the western parts of the region, and will slowly approach the area.

With the front not too far offshore and an upper level low expected over the region, the cold air mass will weaken as it reaches the area, with 850 mb temperatures expected to end up near zero degrees celsius across the area. When combined with partly to mostly cloudy skies and a northwest wind, this will produce unusually chilly temperatures. Saturday night will be the coldest night, with temperatures expected to drop into the 30s inland and into the lower 40s potentially as far as the immediate north/west suburbs of NYC. For Sunday, temperatures are expected to peak in the 50s across the area, likely in the lower to mid 50s inland and the mid to upper 50s in the rest of the area. Stay tuned for more information on the cold spell for this weekend.


Next Week: Warming Up


This cold spell will only be short lived. As the image above shows, warmth will push in from the west once this cold spell will end, bringing a surge of warmth into the region along with a high pressure providing the area with sunshine and dry conditions for next week. Uncertainty comes into the picture when another trough from Canada becomes involved, however, as some models push this trough straight into the region, keeping any warmth short lived, while other models keep the warmth locked over the region, bringing a significant surge of warmth. There is still time for this scenario to change, but at this time, I am expecting the trough to mostly affect the Northeast, with places from NYC and further west/south affected by this surge of warmth more directly. Temperatures should warm up into the 70s again by the middle of next week, with parts of the Mid Atlantic expected to reach the 80s. If the warmer case scenario verifies, temperatures into the lower 80s may get as far north as NYC, but this is highly uncertain and depends on the location of the trough. Stay tuned for more information on next week's outlook.

Monday, September 26, 2011

Sept 26, 2011: Cloudy/Wet Pattern To Continue

Note: The 5-Day Forecast page was updated tonight for the immediate NYC area. On Tuesday, the page will be updated for the rest of the area as well.

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The cut off low which previously affected the region with rain remained stationary over the western Ohio Valley, producing rain over that region, while a high pressure over the region kept mostly cloudy skies and a warm/humid air mass in place. High temperatures were warmer than average once again, reaching the lower 80s inland, lower to mid 80s in the immediate NYC area, and the upper 70s to lower 80s in Long Island and southern Connecticut.

As the cut off low begins to drift east, rain will return into the area for Wednesday and Thursday, with up to an additional inch of rain expected across the area. As the cut off low phases with another storm in Canada, a colder air mass will drop into the region for the weekend, but with an upper level low in place, however, rain chances may continue through the weekend as well.


Tomorrow's Outlook:

With the high pressure sticking over the region, tomorrow will bring mostly cloudy skies once again to the area with a SE wind. 850 mb temperatures will remain around where they were today, near 14-15 degrees celsius, but more cloud cover than today is expected with a slight risk of an isolated shower in the western half of the area. With the factors above, temperatures will be slightly cooler than they were today, reaching the upper 70s inland, upper 70s to lower 80s in the immediate NYC area, and the upper 70s across most of Long Island and southern Connecticut.


Wednesday - Friday: Clouds Persist, Rain Returns

Over the last few days, the cut off low was well to our west, keeping the area dry, but as the storm will begin to slowly drift further east, rain chances will begin to increase by Tuesday night. The cut off low's cold front will approach the area on Wednesday before moving through on Thursday, which will spread the rain further east, from the Ohio Valley into the Northeast. This scenario will bring rain back into the area. Occasional showers will develop on Wednesday, and will become more widespread by Wednesday night into Thursday, with heavier rainfall amounts expected. By the time that this round of rain ends around Thursday night, an additional 1/2 to 1.25 inch of rain is expected across the area, with locally higher amounts possible north/west of NYC.

By Friday, the cut off low will merge with another low pressure in Canada, which will help to pull a strong cold air mass into the north central US. This will bring another cold front through the area. This cold front is expected to be drier, bringing mostly cloudy skies to the area with isolated showers. High temperatures will be slightly cooler, peaking in the upper 60s to mid 70s across the area.


Next Weekend - Next Week: Cold, Then Warming Up


As the front pushes to the east of the area, a colder air mass will move in, with 850 mb temperatures dropping below zero degrees celsius in the Great Lakes, Ohio Valley, and parts of the Northeast. Unlike yesterday, when most models showed a high pressure moving in with dry conditions, however, the latest trend has been to show an upper level low slowing down over the region during the weekend. The models continue to differ with the scenario at the surface, ranging from the CMC showing a fully developed cut off low over the US, to the GFS with a moderate coastal low near New England, to the ECMWF with no well defined surface low.

Given the recent trends we have seen and the current pattern we are in, I am currently expecting a scenario where the upper level low moves over the region with a weak surface low, producing partly to mostly cloudy skies and scattered showers from the NYC area and further north and east, but widespread moderate-heavy rain is not expected at this time. This will keep the coldest temperatures to the west of the area, with places such as Washington DC potentially ending up colder than places further east such as NYC/Boston. Regardless of the storm, colder temperatures are expected for the weekend, with high temperatures likely to peak in the 50s across parts of, if not most of the area on Sunday. Stay tuned for more information on the cool down and potential storm for next weekend.

By next week, the cold air mass will be driven out of the region as a warmer air mass from the western US spreads further east. As this is in the longer range, there is more uncertainty, but the latest teleconnections as well as the pattern suggest that the potential may be there for another widespread warm up across the region next week. More information will be posted as details become clearer.

Sunday, September 25, 2011

Sept 25, 2011: Another Week Of Clouds And Rain

Note: I was able to create a discussion for tonight, but due to technical difficulties, the pages were not updated tonight. By Tuesday afternoon, there should be an update in every page except for the Long Range Outlooks, which will be updated next weekend with an October/November long range outlook.

