Thursday, September 30, 2010

Sept 30 Night: Final Storm Update

10:00 PM: As the low pressure is now moving inland into North Carolina, from the radar observations, it is becoming apparent that less rain than the original forecast will fall for the area.

From my post earlier this afternoon, it appeared that the forecast could bust, as despite the models still indicating 3-5 inches of rain for the area, the observations suggested otherwise. The latest model trends and the observations continue to support my thoughts that rain totals could end up significantly lower than the original forecast for the storm due to an unexpected turn in the storm set up.


What Is Going Wrong?

I'll have more on what went wrong with the forecast with a post tomorrow about this storm and reviewing what happened, but I'll give an explanation of what went wrong so far and could go wrong tonight.

The first low pressure ended up moving further inland than expected, which combined with a sharper cut off than some models expected, led to a dry yet windy day for the area. The second low pressure was supposed to start turning north then NNE, moving just off the coast and slightly east of NYC, as the cold front from the first storm would push the storm further east, however that has failed to happen so far, and as with the first storm, the second storm is currently pushing more inland than expected, and is still moving NNW. By 8 PM, the models from earlier today already had the storm moving NNE, with heavy rain starting to fall in NYC, however it is already 10 PM and this has failed to happen.

The storm will continue to move NNW then north, and will eventually be forced to turn NNE due to the cold front, which will move east, bringing heavy rain to at least parts of the area, however most of the heavy rain will stay to the north and west of New York City, as the low pressure moves just west of New York City. Due to this, however, strong winds can be expected in Long Island tonight, with gusts up to 60 mph possible, with lighter but still strong winds for the immediate NYC area. Only the interior parts of the area (NW NJ, Orange County in NY) will see the very heavy rain.

Rain Forecast:

With the above said, I posted my rain forecast to the left. The right end of the dark green zone could be a little east of my forecast, but for now these are the main boundaries I am using.

For the dark green zone, expect a steady heavy rain for most of tonight into tomorrow morning, with a total of 3 to 5 inches of rain expected. Rainfall amounts could be locally higher in heavy rain bands.

In the green zone, expect 1 to 3 inches of rain, with at least 1 to 1.5" for NYC, if not a little lower in the drier case scenario. By the time that the storm is nearing NYC, the rain will start to move more eastward, but likely in the form of a moving line of heavy rain, not a stalled heavy rain line that the central Mid Atlantic has seen all day and NW NJ/eastern PA will likely see tonight.

In the light green area, expect generally less than 1 inch of rain. The rain will be in the form of moderate rain moving NE, and while the rain will be relatively light, strong wind gusts will be the main concern, with gusts up to 60 mph possible.

Note On The Forecast: The above is my current thinking, and is based on my thinking and the RUC short term model, that has been catching on to this trend. Rain totals can still end up slightly different than my forecast, especially if another unexpected turn happens, but for now this is my thinking.

Before the storm, I said that this could be a damaging storm and cause significant impact on the area, and while that did not happen yet, because of the storm being further west it has had a significant impact on a line from eastern Virginia through eastern Maryland and Pennsylvania. In that area, between 8 to as much as 12 inches of rain fell so far, and rain is still coming down. These places are likely to break records for the most amount of rain in 24 hours, and there is significant flooding in those areas. Had the storm not been this far west, we could have been dealing with the same effects in the NYC area.

I will post a summary of this storm tomorrow, with a brief forecast for the next few days, but the next full update will be posted on Saturday.

Sept 30 Evening: Lowered Rain Totals?

6:40 PM: It is currently 6 PM and most of the area is still dry. The winds have been increasing a little, but are still a little weaker than they were expected to be. Moderate rain is currently falling in eastern Pennsylvania in between the two areas of rain, with more heavy rain to move into those areas tonight. From eastern Virginia to eastern MD and eastern/central PA, the worst of the storm will be felt, as once the storm is over, as much as 15 inches of rain could fall in those places.

For the area, however, it is starting to appear that the heaviest rain may never get into the area as the models have been suggesting. The latest short term RUC model runs have been trending west with each run, now barely bringing 6 hours of moderate to heavy rain in NYC and only light rain for Long Island, and keeping the area dry until 2 AM. The radar supports this, as the secondary low pressure is moving further inland than thought at first.

At first, the models had the low pressure moving just offshore, being why excessive rain totals were shown for the area, but the low pressure now appears to track inland, moving just near NYC, putting the heaviest rainfall once again where it has been all day long, from eastern VA through eastern PA, with moderate-heavy rain in NYC but amounts generally up to 2-4 inches, not the 4-7 inches of rain suggested at first. It is possible that the rain ends up a little further east and NYC sees 3-5 inches, or it trends west and NYC sees only 1-2 inches, however at this time I am going in between, currently expecting 3 to 5 inches inland, 1.5 to 3.5 inches for NYC, and 1/2 to 1.5 inches for Long Island/S CT, with the lower end of that range being the RUC's forecast totals. Stay tuned to another update around 10 PM to see whether there is any change in the thinking for the storm, especially if there is any downward or upward adjustments to the rain totals.

With the low pressure tracking near NYC, the potential for strong winds tonight is also increasing, mainly for Long Island. Had the low pressure followed the original forecast, it would've brought more rain and less wind, but with a further west track, less rain and more wind are in the forecast.

Sept 30 Noon: Worst Has Yet To Come

3:14 PM: This morning, very heavy rain and thunderstorms fell in parts of the area, bringing up to 1.25 inch in the immediate NYC area, but most of Long Island and parts of southern Connecticut got less than 1/4 inch. As the storm ended up today slightly west of the forecast, and with the models late last night having introduced a dry slot for NYC, the area has stayed mainly dry for the last 6 hours as all of the rain is to the west, with parts of Virginia and Maryland soaked with nearly 10 inches of rain. As more will come for these areas, those places could easily exceed 10 inches of rain.

Don't be mistaken by this windy and dry afternoon, however; the worst has yet to come. Yesterday, I mentioned that a second round could bring the heaviest rain to NYC/Long Island, which is now the expected scenario. Rain will start affecting the area from west to east later today, along with increasing winds, but New York City likely won't see much more than light rain until 10 PM to 12 AM.

Afterwards, the low pressure associated with Nicole's remnants will move up the coast, and according to the latest models, will pass slightly east of NYC, leading to very heavy rain affecting parts of Long Island, NYC and all of New Jersey. If this scenario verifies, there is the potential for 4 to 7 inches of rain to affect the areas mentioned above late tonight, with strong wind gusts up to 60 mph possible, especially in Long Island. The NAM and GFS are showing much lighter amounts, however as we have seen in Maryland and Virginia, more than several inches of rain can fall in a short period of time, especially with a lot of moisture, as we are currently seeing.

Stay tuned for another update later tonight to see whether anything has changed or if the area is still expected to see heavy rain late tonight.

Wednesday, September 29, 2010

Sept 29: Final Storm Forecast

Warnings:

There are currently two alerts in effect, a Heavy Rain Warning, and a High Wind Watch. For more details, read below, or read the appropriate alerts in the "Weather Alerts" page.

The 5-Day Forecast was not updated tonight.


Final Forecast:

The models are now coming into a consensus that the heavier rain amounts will likely affect the area. As a result, I have increased the forecast rain totals from yesterday's forecast and kept them the same as those from earlier this afternoon.

Tropical Storm Nicole has dissipated, but a low pressure related to Nicole's moisture will move up the East Coast, bringing heavy rain tomorrow. The heaviest rain from this round will likely fall towards western New Jersey and eastern Pennsylvania, with 3 to 5 inches possible during the day. The immediate NYC area will likely see 2 to 4 inches, with Long Island/S CT seeing 1-2 inches.

By Thursday night, as the first low pressure moves into New England, another low pressure could approach the area, bringing another round of heavy rain, but this time focusing further east than the first round of heavy rain, moving through the immediate NYC area and Long Island/S CT, bringing 2-3 inches of rain for those areas.

The rain will end by Friday morning. By the time that the storm ends, 4 to 7 inches of rain are possible for the interior and the immediate NYC area, with 3 to 5 inches of rain for Long Island/S CT. I put up a rain map above, with the model consensus and my thoughts put into it. The NAM/GFS/SREF are west of the model consensus, and while I did take them into consideration, I do not think the rain will be as far west as they show it to be. While I include the area in the 5+ inch area, not the entire 5+ inch area will see 5+ inches, but it is meant to show where the best chance of seeing over 5 inches of rain is.

Despite this, there is still some uncertainty, and it is possible that the heavy rain could end up slightly west of my forecast.

Winds: Strong wind gusts are also expected with this storm. As the eastern side of the storm typically brings strong winds, I placed Long Island/S CT and the immediate NYC area in a High Wind Watch. Sustained winds between 30 and 40 mph, with gusts as high as 55-60 mph are likely with this storm, which could cause damage along with the flooding. Some severe weather could also be possible with this, as SPC has placed the area under a slight risk of severe weather.

Overall Summary:

This will likely be the strongest storm to affect the area since the March nor'easters. Heavy rain with 4 to 8 inches and flooding will affect a large part of the Mid Atlantic and Northeast, with strong wind gusts up to 60 mph in the eastern parts of the storm also causing damage. This is not a storm to take lightly, and while the scenario could still change around a little, this storm could have a significant impact on the area.

Updates will be posted tomorrow afternoon while the storm is ongoing.

Sept 29 Noon: Thoughts On TS Nicole

***This is not the final forecast for Nicole yet. This post is meant to represent my current thoughts and planning for my final forecast, which will be posted by 7 PM tonight.***


Today started out as a mainly sunny day, but quickly turned mainly cloudy ahead of a storm that will bring the heaviest rain to the area since the March nor'easters. In the radar image to the left, rain is already starting to move up the Mid Atlantic, which could start affecting the area by tonight, however the heaviest has yet to come.

Tropical Depression 16 has been named Nicole earlier today, the 13th named storm of this hurricane season. Nicole's center is currently between Bermuda and the Bahamas. For tomorrow, it appears that Nicole could not be the storm to affect the area, but rather a low pressure forming ahead of Nicole will do so, tracking just west of NYC.

Potential Rain/Wind Totals:

The solution mentioned above, supported by the recent models, will bring heavy rain for the area, with 1-2 inches in Long Island/S CT (with lesser amounts further east), 2-4 inches for the immediate NYC area, and 3-5 inches inland during the day on Thursday. If I was to go by the latest models, then Nicole's center would come through on Thursday night, bringing 1-2 inches inland, 2-3 inches for the immediate NYC area, and 2-4 inches for Long Island/S CT. This would lead to a total of 4-7 inches inland, 4-7 inches for NYC, and 3-6 inches for Long Island/S CT. Note that these rainfall amounts are only according to the latest solutions, and could change when I post my final forecast later tonight.

What I posted above was mainly based on the latest models, which trended east of yesterday's runs. Every model now shows most of the area with over 3 inches of rain, with the GGEM showing 7-8 inches of rain in NYC. The models are also showing strong winds for the central/eastern parts of the area, with sustained winds between 30-45 mph and gusts up to 50-60 mph possible. It is still possible, however, that we see a different outcome, as there is still some uncertainty. After seeing today's late afternoon model runs, which will come out in the next 2-3 hours, and putting in some of my thoughts about which scenario could take place, I will post the final forecast for Nicole by 7 PM.

Tuesday, September 28, 2010

Sept 28: Changes In Forecast For TD16

Note: today only has a brief update, and the pages were not updated. Expect a full update tomorrow, with the final forecast for Tropical Depression 16/potential Nicole.


Today's Storm Review: Why Did It Fail?



Unlike what the models have been consistently showing, and the radar appearance of the storm before the rain fell apart last night, the rain event that affected the area has busted too low, with some places seeing totals as low as 1/4 inch, when it appeared for days that this would likely be a solid 1/2+ inch event. The heaviest rain totals ended up in western Long Island, however these amounts aren't too high, and are generally below 2 inches.

The small severe weather risk that was also in effect for today did not verify, as the parameters and the radar appearance did not support widespread severe weather activity for today, being why I kept the Severe Weather Alert in place instead of a watch, indicating a less than 70% chance of severe weather. There were some locally heavy storms, but they were not severe.

Forecasts For Tropical Depression 16: Too Far West?



Yesterday's forecasts mentioned that the models have trended west with the forecast for 96L, which is now Tropical Depression 16, however today's models have trended much further west, now bringing the heavy rain to central VA into central Pennsylvania, where 3-6 inches of rain are likely, but have decreased rainfall amounts in the area to barely 1 to 2.5 inches. Despite this, the forecast winds have increased, with sustained winds up to 40-50 mph and gusts up to 60 mph now possible for Long Island, S CT and potentially the immediate NYC area if the current scenario was to verify.