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After heavy rain on Friday, which dumped a widespread 1-2 inches of rain across the NYC area, a high pressure building into the region provided the area with a mainly cloudy yet dry weekend, with high temperatures peaking today in the upper 70s inland, lower 80s in the immediate NYC area, and the upper 70s to lower 80s in the immediate NYC area. These high temperatures are slightly above the average for this time of the year, which are approximately in the lower 70s. The low temperatures, however, had a much more remarkable departure from the average, which is also a factor contributing to a warmer than average September. In Central Park, for example, the low temperature this morning was 70 degrees while the average is 57 degrees; this is 13 degrees above the average low.

The cut off low is currently located over the western Ohio Valley, which is keeping the rain and cool temperatures to the west of the region while locking the NYC area under a warm and humid air mass. As the cut off low begins to drift east by the middle of this week, temperatures will cool down with widespread rain returning into the area by Wednesday. The cut off low will finally exit the region by Friday, but will be followed by a strong cold front which, if the latest models are correct, could bring the coldest temperatures yet this fall.


Tomorrow's Outlook:

With the cut off low remaining to the west of the region, over the western Ohio Valley, tomorrow will be another mostly cloudy, humid and dry day with a slight risk of an isolated shower. 850 mb temperatures will be near 15-16 degrees celsius, resulting in surface temperatures reaching the upper 70s to lower 80s inland, lower 80s in the immediate NYC area, and the upper 70s to lower 80s in Long Island and southern Connecticut. A SE wind is expected.


Tuesday - Thursday: Cut Off Low Drifts East; Rain Returns

The cut off low will begin to drift to the east on Tuesday, which will bring more cloud cover and slightly cooler temperatures into the area. The rain will still stay mostly to the west of the area, however, with temperatures expected to peak in the mid 70s to the lower 80s across the area, but there should be a slightly higher risk of showers across the western half of the area.

By Wednesday and Thursday, the storm will drift far east enough to bring more widespread rain into the area. Widespread heavy rain like that of Friday is not expected, but occasional light to moderate rain is expected, which should bring an additional 1/4 to 1 inch of rain across the area. Temperatures will cool down as well, reaching the lower to upper 70s across the area.

The cut off low will merge with a storm in Canada on Friday. This will result in a strong cold air mass from Canada starting to drop south into the north central US. The storm's cold front is expected to move through the area on Friday, keeping temperatures in the 70s while bringing another risk of showers across the area, but the entire system is finally expected to leave the region on Friday night, with clearing skies and dropping temperatures.

For next weekend, the latest models are in an agreement with showing a significantly colder air mass, with 850 mb temperatures dropping below zero degrees celsius, especially the GFS model. The GFS is likely overestimating the intensity of the cold air, showing high temperatures in the 40s across parts of the area with low temperatures in the lower 30s inland. Considering the time of the year and the GFS' bias to overestimate cold air, this is most likely too cold, but should the latest scenario come close to verifying, the area may see high temperatures in the 50s by next weekend. Stay tuned for more information on the potential cool spell for next weekend.

Saturday, September 24, 2011

**No Update Posted 9/24/11**

The blog was not updated today. The next update will be posted on Sunday evening.

Friday, September 23, 2011

Sept 23, 2011: Rain To Weaken Tonight

Note: A brief update was posted tonight, with the other pages not updated for tonight's update. The 5-Day Forecast, Tropics and Weather Alerts pages will be updated this weekend, either tomorrow or on Sunday.

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A surge of tropical moisture moved up the East Coast today, bringing widespread heavy rain into the region, including the area from NYC and further west, where anywhere from 1/2 to nearly 2 inches of rain fell. In the eastern parts of the area, however, less rain fell as the storm ended up further west than expected, with only 1/4 to 1 inch of rain in Long Island and most of southern Connecticut. Due to the rain, temperatures peaked in the lower 70s inland, mid 70s in the immediate NYC area, and the lower to mid 70s in Long Island and southern Connecticut.

With the current round of rain moving out of the area by 12-2 AM tonight, a high pressure is expected to briefly enter the region, which will bring mostly cloudy skies into the area for the weekend with above average temperatures and the risk of an isolated shower. As the cut off low drifts back east next week, rain will return into the area for early-mid next week before the storm finally exits the region late next week.


Weekend Outlook

As the rain moves out of the region tonight, cloud cover will clear for Saturday, with mostly to potentially partly cloudy skies expected along with isolated showers. With the clearing of the cloud cover, temperatures will warm up, reaching the mid to upper 70s across the area. Should the weekend bring partly sunny skies, temperatures will likely reach the lower 80s in parts of NE NJ, which is warmer than the average for this time of the year. Similar conditions are expected for Sunday, but with slightly more cloud cover and a more widespread shower risk.


Next Week: Rain Returns, Ends By Thursday

The upper level low will remain stationary over the western Ohio Valley through Monday, keeping most of the rain to the west of the NYC area while bringing conditions similar to those of the weekend. By Tuesday, however, the upper level low will begin to drift to the east, which will bring mostly cloudy to cloudy skies with occasional showers from Tuesday through Wednesday, potentially including Thursday. Temperatures will gradually cool down, into the mid 70s across most of the area by Wednesday.

By the end of next week into next weekend, the storm is finally expected to move out of the region as it merges back into the main flow. Meanwhile, a stronger storm from Canda is expected to move further south than the previous storms in central Canada, and most of the latest models are showing a strong cold air mass pushing south from Canada into the NE US, in a position favorable for more sustained chilly temperatures for the start of October. There is still uncertainty with the longer range, but the potential for colder than average temperatures for next weekend will be watched. More information will be posted on the longer range as details become clearer.

Sept 23, 2011 Storm Updates

Below, storm updates will be posted on the heavy rain event currently affecting the region.

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6:35 PM: Rain Starts To Intensify Again

The break in the rain earlier this afternoon is now ending as another round of rain, previously over SE Virginia, is moving into New Jersey. Even though the heavier rain is currently affecting eastern PA, the rain axis is gradually shifting to the east, and thunderstorms near the southern Delmarva Peninsula will affect Long Island this evening into the early overnight hours. Moderate to heavy rain will affect the area this evening, and is expected to end by at least 12-2 AM across the area with cloudy skies and scattered showers for the rest of the overnight hours. By the time that the storm ends, an additional 1/2 to 1 inch of rain is expected to fall across the area.