Despite the impact timing only being 2 days from now, there is still significant uncertainty, which could continue until the last minute. Tropical Depression 16 is currently disorganized, and may not be able to get its act together into a tropical storm before becoming extra-tropical, and at this time, its pressure of 997 mb is much lower than that of a typical Tropical Depression. While it is likely to intensify as it becomes extra-tropical and moves up the East Coast, we can still end up with a different scenario.

The track forecast is currently the most uncertain. The models today have significantly trended west from yesterday's models, however TD16 has yet to have an organized center, and according to NHC's 8 PM update, TD16's center shifted a little to the east, which may have an impact on the overall track. The further west it goes, less rain and stronger winds can be expected for the area, and the further east it goes, more rain and less wind can be expected.

Stay tuned for more details with tomorrow's full update, including final maps, and updated alerts and 5-Day Forecasts.

Monday, September 27, 2010

Sept 27: Tropical Storm Conditions Possible Thursday

Notes:

- There are currently three alerts in effect, a Rain Warning and a Severe Thunderstorm Alert for the entire area tomorrow, and a Heavy Rain Watch for Thursday for the potential tropical/extra-tropical cyclone that will likely affect the East Coast. If this will still be tropical when affecting the area, a tropical storm watch may be needed.

- The 5-Day Forecast has been updated tonight. For those who find the discussion in the main page too complex to understand, you can read the alerts currently active for more details on the potential scenarios.

- The poll for how much rain will fall until tomorrow has been closed, with a total of 8 votes. There are 3 votes for 1/2-1" and 1-2" each, 1 vote for 2-4", and 1 vote for 4+". A new poll has been opened, about the potential effects of 96L (potential Nicole) on the area. Vote your thoughts on the poll, which ends on Wednesday.

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What is going to be a very busy week started today with widespread light to moderate rain moving into the area. Rain totals so far are generally between 1/2 and 1 inch, with heavy rain to move into the area tonight and tomorrow, bringing another 1 to 2 inches of rain.

While Wednesday will be drier, relief will only be short as a tropical storm will likely move up the East Coast, bringing an additional several inches of rain and strong winds to the area, only to be followed by a significant cool spell with frosts and freeze for the interior.

Tonight And Tomorrow's Outlook:

While the area is currently dry, rain is expected to move into the area once again late tonight, and will be locally heavy. This locally heavy rain will generally continue until tomorrow, when thunderstorms, locally strong with gusty winds, are expected. The rain will then end by late tomorrow afternoon. Temperatures tonight will be steady, if not rise due to the warm air mass entering the area, then peak in the lower to upper 70s tomorrow.

By the time that the storm is over, an additional 1 to 2 inches of rain are expected for the area, putting the storm total as much as 3 inches in some places.

Wednesday - Friday: Tropical Storm Moves Up The East Coast


As I mentioned yesterday, the models are now trending towards a solution where a tropical system forming in the northern Caribbean and moving towards Florida affects the entire East Coast directly. This solution is now much more consistent, with a lot of models showing a direct hit over New York City, somewhere between Tracks 1 and 2 from yesterday. With the consistency with the models, and the expected pattern, that is the scenario I decided to use for today's forecast.




With that said, if this solution verifies, this could be a potentially damaging storm for the East Coast. Heavy rainfall with a widespread 2-4 inches and amounts locally as high as 5-6 inches could affect the coast from North Carolina through New Jersey into New England, with tropical storm force winds for NYC and strong TS force winds for eastern New England and Long Island possible if the GFS solutions verify, as these places would be east of the storm track, where the wind is usually the bigger threat rather than rain.

For now, in my 5-Day Forecast, I included heavy rain and 2-4 inches during Thursday. The storm is likely to move in during Wednesday night, and move out late Thursday night. It is still possible that the storm goes out to sea like the ECMWF is showing, however this possibility is becoming less likely. Stay tuned for more details as coverage on this potential tropical cyclone and how it may affect the area continues over the next few days.

Saturday - Monday: Significant Cool Down, First Freeze For Interior?

After potential Nicole moves out of the area, a strong trough will move into the entire region, bringing below to well below average temperatures. Saturday will only be a little chilly with highs in the lower to upper 60s, but Sunday really starts to cool down as 850 mb temperatures approach zero degrees celsius. High temperatures on Sunday and Monday are currently likely to be in the mid 50s inland and upper 50s for the rest of the area, however these are still subject to change.

Overnight lows, however, will be very chilly, with the GFS and DGEX suggesting lower to mid 30s inland, mid 30s to lower 40s for the immediate NYC Suburbs/southern Connecticut, and mid to upper 40s for NYC. While they could slightly change around, the idea is that widespread frost is possible for the area on Sunday night, with freeze even possible for the interior. Stay tuned for more details on this time frame and how cold it could get.

Sunday, September 26, 2010

Sept 26: Tropical Cyclone Could Move Up East Coast

Storm Outlook For Monday And Tuesday:

Tomorrow will be a cloudy day with rain moving into the area. High temperatures will be in the mid 60s inland and in the upper 60s for NYC, with mid-upper 60s in Long Island/S CT due to the cloud cover and rain in place, which is slightly cooler than the model consensus for tomorrow's highs.

Light to moderate rain will begin to enter the area tomorrow afternoon, and will become moderate to locally heavy during the overnight hours. By Tuesday, a line of heavy rain and thunderstorms will likely move through, and with a south wind and highs in the 70s, as well as some CAPE/LI and strong shear, some storms could be strong or severe, with heavy rain and strong wind gusts the main threat.

By the time that the storm ends on Tuesday night, 1 to 2 inches of rain are expected for the area, with as much as 3 inches in isolated spots, mainly in the western parts of the area.

Wednesday And Thursday: Mild, But Mainly Cloudy

During Wednesday, the cold front will likely stall to our east, providing mainly cloudy skies, an isolated shower or two, and mild temperatures in the lower to mid 70s.

Thursday Night - Friday: Tropical Cyclone?

From what I mentioned two days ago, the models are now consistent in developing a low pressure in the Caribbean into a tropical cyclone, which would be named Nicole. Looking at the possible scenarios (posted in the map to the left), Nicole would form on Tuesday, move towards Florida by Wednesday, then either move up the East Coast or get pushed out to sea. If it affects the area, it would be on Friday.

There is question on if and when it develops, as it is currently relatively disorganized, and even though development isn't expected for another 48 hours, as we've seen with Matthew, it could take longer for it to organize. And if it takes too long to do so, it would easily be pushed out to sea by the trough. But if it follows the current model scenario, track #2, the cold front would likely be slower in moving into the Northeast, allowing potential Nicole to hug the East Coast before being pushed out to sea. For now, I used a mixture of Tracks #2 and 3 for my 5-Day Forecast, but this is relatively low confidence and is subject to change.

Stay tuned for more details on this potential tropical cyclone, and if it forms, how it may affect the area.

Longer Range: Tomorrow's update will also focus more on the longer range, including Saturday-Monday, when we could see a significant cool spell with widespread frost potentially affecting the area.

Saturday, September 25, 2010

Sept 25: Significant Cool Spell To Start October?

Today was the last of the unusually warm days as the cold front started moving through, however a last minute trend on the models this morning indicated that today would be warmer than expected, which was the case, as a few parts of the area reached the 90 degree mark once again. Tomorrow will be much cooler for the area, with highs back into the 60s and lower 70s, with more rain for Tuesday and a weak warm up afterwards, only to be followed by what could be the strongest cool spell so far this fall.

Outlook For Tomorrow And Monday:

Tomorrow will be partly sunny with a NNE wind expected. High temperatures will rise into the mid to upper 60s inland and upper 60s to lower 70s for the rest of the area. The NAM was too cold at first, showing highs in the upper 50s to lower 60s, but as expected, it has trended warmer, and now shows mid-upper 60s for NYC, though this is still likely a little too cold.

The NAM is now doing the same story for Monday, showing highs only in the upper 50s to lower 60s, however this is likely too cold once again, and I am leaning towards the warmer models showing highs in the upper 60s to lower 70s across most of the area. Cloudy skies and showers are expected for Monday.

Tuesday: Heavy Rain Returns To The Area

A storm will start to bring rain to the area on Monday night as the low pressure moves up the East Coast while inland, just west of the Appalachians. This will bring mild temperatures for Monday night with light to moderate rain, and as the cold front moves through, a line of heavy rain and thunderstorms will likely move through for Tuesday, bringing the potential for up to 2 inches of rain locally, as well as some strong-severe storms and gusty winds. For now, I have not issued a Severe Thunderstorm Alert, however I am keeping an eye on this scenario in case severe weather becomes more likely.

As the heaviest rain will likely fall in the western parts of the area, I upgraded the immediate NYC area and the interior (NW NJ, Orange County in NY) to a Rain Warning, indicating a greater than 70% chance of over 1 inch of rain, but I kept Long Island/S CT with a Rain Watch, as it is possible that the heaviest rain stays too far west for these areas. Note that there is still uncertainty with the exact heavy rain placement, and the forecast for rain totals could slightly change in the next day or so. Stay tuned for more details on this storm.

**For those who do not know where to find the alerts, they can be seen in the "Weather Alerts" page, the link is in the top of the website.**

Wednesday - Friday Afternoon: Mild, But Mainly Cloudy

The cold front will likely stall to our east on Wednesday, keeping mostly cloudy skies in place with an isolated shower or two possible on Wednesday and Thursday. For now, I have partly/mostly cloudy skies in the forecast, but note that I could include more cloud cover and a shower chance with tomorrow's update.

High temperatures will likely be in the lower to upper 70s across the area for Wednesday and Thursday, with Friday likely slightly cooler as a trough approaches the area.

Friday - Sunday: Significant Cool Spell Possible

The models are now becoming more consistent on keeping potential Nicole out to sea, with a strong trough moving into the area. I am currently thinking that this potential cyclone is not too likely to affect the area, however this time frame is still uncertain and I am keeping an eye on it in case the expected scenario changes.

If I were to follow the current scenario, a strong trough would move into the area during Friday night, bringing below average lows. Saturday night would be the coldest night, with lows in the 30s to lower 40s for most of the area except for NYC, with high temperatures in the mid 50s to mid 60s possible across the area. As I mentioned above, this is still uncertain, and can still change. Stay tuned for more details on this time frame.

Friday, September 24, 2010

Sept 24: Rain, Storms On Tuesday

Notes:

- A Rain Watch remains in effect for the area. It is possible that with tomorrow's update, this watch is upgraded to a warning, and a Severe Thunderstorm Alert may also be issued. In addition, the poll for how much rain could fall during this time frame is still open, please vote your thoughts in the poll.

- The 5-Day Forecast page was updated tonight.

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This morning brought foggy conditions to a lot of the area, however the fog took much longer to burn off than expected, leading to the high temperatures being much lower than the forecast, only reaching the lower to mid 80s in the immediate NYC area. The Mid Atlantic, however, was able to quickly warm up, and a lot of places reached the upper 90s. Tomorrow will be mild again as the cold front moves through, with a much cooler Sunday, but afterwards the next potential for rain returns on Tuesday, and severe thunderstorms may return again.

Tomorrow's Outlook:

Tomorrow will be a partly cloudy day with a SW wind expected. High temperatures will reach the lower 80s inland, mid to potentially upper 80s in the immediate NYC area, and lower 80s for Long Island/S CT. The cold front will move through, however it will be a dry frontal passage, with no rain expected.

Sunday And Monday: Much Cooler

As the cold front moves through, Sunday will bring much cooler temperatures. There is a split between the models at this time, the NAM is expecting highs in the upper 50s-lower 60s, the GFS in the mid 60s-lower 70s, and the GGEM is slightly warmer than the GFS. At this time, I am thinking that the NAM is too cold for both Sunday and Monday, but despite this, for now I am leaning a little closer to the NAM than the GFS, with highs in the mid 60s inland and mid-upper 60s for NYC, though this is still subject to change.

Monday will be slightly warmer but still chilly, with highs in the mid 60s to lower 70s across the area, but cloud cover will increase ahead of the next storm.

Tuesday Storm: Heavy Rain, Severe Weather?

Rain will likely start falling across the area on Monday night, and the low pressure slowly moves north to NNE from the Southeast into Pennsylvania and towards southern Canada, its cold front will approach, bringing a line of heavy rain and thunderstorms for Tuesday. This is a very moist air mass, with precipitable water values near 2 inches, which will support locally heavy rainfall, bringing the storm total likely into the range of 1-3 inches, though it could end up higher. I am currently considering upgrading the Rain Watch to a warning, however I will wait until tomorrow before deciding whether to do so or not.