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4:10 PM: Heavy Rain Continues


Since the late morning hours, widespread moderate to heavy rain affected places from NYC and further west, while places further east such as Long Island and southern Connecticut saw light to moderate rain. The latest rain totals shown by the radar estimates show that at least 1/2 to 1 inch of rain fell from NYC and further west, with 0.1 to 1/2 inch in Long Island and southern Connecticut.

As the rain totals above and the radar image to the left suggest, the storm ended up further west than expected. With last night's update, I drew a rain map that went close to the westernmost model solutions, but the axis of heavy rain still ended up slightly further west, as Long Island and southern Connecticut saw much less rain than expected while places in central Pennsylvania and New York saw more rain than expected.

Looking at the latest radar image, the area has mostly dried up, with light rain currently affecting most of the area other than some moderate rain in parts of southern Connecticut. This break in the rain will continue through at least 6-7 PM, when another round of heavy rain will move into the area from the Delmarva Peninsula. As with this morning, the heaviest rain will stay from NYC and further west, with lighter rain amounts affecting Long Island and southern Connecticut. An additional 3/4 to 1.5 inch of rain is expected to fall from NYC and further west, with another 1/2 to 3/4 inch of rain in Long Island and southern Connecticut. Stay tuned for more storm updates throughout this afternoon and evening.

Thursday, September 22, 2011

Sept 22, 2011: Heavy Rain Tomorrow, Saturday

After a round of light rain last night, with rainfall amounts mostly falling up to 1/4 inch except for parts of NW NJ and SE NY, which saw up to 1/2 inch of rain, today brought drier conditions to the area with mostly cloudy skies. With the breaks in the cloud cover, temperatures were slightly warmer than expected, peaking in the upper 70s to lower 80s from NYC and further west and the mid to upper 70s in Long Island and southern Connecticut.

A surge of tropical moisture will move up the coast through tomorrow and Saturday, bringing heavy rain into the area from Friday afternoon through Saturday morning, with 1 to 3 inches of rain expected. Even though the heaviest rain of this time frame is expected to fall on Friday night, scattered showers are possible through the weekend, with occasional showers early-mid next week as the cut off low begins to exit the region. With the cut off low only slightly drifting out of the region, rain chances will continue well into next week.


Tomorrow's Outlook:

Tomorrow will bring cloudy skies to the area with a SE wind expected. Due to the cloud cover and rain, especially during the second half of the day, temperatures will be slightly cooler than those of today, peaking in the mid 70s across most of the area with a few upper 70s possible in parts of NE NJ in the warmer case scenario.

Looking at the regional radar in the Southeast US, rain and thunderstorms are covering a wide part of the region as a surge of tropical moisture is moving up the coast. This moisture will affect the area tomorrow into Saturday morning, with precipitable water values reaching 2 inches, easily capable of producing heavy rainfall. Cloudy skies with a few showers are expected for Friday morning, with steadier rain developing by the afternoon and evening hours. The rain will be occasionally heavy at times, especially in the immediate NYC area. Moderate to occasionally heavy rain will continue through Friday night and into Saturday morning before weakening by Saturday afternoon.

Rainfall amounts are expected to end up between 1.5 and 3 inches by Saturday afternoon across the area. Above, I posted a rain map showing my current thoughts on where the heavier rain will end up. It is a possibility that the 1-2" and the 2"+ inch zones may have to be moved further east than shown above. Stay tuned for storm updates which will be posted throughout the late afternoon and evening on Friday.


Weekend - Next Week: Rain Continues

The cut off low expected to form over the Ohio Valley will not be quick to leave. The main flow of storms will move through central Canada, and with no feature expected to drop far south enough to reach the cut off low until the middle of next week, the cut off low will remain stationary over the Ohio Valley through next Wednesday, keeping a risk of scattered showers in the forecast through Wednesday or Thursday. The rest of the weekend will bring an improvement in the conditions, however, as mostly cloudy skies are expected with scattered showers and temperatures peaking in the mid to upper 70s across the area, potentially reaching the 80 degree mark in parts of NE NJ if there is more sunshine than currently expected.

By early next week, another low pressure will form around the cut off low, and will produce more rain across the region. This time, the heavier rain is expected to fall to the west of the area, but occasional showers are still expected from Monday through Wednesday, with an additional 1/4 to 3/4 inch of rain expected through Wednesday. Should the storm end up further east or wetter than currently expected, amounts may pass 1 inch in parts of the area early-mid next week. Stay tuned for more information on the additional rainfall for early next week.

By the middle of next week, a storm in Canada is expected to finally pick up the cut off low, taking it away from the region. The models differ with the details regarding how the cut off low leaves, with solutions ranging from a cold air mass dropping into the region, bringing high temperatures down into the 60s, to the cold air mass leaving the region with warmer temperatures building back in, with highs staying in the mid-upper 70s. Stay tuned for more information on the longer range.

Wednesday, September 21, 2011

Sept 21, 2011: Wet Ending To September

As a front cleared the area last night, mostly cloudy skies were observed across the area today. A warmer air mass moved into the region, which brought warmer temperatures as well, peaking in the mid 70s across the entire area with a few upper 70s in the immediate NYC area. Scattered showers were observed as well, with less than 0.1 inch falling in places that did see rain today.

As an upper level low will begin to form over the Ohio Valley, moisture will move up the coast, with additional light rain expected tonight, amounting up to 1/4 inch in most areas, locally up to 1/2 inch. Moisture moving up from the tropics will bring more widespread moderate to heavy rain for Friday, however, with rainfall amounts exceeding the 2 inch mark in parts of the area by Friday night. With the upper level low sticking around over the region through the middle of next week, rain will remain in the forecast through mid-late next week, and by the time that the cut off low leaves the region sometime mid-late next week, as much as 3-5 inches of rain may be possible in parts of the area, bringing September's rain totals well above the average.