With the cold front, however, comes the potential for severe weather. The GFS is showing shear up to 50 knots, with supportive CAPE/LI, and if the timing and the low position work out, severe thunderstorms could be possible along this storm line on Tuesday, with the main threat being gusty winds. While this only recently started showing up, I am waiting to see tomorrow's runs before deciding whether this is still likely to happen or not, I mentioned gusty winds and heavy rainfall for Tuesday in my 5-Day Forecast. Stay tuned for more details on this potential.

Longer Range: Significant Cool Spell Possible Starting Friday

As I mentioned yesterday, a strong trough could approach the East Coast by Friday, affecting the area on Saturday and Sunday. If a tropical cyclone was to not affect the area and the trough would move into the area, as the latest GFS/ECMWF/DGEX runs show, this would bring well below average temperatures, with highs in the 50s and lows in the 30s, however it is also possible that the trough isn't as strong as the models are showing, or a hurricane could move up the East Coast and interact with the trough to form a strong storm (more on that below in the Tropics section). Stay tuned for more details on this time frame and what it may bring to the area.


Tropics: Matthew To Weaken, But Another Storm To Form?


Tropical Storm Matthew made landfall over Nicaragua earlier today as a 50 mph tropical storm, and while it will likely continue to weaken from this point, and will eventually become a tropical depression over land, the models are now hinting that the storm to affect the United States will be a separate storm forming close to Matthew.

The models are currently showing a tropical cyclone forming near Jamaica, intensifying while moving through Cuba, then affecting Florida. Afterwards, solutions vary, ranging from a Gulf of Mexico solution, to an out to sea solution, or moving up the East Coast, directly affecting the NYC area.

It should be noted, however, that if it does move up the East Coast, following the model solutions earlier today that showed this, it would be an extra-tropical cyclone interacting with a strong trough, leading to a strong extra-tropical storm with cold, heavy rain possible for NYC and even snow for parts of the Northeast. There is a lot of uncertainty on this time frame at this time, stay tuned for more details on this over the next few days and how this may affect the area.

Elsewhere in the tropics: Julia's remnants are no longer labeled for redevelopment by the National Hurricane Center, and are not expected to redevelop. Lisa, like several other storms this season, gave a quick round of unexpected rapid intensification, and is now a hurricane, the 7th one this season so far. Lisa could intensify some more, but will then likely start to weaken. Lisa is currently not a threat to land.

Thursday, September 23, 2010

Sept 23: Heavy Rain Possible Next Week

Notes:

- NYC Area Weather currently has two advisories in effect: Heat Alert for NYC tomorrow, and a Rain Watch for the entire area between Monday and Wednesday.

- The 5-Day Forecast has been updated for the area.

- A new poll has been added in the top right side of the blog, under the radar, about the potential rainfall amounts for the arae between Monday and Wednesday. Please vote your thoughts in the poll, which will close on Monday.

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After yesterday's storms moved through, causing wind damage across parts of the area, today brought much nicer conditions. Temperatures failed to reach the forecast high temperatures as the position of the stalled front provided a SE wind instead of a SW wind, which caused cooler temperatures, however with a SSW wind returning, tomorrow is going to be a hot and humid day, likely the last of those we'll see until next summer.

While the cold frontal passage on Saturday will bring much cooler temperatures, with highs dropping into the mid 60s to lower 70s, it will be a dry cold front, but the dry conditions will not last for long, as there is the potential for a significant rainstorm in the middle of next week, and Tropical Storm Matthew is also being kept an eye on in case it goes up the East Coast as some models have been suggesting.

Tomorrow's Outlook:

Tomorrow will be a summer-like day, with a very warm air mass and a SSW wind. High temperatures will reach the mid to upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and due to an onshore wind, Long Island and S CT will reach the upper 70s to lower 80s, with a few mid 80s in western Long Island.

There will be a sharp temperature contrast across the Northeast. Virginia and Washington DC will see high temperatures in the upper 90s, to near 90 in NYC, to the upper 70s to lower 80s from northern New York into central New England, with a chilly heavy rain and 50s in Maine.


Weekend Outlook: Hot Start, Cold Finish


With the cold front approaching, Friday night will be rather mild, with lows in the lower to potentially mid 60s inland, upper 60s in S CT and the N/W suburbs of NYC, and in the lower 70s for NYC and parts of Long Island. Increasing cloud cover is also expected.

The cold front will move through on Saturday, however it will only be a dry frontal passage, with an isolated shower or thunderstorm possible but nothing like what we saw yesterday. The cold front, however, will be slow enough to allow for a SW wind during Friday afternoon just before it moves out, leading to high temperatures in the lower 80s inland, mid to locally upper 80s in NYC, and lower 80s in Long Island/S CT. Saturday night will be chilly, with lows ranging from the upper 40s inland to the upper 50s in NYC.

Sunday will be a rather chilly day, with partly sunny skies and a north wind expected. High temperatures will be in the mid to locally upper 60s inland, upper 60s to locally lower 70s for the immediate NYC area, and in thepper 60s to lower 70s for Long Island/S CT.


Monday-Wednesday: Heavy Rain Potential


By Monday, temperatures will be slightly warmer than those of Sunday, however there will be increasing cloud cover ahead of a storm. A cut off low pressure is expected to approach Tennessee and slowly move toawrds the area, bringing a surge of Gulf of Mexico moisture into the eastern United States. There is still a lot of uncertainty on the smaller details, such as the exact track of the low pressure, how much rain falls and who gets how much rain, but it is starting to become clear that a potentially significant rain event may be unfolding for early-mid next week, and in the wetter scenario, several inches of rain may affect the area. I have issued a Rain Watch for this storm, indicating a 40-70% chance of more than 1 inch of rain (more details in the "Weather Alerts" page). Stay tuned for more details on this storm over the next few days.


Longer Range: Significant Cool Spell For Early October?


The models have been consistent lately in showing a large trough dropping into the Mid Atlantic and Northeast between October 1 and 3, bringing the coldest temperatures yet this fall. There is uncertainty on this time period, especially if Matthew ends up affecting the East Coast, but this potential will be watched.


Tropics Update: Lisa Weakening, Matthew Intensifying


Other Areas In Tropics:

Tropical Storm Lisa, having weakened to a tropical depression earlier today, is back up to a tropical storm, but with an unfavorable environment, will likely weaken to a tropical depression again soon. All models show Lisa dissipating in the next few days, and Lisa is not a threat to land. Julia's remnants, meanwhile, are getting more organized, however at this time Julia is unlikely to regenerate.

Tropical Storm Matthew To Affect Honduras, Mexico

The tropical threat I was talking about over the last few days has developed into Tropical Storm Matthew today. Matthew, however, will not become a major hurricane at least as of now, as it formed later and is moving faster than I expected, and is slow to intensify, but will likely be a strong tropical storm when it reaches Honduras. Despite not being a hurricane yet, Matthew will produce flooding and strong winds for that region, potentially causing significant damage. Matthew will then slow down, and will likely stall close to the Yucatan Peninsula.

What happens afterwards is still a question. One set of models take Matthew northeast from there, moving near Cuba and Florida and potentially going up the East Coast, the other models take Matthew north into the Gulf of Mexico, and some models take it due WNW through the Yucatan and into the western Gulf of Mexico, however this solution is unlikely at this time. Stay tuned for more details on Matthew over the next few days, along with discussions and forecast track/intensity maps.

Wednesday, September 22, 2010

Sept 22 Noon: Severe Storms

***NYC Area Weather has issued a Severe Thunderstorm Watch for the entire area. While I may not update through the whole time, please refer to the National Weather Service for the latest alerts and warnings.***

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8:45 PM: There are currently two strong/severe thunderstorms. The first storm is near Bridgeport, CT, moving ENE, and is capable of producing gusty winds, small hail, and heavy rain. The second and bigger storm is in Staten Island, and is going to shortly affect Brooklyn, Queens, and JFK/Long Beach. SW Long Island will be affected by this storm, which is capable of producing strong wind gusts, small to moderate hail, and heavy rain.



8:10 PM: A severe thunderstorm just moved through Bergen county, and is now entering Westchester County. Expect gusty winds, small hail, and heavy rain with this storm. This storm may clip SW Connecticut, including Stamford, before moving offshore. A strong thunderstorm is forming to its north, just north of Tarrytown, NY, and will move towards Bridgeport, CT.

A very intense severe thunderstorm capable of producing damaging wind gusts, moderate hail and heavy rainfall, as well as an isolated tornado, is approaching Perth Amboy and Staten Island. This is a very dangerous storm, take shelter if you are in this storm's path.



7:00 PM: The severe thunderstorm has moved into Warren County, however the strong thunderstorm in Sussex has intensified and is now a severe thunderstorm, also capable of producing damaging wind gusts and moderate hail.

The storms have changed directions. They are now moving ENE, and the first storm is now expected to affect SE Passaic and central/northern Bergen Counties in NJ, and may reach Rockland county in NY. The second storm will move through central/northern Rockland and Westchester counties.





6:26 PM: A severe thunderstorm is currently entering Warren County in NJ, and is quickly moving to the ESE. This storm will move through Morris, Essex and Hudson counties in New Jersey, and New York City also needs to watch this storm for potential impact. Expect damaging wind gusts up to 60-70 mph, small to moderate hail, and heavy rain with this storm, and an isolated tornado cannot be ruled out. Lighter rain and thunder will affect Sussex and Orange counties, though a strong storm is expected to move through parts of Sussex county.

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6:05 PM: The severe thunderstorm threat I have mentioned over the last few days is now becoming reality, with severe storms in Pennsylvania rapidly approaching the area. Due to the hot and humid conditions today, with temperatures reaching the 90 degree mark in Newark, New Jersey, as well as sunny skies, there is a lot of instability, which is enough to maintain these severe storms as they enter the area.

Areas affected by the storms: These storms have a history of producing strong to damaging wind gusts, with a path of wind damage reported with a storm currently approaching western New Jersey, south of Sussex County. These storms will continue to move ESE, with the greatest impact likely to be in the western and central parts of the area, in places just north of, along, and south of Interstate 80. Further north and east, into South Connecticut and parts of Long Island, rain and some storms are still likely, but they will probably not be as strong as the storms to the south/west.

Strongest storms/impact: The strongest storms will likely affect a path from Warren County in NJ, reaching anywhere from Bergen county through NYC into Middlesex County. Expect strong to damaging wind gusts, small to moderate sized hail, and heavy rain with these storms, and while none of them show a tornado vortex, an isolated tornado cannot be ruled out.

The next update will likely be posted tonight, however it may only be a brief update.

Tuesday, September 21, 2010

Sept 21: Summer-Like, Record Heat For Friday

The poll for the hottest temperature between Wednesday-Friday is now closed. Despite the models showing 90+ degrees, there have been 5 votes, and they are tied between 78-82 degrees and 82-86 degrees, which had 2 votes each. The other vote came for 74-78 degrees, and there were no votes for 86-90 and 90+ degrees.

This heat spell, a heat wave for the Mid Atlantic, is expected to be the most significant since early September, with temperatures likely returning into the 90s for NYC along with humidity. This will add the count of 90+ degree days for the area, and some places may tie or break their records for the most amount of 90+ degree days in a year.

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Tomorrow's Outlook:


Tomorrow will be the first day of the biggest warm up since the early September heat wave. With the warm front well to our northeast and a cold front approaching from the west, 850 mb temperatures will rise into the 16-18c range, leading to high temperatures reaching the mid to upper 80s inland, upper 80s to lower 90s in the immediate NYC area, and with a SW wind, Long Island and S CT will likely reach the mid 80s, with a few lower 80s possible near the coast and upper 80s in western Long Island.

Tomorrow night, as the cold front approaches, scattered thunderstorms, potentially severe, are expected for the western parts of the area. Some storms could reach the eastern parts of the area, but they will likely not be as strong.

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Thursday - Saturday: Summer-Like Weather Continues


Thursday: The cold front is expected to bring storms on Wednesday night, however this cold front will not move through, but rather stall to our north, keeping the very warm conditions in place. Yesterday, I raised my forecast highs to the mid-upper 80s in NYC, and I am keeping them at the same level with today's forecast. Partly cloudy skies are expected, and an isolated shower cannot be ruled out north of NYC. The cold front, however, will have a rather significant impact on places such as Maine, where high temperatures will drop into the 60s.

During Thursday night, the stalled front will start to lift northeast as a warm front, which will bring in warmer temperatures again. Overnight lows will be in the upper 50s to lower 60s inland, and lower to upper 60s for the rest of the area.