Tomorrow's Outlook:

Tomorrow will bring cloudy to mostly cloudy skies across the area. The showers expected for tonight will end up to the north of the area, though isolated showers are still possible throughout the day on Thursday, which could accumulate up to 1/4 inch. With a SSE/south wind expected, temperatures will be similar to those of today, peaking in the mid to upper 70s from NYC and further west and in the lower to mid 70s in Long Island and southern Connecticut.


Heavy Rain On Friday, Showers For Weekend

A surge of moisture is expected to move up the East Coast on Friday into Friday night as the cut off low develops over the Ohio Valley and tropical moisture begins to move up the coast. Steady rain will begin to develop across the area early on Friday morning, with the heavier rain expected to begin after noon and end around 12 AM. There is some slight uncertainty with the location of the heaviest rain, as the models up to this morning indicated that the heaviest rain would be east of NYC, but now show the heavier rain to also affect places west of NYC. For tonight's forecast, I am expecting moderate to heavy rain across the area, with rain totals by Saturday morning between 1 and 3 inches across the area.

Drier conditions will return for Saturday and Sunday as the main round of rain moves out of the area. Mostly cloudy skies will continue for both days with scattered showers bringing up to at least 1/4 inch each day, and with the upper level low still to the west of the region, mild temperatures will continue, peaking in the mid to upper 70s from NYC and further west, and the lower to mid 70s east of NYC.


Next Week: Rain Continues

Another low pressure is expected to form around the upper level low early next week, which will bring more rain into the area. As the upper level low will begin to drift to the east, the rain will shift to the east as well, with the heaviest rain expected to fall from NYC and further north and east, and while there is uncertainty with amounts, at this time it appears that another 1/2 to 2 inches of rain may fall early next week. Stay tuned for more information on the rain totals for the potential rain event early next week.

It appears at this time that the upper level low should exit the region around Wednesday/Thursday, with drying conditions by Thursday and Friday. There is still uncertainty with the timing, however, which could be earlier or later than expected. Stay tuned for more information on next week's outlook with tomorrow's update.

Tuesday, September 20, 2011

Sept 20, 2011: Week Of Rain Starts Tomorrow

The stretch of mostly dry weather since the remnants of Tropical Storm Lee finally ended today as a cold front approached the area, bringing light rain up to 0.1 inch across the area. High temperatures were chilly due to the cloud cover and rain, peaking in the mid to upper 60s inland, upper 60s to lower 70s in the immediate NYC area, and the upper 60s across most of Long Island and southern Connecticut.

Today is just the start of what will be a long stretch of cloudy skies and rain, with rain expected to fall at some point during each day for the next 8 days. It will not rain consistently during this entire time frame; the rain is expected to come in waves, with light to moderate rain on Wednesday night, moderate/heavy rain on Friday, and another potential round of moderate/heavy rain next week. When combined, rain totals may exceed 3-5 inches across parts of the area, resulting in flooding potentials once again.


Tomorrow's Outlook:

With the rain out of the area, tomorrow will bring mostly cloudy skies with the risk of an isolated showers. Temperatures aloft will be warmer, however, with 850 mb temperatures near 14 degrees celsius. A SSE wind is expected, which combined with mostly cloudy skies, will result in temperatures warming up into the 70s across the area for the first time since last Thursday. Temperatures tomorrow will reach the mid to upper 70s from NYC and further west, and the lower to mid 70s in Long Island and southern Connecticut due to the onshore wind.


Wednesday Night - Friday: 3+ Inches Of Rain Possible

A low pressure near the Great Lakes will bring a cold front towards the region, but this cold front will slow down as a cut off low pressure develops near the Ohio Valley on Thursday and Friday. This will bring moisture up the coast, with high precipitable water values bringing the potential for heavy rainfall. Rain is not expected to fall in this entire time frame, but the rain is expected to affect the area in waves. The first wave of rain will affect the NYC area on Wednesday night, bringing widespread light to moderate rain across the area. Rainfall amounts between 1/4 and 1/2 inch are expected across the area.

Behind this wave of rain, mostly cloudy to cloudy skies with isolated showers are expected for Thursday and Thursday night. With 850 mb temperatures warming to 15-16 degrees celsius, surface temperatures will be slightly warmer than those of tomorrow, reaching the upper 70s to potentially the lower 80s in the immediate NYC area.

Mostly dry conditions will continue through most of Thursday night. By Friday morning, however, a wave of low pressure will begin to move up the coast towards the area, and with moisture moving up the coast as well with precipitable water values nearing 2 inches, heavy rain is expected across the area. Rain will begin to develop around Friday morning and intensify, with moderate to heavy rain expected through most of Friday into the early overnight hours. There is some uncertainty with the exact timing, but the overall idea is there that the heaviest rain will fall around Friday. Thunder is expected as well. By the time that this wave of rain will end on Friday night, a total of 1.5 to 3 inches of rain are expected across most of the area, with amounts locally as high as 4 inches of rain. The heaviest rain is expected to fall in the immediate NYC area, Long Island and southern Connecticut. Stay tuned for more information on Friday's rain event.


Saturday - Next Week: Clouds, Rain Continue

The heavier rain will end by Friday night, with drier conditions returning for the weekend. Mostly cloudy skies are expected for Saturday and Sunday, but the risk of isolated showers will continue throughout the weekend. The cut off low previously mentioned will remain stuck over the Ohio Valley, however, and with the main flow of storms moving through central Canada, well north of the US, there will be no feature to take the cut off low out of the region, and it will remain stationary over the Ohio Valley through next week. Due to the cut off low staying to the west of the area, the colder air mass will be stuck over the Ohio Valley, and mild 850 mb temperatures will continue across the area, with temperatures peaking in the mid to upper 70s across most of the area.