Friday: Friday, however, will be the hottest day of this heat spell, and has the potential to bring record heat from Washington DC to NYC. By the late afternoon, the warm front will have moved through, with mostly to partly sunny skies and a SSW wind expected. After I made my update yesterday, the NAM came into range and is hot, with high temperatures near the mid 90s for NYC, and the GFS has trended warmer as well, now showing high temperatures in the upper 80s for NYC, and it tends to be too cool by a few degrees for the daytime high temperatures.

Looking at the above, I have raised my forecast high temperatures, now expecting upper 80s inland, lower to mid 90s for the immediate NYC area, and Long Island/S CT in the mid to potentially upper 80s. With dew points in the 60s, this will lead to a potentially warmer heat index. Due to this, I issued a heat alert for the immediate NYC area (more details on that in the "Weather Alerts" page).

Saturday: With mild temperatures expected for Friday night as the cold front approaches, it is expected to move through during Saturday. High temperatures will be in the upper 70s to mid 80s, with scattered showers and thunderstorms possible.


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Sunday And Beyond: Storm Or Cool Down?

As I mentioned yesterday, there is uncertainty on what happens on Sunday. The uncertainty level is actually higher now, with possibilities ranging from a weak coastal low, to a low pressure moving north just inland, to no storm and a significant cool down. At this time, I have highs in the lower to upper 60s for Sunday with mostly cloudy skies in my 5-Day Forecast, but this is a relatively low confidence forecast and can still change.


Tropics: Igor Extra-Tropical, Lisa Active, Matthew To Form Soon


Igor finished its extra-tropical transition earlier today, and has been declared extra-tropical. Igor ended up closer to Newfoundland than originally thought, almost making landfall there, with reports of significant damage coming from there. Igor continued to grow in size up to its final advisory, with tropical storm force winds extending over 500 miles from the center. As a result, despite being far away from Nova Scotia, tropical storm force winds were very close to Nova Scotia.

Tropical Storm Lisa is currently slightly strengthening while slowly drifting, and is expected to intensify into a strong tropical storm, if not a weak hurricane. Afterwards, it will face an increasingly unfavorable environment, and will likely start to weaken. Lisa is currently not a threat to land.

Tropical Disturbance In Caribbean Could Become Major Hurricane

As I mentioned a few days ago, the models took a tropical disturbance in the Caribbean and developed it into a hurricane, with the potential track ranging from the Gulf of Mexico to the Bahamas. This tropical disturbance is currently active in the southeastern part of the Caribbean, and according to the National Hurricane Center, has a 50% chance of becoming a tropical cyclone over the next 2 days.

This tropical disturbance is expected to move west northwest, likely moving close to Nicaragua before turning more northwest, reaching the Yucatan Peninsula. The area where this will be active has not had a single tropical cyclone since Hurricane Felix in 2007, a destructive Category 5 hurricane which struck Nicaragua. Because of the lack of activity there, there are very high SSTs and Tropical Cyclone Heat Potential (TCHP) values. 95L is currently suffering from some wind shear to its north, but this wind shear is expected to weaken. Once it moves away from South America, with open waters and low shear, it could rapidly intensify, and it could become a major hurricane by the time that it reaches Nicaragua. If this becomes a tropical storm or hurricane, it will be named Matthew.

What happens from there, however, is still a question. It is possible that the storm crosses the Yucatan Peninsula and moves into the Gulf of Mexico, as the GGEM has been suggesting, or it follows the typical path of October storms, reaching the Yucatan and recurving northeast, directly affecting Cuba and making landfall in Florida as a hurricane, like the ECMWF is showing. If the GFS verifies, the storm could then go up the East Coast, however this is still uncertain. At this time, the majority of the models take it near or over Nicaragua, stall it between Honduras and Belieze for a few days, then take it north and NE towards Florida. Whether the first or second scenario happens, this storm is going to affect land directly, and if it does become a hurricane, it will not leave for good without directly affecting land.

Monday, September 20, 2010

Sept 20: Warmth To Last Until Saturday

Note:

- I have created a new page for the website, being the "Weather Alerts" page, replacing the "Severe Weather/Tropics" page. In there, I will create weather alerts, however they are not created by the National Weather Service, and should not be used instead of the NWS, but rather to see my thoughts on the potential for hazardous weather. Comments and suggestions on the page are appreciated, and will be taken into consideration when I decide whether to keep it or not.

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Today was a rather chilly day across the area, with highs back into the upper 60s to mid 70s, however temperatures are already dropping with what will be the coolest night yet this fall. I have issued a Frost Alert for the interior areas (more on that in the Weather Alerts page), where low temperatures will be in the upper 30s to lower 40s and could be as low as the mid 30s. The N/W suburbs of NYC and southern Connecticut will see lows in the lower to upper 40s, Long Island in the mid to upper 40s, and NYC in the lower to potentially mid 50s.

Tomorrow's Outlook:

Tomorrow will be another sunny and chilly day, with a south wind expected. High temperatures will be in the lower to mid 70s across most of the area, except for S CT/Long Island, which will be in the upper 60s to lower 70s.

Wednesday - Saturday: Very Warm

As I mentioned in yesterday's discussion, Wednesday is expected to be a very warm day, with highs in the mid to upper 80s inland and upper 80s to lower 90s in the immediate NYC area. Scattered showers and thunderstorms are expected overnight with lows in the upper 50s to lower 60s inland and lower to upper 60s for the rest of the area.

By Thursday, the cold front will stall close to the area, however high temperatures will still be rather warm for this time of the year. Due to the models trending warmer and changing the wind direction more towards the south/west than north/east due to trending north, I raised my forecast high temperatures, now expecting highs in the mid to potentially upper 80s for NYC and lower to mid 80s inland. Long Island/S CT will be cooler due to an onshore wind. Note that this is still subject to slight changes.

Friday will bring the return of warm conditions, with highs similar to, if not slightly warmer than those of Wednesday, however Friday night will be mild as the cold front approaches, with lows in the lower to mid 60s inland and the upper 60s to lower 70s in the immediate NYC area. Scattered showers and thunderstorms are expected for Saturday with highs in the mid 70s to lower 80s, but Saturday's highs are still subject to change.

Sunday-Monday: Storm, Or Cool Down?

By Sunday, uncertainty returns to the forecast. As I mentioned yesterday, a storm could form, however today's models backed away from this, and instead show a significant cool down with highs only in the upper 50s to lower 60s and lows in the 30s to lower 40s. I will post more on this tomorrow, once uncertainty could clear a little more.