With the cut off low slow to exit the region, rain will continue into early next week as well. The latest models show another low pressure developing around Monday/Tuesday, which may bring another round of moderate to potentially heavy rain across the area between Monday and Wednesday. The cut off low is then modeled to slowly begin to exit the region, finally leaving the United States around Thursday with drier conditions returning. There is more uncertainty for next week, however, as the models differ with how they handle the potential storm early next week ,as well as when and how the cut off low exits the region. Stay tuned for more information on next week with tomorrow's update.

Monday, September 19, 2011

Sept 19, 2011: Heavy Rain Potential For Friday

As a high pressure spread from New England into the NYC area, today brought mostly sunny skies to the area. Temperatures were chilly as the leftovers of the cold air mass stayed in place, with high temperatures reaching the mid 60s inland, upper 60s to 70 degrees in the immediate NYC area, and the upper 60s across most of Long Island and southern Connecticut. Due to the mainly clear cloud cover and the high pressure in place, temperatures this morning were chilly as well, with parts of NW NJ and SE NY dropping into the upper 30s for lows.

An approaching front will bring an end to the stretch of dry weather, however. Almost half a month after the remnants of Tropical Storm Lee brought heavy rain into the region, a slow moving front combined with a cut off low will affect the region, producing moderate to locally heavy rain for the second half of this week, with the potential for 1 to 3 inches of rain to affect the area. With the pattern in place, the cut off low will stay stationary, keeping a risk of showers in place through this weekend and into early next week.


Tomorrow's Outlook:

A front will approach the area tomorrow, bringing cloudy skies along with scattered showers. Most of the rain will fall west of NYC, as the rain will start to weaken once it reaches NYC and is expected to fall apart by the time that it reaches Long Island and southern Connecticut. Mostly light rainfall amounts are expected, with 0.1 to 1/4 inch of rain from NYC and further west with lighter amounts east of NYC. Due to the cloud cover, rain, and an expected SSW wind, temperatures will stay chilly, peaking in the mid to upper 60s inland and the upper 60s to lower 70s in the immediate NYC area, Long Island, and southern Connecticut.


Wednesday - Friday: Cutoff Low Brings Heavy Rain Potential

Cloud cover will clear on Tuesday night as the rain dissipates, with partly to mostly cloudy skies expected for Wednesday with a SSE wind expected. Combined with warmer temperatures aloft, with 850 mb temperatures reaching 10-14 degrees celsius, temperatures will warm up across the area, reaching the mid to upper 70s from NYC and further west, and the lower to mid 70s in Long Island and southern Connecticut. Parts of NE NJ may get close to the 80 degree mark.

Isolated showers are possible across the area on Wednesday, but chances for rain will increase by the end of the week. A low pressure will move through the northern Great Lakes on Wednesday night before moving into Canada, bringing its cold front towards the Ohio Valley. Meanwhile, a cut off low will form over the Ohio Valley by Thursday/Friday. This will bring moisture up the East Coast, with precipitable water values reaching 1.5 to 2 inches, capable of producing heavy rainfall.

There is uncertainty with the individual details with this time frame, as rain is not expected to fall in the entire time frame from Wednesday through Saturday. As with Tropical Storm Lee's remnants earlier this month, occasional periods of moderate to locally heavy rain are expected to affect the area, with most of the models focusing the rain between Thursday night and Friday night. The models are split with the rain totals, with the GFS and NAM/DGEX models showing lighter totals, between 3/4 and 1.5 inch, with the ECMWF and CMC showing wetter solutions, with up to 2-4 inches of rain. With the amount of moisture available and considering that this is a long duration rain event, I decided to side with the wetter models, expecting at least 1 to 2 inches across most of the area with amounts locally as high as 3-4 inches of rain. There is still some uncertainty with this time frame, however, and this forecast is not final. Stay tuned for more information on this storm and how it will affect the NYC area.


Next Weekend - Next Week: Clouds, Rain Stick Around

As previously mentioned, a cut off low is expected to develop over the Ohio Valley around Friday. The main flow of storms, however, will be stuck over central Canada, and there does not appear to be any feature pushing southwards towards the US to pick up this upper level low. As a reuslt, the cut off low is expected to remain stationary over the Ohio Valley through the weekend and into early next week as well. This scenario will keep average temperatures in place as the cold air mass remains stuck over the Ohio Valley, with temperatures reaching the lower to mid 70s across most of the area for the weekend into early next week, potentially getting into the upper 70s near and south of NYC in the warmer case scenario. There is more uncertainty with the rain potential, however, as some models keep dry conditions in place, while others show scattered showers with another storm developing around early next week. Stay tuned for more information on the outlook for next weekend and next week with tomorrow night's update.

Sunday, September 18, 2011

Sept 18, 2011: Rain Returns On Tuesday

As a coastal low near southern Virginia moved out to sea last night and early today, cloud cover cleared across the NYC area as a high pressure in the northern Northeast began to spread towards the area. Partly sunny skies were observed today, with high temperatures peaking in the mid to upper 60s inland, upper 60s to lower 70s in the immediate NYC area, and the upper 60s across most of Long Island and southern Connecticut.

The high pressure will remain over the area tomorrow, with mostly sunny skies and slightly warmer temperatures expected. Meanwhile, cloudy skies will return by Tuesday as a warm front approaches, bringing scattered showers. Behind this front, temperatures will warm up back into the lower to upper 70s across the area, and with a cold front slowly approaching from the west, wet weather will continue throughThursday and Friday.


Tomorrow's Outlook:

The cold air mass that has been over the region for the last few days is slowly weakening, and tomorrow, temperatures aloft will begin to warm up as well, reaching about 5-7 degrees celsius. With the high pressure spreading over the area, mainly sunny skies are expected as well. These factors will allow temperatures to warm up slightly for Monday, reaching the upper 60s inland, upper 60s to lower 70s in the immediate NYC area, and the upper 60s to 70 degrees in most of Long Island and southern Connecticut. An east wind is expected early in the day, switching direction to SE by the late afternoon/evening.


Tuesday - Friday: Warming Up, Rain Returns

An approaching warm front will push the high pressure out of the area, with increasing cloud cover expected for Monday night. By Tuesday, cloudy skies are expected with showers and a south wind. Mostly light rainfall amounts are expected, generally up to 1/4 inch, with the most rain falling to the west of NYC. Due to the rain and cloud cover, temperatures will stay chilly, peaking in the mid to potentially upper 60s inland, upper 60s to potentially lower 70s in the immediate NYC area, and the upper 60s across most of Long Island and southern Connecticut. There is some uncertainty with the temperatures, and less rain or more breaks in the cloud cover could result in warmer temperatures than those mentioned above.

Once the rain ends on Tuesday night, mostly cloudy skies will continue through Wednesday with the risk of isolated showers, but temperatures will warm up, reaching the mid to upper 70s from NYC and further west and the lower to mid 70s in Long Island/S CT. A slow moving cold front will reach the region around Thursday night/Friday, and as the front approaches, occasional showers and thunderstorms are expected from Wednesday night through Thursday night, potentially including Friday if the front slows down from the current expectation. There is some uncertainty with the rain totals, but at this time, it appears that at least 1/2 to 1 inch of rain could fall as a result of this cold front. By the weekend, as the storm exits, partly sunny skies will return with temperatures cooling down into the lower to mid 70s across most of the area. Stay tuned for more information on the late week rain storm.

Saturday, September 17, 2011

Sept 17, 2011: Warmer Temps Slowly Return

As a coastal low pressure developed near the Carolinas today, widespread cloud cover was observed across the region, including the NYC area, as the high pressure ended up further north than first expected, over northern New England. High temperatures were colder than expected as a result of the increased cloud cover, only peaking in the lower 60s inland, lower to mid 60s in the immediate NYC area, and the mid to upper 60s in Long Island and southern Connecticut.

As this coastal low continues to organize itself while moving to the NE, the rain will stay south and east of the NYC area, but mainly cloudy skies will continue tonight before clearing throughout the day on Sunday. Mostly sunny skies will return for Monday as the high pressure spreads back south into the area, but this will be short lived, as an approaching cold front will push the high pressure out and bring mostly cloudy skies and showers to the area for the mid-late week.


Tomorrow's Outlook:

Tomorrow will be another chilly day, but with the coastal low moving out of the region and the high pressure slowly starting to spread from northern New England further south into the area, cloud cover will gradually clear throughout the day. Despite 850 mb temperatures similar to where they were today, at about 4 degrees celsius, the additional sunshine should result in warmer temperatures, peaking in the mid to potentially upper 60s inland, upper 60s in the immediate NYC area, and the mid to upper 60s in Long Island and southern Connecticut along with a NE wind. If there is enough sunshine, places near and south/SW of NYC may reach 70 degrees.


Next Week: Warming Up, Rain Returns

The high pressure will spread back into the area on Monday, which will result in sunny to mostly sunny skies. Temperatures will warm up as well, reaching the upper 60s to lower 70s across the area. By Tuesday, however, a cold front will approach the region, bringing temperatures into the lower to mid 70s from NYC and further west along with mostly cloudy skies and a scattered shower risk. This front will fail to bring colder temperatures into the region, and instead, temperatures will warm up once again on Wednesday, reaching the mid to upper 70s from NYC and further west.

Meanwhile, a low pressure will move through the Great Lakes on Wednesday, with its cold front moving through the central US. The cold front will approach the region on Thursday, bringing similar temperatures to those of Wednesday along with additional showers and thunderstorms, but the front will struggle to move through the region, and a cut off low is likely to form to the west of the region. There is some uncertainty with the cut off low potential, but should this scenario verify, mainly dry conditions are possible for Friday into next weekend with the potential for some showers, and even though temperatures are expected to slightly cool down, likely somewhere around the lower 70s, the true cold will fail to make it into the region. Stay tuned for more information regarding the outlook for the end of next week into next weekend.

Sept 17, 2011 Noon Update

2:30 PM: The forecast from last night mentioned that due to a high pressure over the region, today would bring mostly sunny skies. The high pressure ended up over northern New England, however, and a developing coastal low pressure near the Carolinas was able to spread its cloud cover into the NYC area and as far north as southern New York, and rain in association with this storm is falling as far north as SE Pennsylvania. This area of light rain is moving NE, towards New York City, but the rain is weakening as it is approaching the area of high pressure.

For the rest of today, mostly cloudy skies will continue through the rest of the day with the risk of an isolated shower south and west of NYC. Due to the increased cloud cover, temperatures will peak in the lower 60s inland, in the lower to mid 60s in the immediate NYC area, and the mid 60s in Long Island and southern Connecticut. Mostly cloudy skies will continue through the overnight hours as the coastal low begins to intensify with the rain south of the area, and as the low pressure moves offshore and the high pressure spreads back into the region, skies will clear on Sunday with warmer temperatures. Partly sunny skies will continue on Monday, and the next risk of rain will be on Tuesday.

The next update will be posted tonight, discussing the outlook for the end of next week and next weekend in more details, as well as a brief outlook for the end of September.

Friday, September 16, 2011

Sept 16, 2011: Dry And Chilly Weekend

As a cold front moved through the area yesterday, a significantly colder air mass moved into the region, bringing 850 mb temperatures as low as 2-4 degrees celsius into the area. This resulted in colder than average temperatures, with the overnight lows reaching the lower 40s inland (NW NJ/SE NY), mid to upper 40s in the north/west suburbs of NYC, upper 40s in southern CT, upper 40s to lower 50s in Long Island, and lower 50s in NYC. High temperatures were colder than average as well, peaking in the lower to mid 60s inland, mid to upper 60s in the immediate NYC area, and the mid 60s across most of Long Island and southern Connecticut.

With the cold air mass staying over the area, temperatures similar to those of today, if not slightly warmer, are expected for tonight into Saturday. Temperatures aloft will begin to warm up by Sunday, with temperatures gradually starting to warm up, but a high pressure in place will prevent rain from falling until Tuesday, when a cold front should approach the region, bringing scattered showers. With the high pressure moving out of the region, a low pressure will affect the region, bringing rain for Wednesday and Thursday.


Tomorrow's Outlook:

With 850 mb temperatures expected to stay around where they were today, around 4 degrees celsius, temperatures are expected to be similar to those of today, but only slightly warmer. High temperatures will peak in the mid 60s in the western parts of the area, and in the mid to upper 60s in the immediate NYC area, Long Island, and southern Connecticut along with a ENE wind.


Sunday - Next Week: Warming Up, Rain Returns

The high pressure will stay over the region for Sunday and Monday as a low pressure forms near the Carolinas and moves offshore, which will keep dry conditions with mostly to partly sunny skies in place for both days. 850 mb temperatures will slowly begin to warm up, and surface temperatures will warm up as well, with high temperatures peaking in the mid 60s to lower 70s across the area on Sunday, and in the upper 60s to lower 70s across most of the area on Monday.

By Tuesday, however, rain will return into the region and potentially the NYC area as well. A cold front will approach the region, with scattered showers affecting especially the western half of the region, towards Pennsylvania, but some showers are possible in the NYC area as well. Temperatures will continue to warm up, reaching the lower to mid 70s from NYC and further west.

There is increasing uncertainty for Wednesday and beyond with each model showing a different solution, but when looking at the overall picture, rain is expected to fall in the area on Wednesday and Thursday as a low pressure system affects the region, with temperatures above average, peaking in the mid to upper 70s across most of the area. After Thursday, there are two main solutions shown at this time; one possibility is that the front clears the region on Friday with a colder air mass moving in, bringing high temperatures back into the 60s. The other possible scenario would keep the front to the west of the area as a cut off low pressure develops, keeping rain in the forecast through Friday and potentially the weekend. Saturday night's update will discuss which scenario is more likely to verify in more details.

Thursday, September 15, 2011

Sept 15, 2011: Dry Conditions To Continue

With a cold front moving through the area today, temperatures were colder than the last few days. Unlike Wednesday, when temperatures reached the mid to upper 80s in the immediate NYC area, today only brought temperatures into the mid to upper 60s NW NJ/SE NY, lower to mid 70s in NE NJ, mid to upper 70s in NYC, and in the upper 70s to lower 80s in Long Island and southern Connecticut. This type of temperature gradient is not something that happens every day, and was a result of the timing of the front, where the eastern parts of the area had more time than the western parts of the area to warm up before the front moved through. The front produced scattered showers across the area, though rainfall amounts mostly stayed below 1/4 inch.

With the front now to the east of the area, temperatures quickly dropped into the 50s across most of the area by the evening hours, and a breezy NW wind has developed, with winds gusting up to 30-35 mph across most of the area. The winds will decrease overnight as temperatures continue to drop, reaching the upper 30s to lower 40s inland, mid 40s in NE NJ and southern CT, mid to upper 40s in Long Island, and upper 40s to lower 50s in NYC. Colder than average high temperatures are expected for tomorrow, and with a strong high pressure moving into the region, temperatures will gradually warm up into the 70s with dry conditions lasting through the middle of next week.


Tomorrow's Outlook:

A much colder air mass will move into the region tonight, bringing colder than average temperatures tomorrow across the area. 850 mb temperatures will be colder than they typically are around this time of the year, dropping down to only 2-4 degrees celsius. In comparison, 850 mb temperatures yesterday were around 15-17 degrees celsius. As a result of the colder temperatures aloft, temperatures will be much colder at the surface than they were today, with high temperatures reaching the lower to mid 60s inland, mid to upper 60s in the immediate NYC area, and the mid to potentially upper 60s in Long Island and southern Connecticut. These temperatures are equivalent to the high temperatures during October.


Weekend Into Next Week: Dry, Slowly Warming Up

With a strong high pressure moving into the region late tomorrow, mostly sunny skies will continue through the weekend across the area. The cold air mass will begin to weaken as the cold air shifts back into Canada, but temperatures will remain below average, with highs reaching the mid to upper 60s across the area on Saturday, and the mid 60s to lower 70s on Sunday.

The high pressure, meanwhile, will be stuck over the region, with no additional storm approaching the region through the middle of next week. A weak low pressure will form near the Carolinas during the weekend, which will produce showers in the Carolinas and southern Virginia before starting to move offshore next week, but the high pressure will block the storm from moving north towards the NYC area. As a result of the high pressure, mostly to partly sunny skies will continue through at least Wednesday next week with no rain expected. Temperatures will gradually warm up with each day, reaching the lower to mid 70s in NW NJ/SE NY and the mid to upper 70s across the rest of the area by Wednesday.

By the end of next week, there is more uncertainty with the models regarding several potential low pressure systems across the region. Even though there is uncertainty with the individual details of this time frame, with the models only expected to begin reaching a closer consensus once this time frame reaches the shorter range, but when looking at the overall pattern at that time, there is a greater chance that the area may see rain around Thursday/Friday next week, along with mild temperatures, potentially getting close to the 80 degree mark. Stay tuned for more information on the end of next week.

Wednesday, September 14, 2011

Sept 14, 2011: October-Like Weekend Ahead

The surge of warmth brought above average temperatures across the area for the last few days, but with a cold front approaching, this warmth will end tomorrow with a line of showers and thunderstorms moving through during the afternoon hours across the area. Behind this front, temperatures will quickly drop along with gusty winds, gusting up to 30 mph across most of the area on Thursday evening, but the main story will be the temperatures, which will drop into the 40s for lows and the 60s for highs on Friday and the weekend, around the average temperatures during October. A stalled high pressure will keep these conditions in place, with chilly and dry conditions lasting into next week.


Tomorrow's Outlook:

With the cold front moving through, tomorrow will bring colder temperatures. Combined with colder temperatures aloft, rain, and cloudy cover, temperatures will bring high temperatures into the upper 60s to lower 70s inland, mid 70s in the immediate NYC area, and the lower to mid 70s across Long Island and southern Connecticut. The rain is expected to move into the area around 11 AM-2 PM from NYC and further west, and between 2 PM-6 PM east of NYC. The rain will end by the evening hours across the area, with at 0.1 to 1/4 inch of rain east of NYC and 1/4 to 1/2 inch from NYC and further west.

Due to the timing of the rain, high temperatures tomorrow will peak earlier than usual, around 12 PM. Once the rain moves in, temperatures will drop slightly, and once the rain ends as the cold front moves through, temperatures will quickly drop in the late afternoon with gusty NW winds, gusting up to 30 mph across the area. By 8 PM, the majority of the area except for Long Island will have dropped below the 60 degree mark. There is some uncertainty with tomorrow's high temperatures, as the temperatures depend on when the rain moves into the area. Should the rain move in later than expected, temperatures may reach 80 degrees in parts of the immediate NYC area. In addition, it is possible that temperatures in NW NJ/SE NY could be colder than shown on the graphic above.

Friday - Next Week: Chilly, Dry

Behind the cold front, a much colder air mass will move into the region. Cloud cover will clear on Thursday night as winds steadily decrease throughout the overnight hours. Low temperatures will drop into the upper 30s to lower 40s in NW NJ/SE NY, mid to upper 40s in NE NJ/southern CT/Long Island, and the lower 50s in NYC. Friday will bring colder high temperatures, peaking in the lower to mid 60s inland and the mid to upper 60s across the rest of the area. Temperatures will steadily warm up through the weekend into early next week as a high pressure will remain stuck over the area, keeping dry conditions and mostly to partly sunny skies in place. By the middle of next week, temperatures will reach the lower to upper 70s across the area, and rain chances will return by mid-late next week.

Tuesday, September 13, 2011

Sept 13, 2011: Warmth Ends On Thursday

The NYC area observed partly cloudy skies today, with temperatures once again above average, peaking in the lower 80s inland, lower to mid 80s in the immediate NYC area, and in the upper 70s to lower 80s in Long Island and southern Connecticut.

The latest regional radar shows that there are thunderstorms in far northern and western NY associated with a cold front. This cold front will approach the area, but will fail to cross the area tomorrow. Instead, another low pressure on Thursday will push this front through the area with showers and thunderstorms. Behind this front, a dry and chilly pattern will develop across the region, as temperatures will drop into the 40s for overnight lows with dry conditions lasting through next week due to a high pressure which is expected to be stuck over the Northeast.


Tomorrow's Outlook:

As previously mentioned, a cold front moving towards the region will fail to move through the area, and will instead remain stationary near the central Northeast, to the west of the area. This will keep a SW wind with above average temperatures in place for the area once again. Temperatures will be warmer than they were today, reaching the lower to potentially mid 80s inland, mid 80s in the immediate NYC area, and the upper 70s to mid 80s in Long Island and southern Connecticut. Parts of NE NJ may reach the upper 80s.


Thursday: Cold Front Brings Rain, Thunderstorms

An update early this evening mentioned that the latest models have trended stronger with a low pressure in southern Canada, which resulted in a stronger front moving through the region. This change in the expectation, combined with the models trending slower with the timing of the front, increases the risk of rain and thunderstorms during the day on Thursday. The NAM model is the most bullish with this potential, showing nearly 1 inch of rain in NYC, and although such amounts are possible in a few areas west of NYC, widespread heavy rain is not expected with this event at this time. The NAM may still be having some issues handling this event as it shows a very strong temperature gradient with this front, with some places dropping over 20 degrees in in just 1-2 hours, which is most likely too extreme. The front will bring light to moderate rain and thunderstorms throughout the day on Thursday, focusing on the second half of the day. By the time that the rain ends on Thursday evening, at least 1/4 to 3/4 inch of rain is expected, with locally higher amounts possible. Stay tuned for more information on Thursday's rain event with tomorrow's update.


Friday - Next Week: Dry And Chilly

Behind Thursday's cold front, a strong high pressure will begin to move towards the region. A relatively tight pressure gradient is expected behind the front, which will produce windy conditions on Thursday night into Friday, with winds potentially gusting up to 30 mph on Thursday evening once the front moves through. Clearing skies are expected later into the overnight hours, and as a strong trough begins to move into the region, temperatures will quickly cool down, dropping into the lower 40s in NW NJ/SE NY, mid to upper 40s in the immediate north/west suburbs of NYC and southern CT, mid 40s to lower 50s in Long Island, and the lower 50s in NYC. While no frost is expected in the area, parts of the interior Northeast will experience the first frost of this fall.

Friday will bring mostly sunny skies as the high pressure moves into the Northeast, with temperatures colder than those of Thursday, only rising into the lower to mid 60s in NW NJ/SE NY and the mid to upper 60s across the rest of the area. With mostly clear skies on Friday night, low temperatures similar to those of Thursday night are expected. The cold air mass will begin to slightly weaken on Saturday, with temperatures slightly rising, peaking in the mid 60s inland and the upper 60s across the rest of the area.

From Sunday through about the middle of next week, the latest models are showing the strong high pressure settling over the region as a low pressure develops well offshore, keeping the area under dry conditions and chilly temperatures, in the upper 60s to mid 70s. Only one model, the DGEX, takes this low pressure and moves it right up the coast with heavy rain, and the DGEX typically isn't reliable in its longer range. At this time, the next chance of rain appears to be towards the middle of next week, but there is uncertainty with the models regarding what happens with the high pressure by that time. Stay tuned for more information for next week's outlook.