Brief Tropics Update: A new tropical depression has formed in the eastern Atlantic, and will likely be named Lisa over the next few days. Lisa is not a threat to land at this time. Igor is currently turning extra-tropical, and will likely have its last advisory issued very soon.

Sunday, September 19, 2010

Sept 19: Return Of 90+ Degrees?

Notes:

- The 5-Day Forecast was updated for the area, including how warm it could get for the area between Wednesday and Friday. The poll for the hottest temperature during this time frame remains open until Tuesday, vote your thoughts if you have not done so yet.

- The tropics have been discussed today in the bottom of the post, where you will find details about hurricane Igor, potential Tropical Storm Lisa, and another tropical cyclone that could form next week in the Caribbean.

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Today was a rather mild day across the area, with high temperatures ranging from the upper 70s inland to the mid 80s in parts of the immediate NYC area. There are currently some isolated showers moving through, however these should only be isolated and light at best, with most locations staying dry. Tomorrow and Tuesday will be cooler, however a surge of warmth will bring much warmer temperatures for Wednesday through Friday, with some places potentially reaching the 90 degree mark once again.

Monday And Tuesday Outlook:

Tomorrow will be a mostly sunny day, with a cooler air mass expected. High temperatures will be in the lower 70s inland, mid 70s in the immediate NYC area, and lower to mid 70s for S CT/Long Island. Tomorrow night will bring very chilly temperatures as the cold air mass starts to exit, with low temperatures in the lower 40s and potentially upper 30s inland, mid to upper 40s with a few lower 50s for the N/W suburbs of NYC, mid to upper 40s for S CT, upper 40s to lower 50s in Long Island (with the exception of the cool spots in eastern LI), and lower to mid 50s in NYC.

Tuesday will start to warm up as a warm front approaches from the southwest, with high temperatures similar to, if not slightly warmer than those of Monday.

Wednesday-Friday : Two Storms, Big Surge Of Heat


**Note: I took my time to make a discussion for this time frame, discussing the likely scenario and the other possibilites. If this is too long for you to read, you can find the forecast temperatures for your area in the 5-Day Forecast page.**


On Wednesday, a warm front related to a storm well to our northwest will move through the area, bringing a much warmer air mass. 850 mb temperatures are likely to be near 18c, leading to high temperatures in the mid 80s inland and upper 80s in the immediate NYC area, with lower 90s also possible in NYC in the warmer case scenario. The GFS, however, is showing slightly cooler temperatures despite being colder than the rest of the models, with highs in the lower to mid 80s in NYC, and while this solution is not the most likely at this time, it also cannot be ruled out.

Overnight, the cold front will approach, and with a potentially favorable set up, scattered thunderstorms, potentially strong, are likely for the area. These storms, though, aren't likely to bring more than locally heavy rainfall, with generally light rainfall amounts likely.

On Thursday, it now appears that the warm air mass will stay far north enough to bring warm temperatures to the area, but how warm is the question as an east wind could limit the temperatures. The air mass, given that there is no rain expected, would support high temperatures in the lower to mid 80s inland and mid 80s for NYC, however this is in the warmer case scenario, and it could be cooler due to a SE-E wind and/or a slightly different placement of the stalled front. At this time, I am going slightly lower than the above, expecting highs in the lower 80s for NYC, and upper 70s to lower 80s inland with mid to potentially upper 70s for Long Island/S CT, but note that this is still subject to change.

Another storm will then organize to our northwest on Friday, however the models have trended slower and further north for this storm. While the models will still shift around a little over the next few days, I do think that a slightly slower and further north solution than yesterday's forecast is becoming more likely. 850 mb temperatures will rise into the 18c-20c range again, and with a SW wind returning, high temperatures could reach the upper 80s to lower 90s again in the immediate NYC area. The cold front, however, will be slow to reach the area, and will only start bringing rain by Friday night. With this, scattered showers and thunderstorms are expected.

The cold front could pass any time between late Friday night and Saturday afternoon, at this time I am going in between with a cold frontal passage during Saturday morning but note that I could shift it towards Saturday afternoon.

Weekend Outlook: Dry Saturday, Wet Sunday/Monday?

The cold front should move through on Saturday, bringing high temperatures closer to but still above average, potentially between the mid 70s to lower 80s. If the cold front on the models stays the same or trends slower, however, temperatures would likely be warmer, in the lower to upper 80s. By Sunday, the cold front should be to our south, however it is possible that the cold front nearly stalls, with a low pressure developing along the cold front, as some models have been showing. If this happens, there is uncertainty on where it forms and tracks and who gets rain, but any storm would be to our south, meaning that if we do get rain, it will likely be the steady, chilly type of rain. More details on this potential will be posted over the next few days, including who is likely to get rain and how much.


Tropics: Igor Weakening, Lisa And Matthew To Come Next


Hurricane Igor, currently a weak Category 1, has weakened faster than expected, and is barely a hurricane, though it is still producing strong winds and heavy rainfall in Bermuda. Despite this, however, Igor is undoubtedly one of the largest storms recorded in the Atlantic Ocean, leading to a greater impact on Bermuda than a typical Category 1 hurricane would have. Igor is then expected to move northeast and potentially weaken to a tropical storm, but then intensify again as it becomes an extra-tropical cyclone, absorbing the remnants of Julia at the same time.

Meanwhile, there are two potential tropical cyclone formations. An invest in the eastern Atlantic Ocean is becoming more organized, and could be named Tropical Storm Lisa over the next day or two. Lisa is currently not a threat to land.

The second potential, however, is a threat to land. All of the models are hinting at a low pressure developing into a tropical cyclone in the western Caribbean around Sunday or Monday the 26-27th. This is still in the longer range, and the models vary with the direction of this tropical cyclone, ranging from a hurricane in the Gulf of Mexico to a hurricane moving up the East Coast (which the GFS has been showing), however what we can take from this is that a tropical cyclone may form in the Caribbean and move north or NW, affecting land. If this potential stays, more details on it will come over the next few days.

Saturday, September 18, 2010

Sept 18: Warmth Returns On Wednesday

Note: The 5-Day Forecast was updated tonight. The poll on the hottest temperatures between Wednesday-Friday also remains open until Tuesday.

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Today was a nice day for the area, with highs generally in the lower 70s, though tomorrow will be warmer ahead of a cold front. Monday and Tuesday will be cooler, but afterwards there is the potential for what could bring the last 90 degree day or two for parts of the area.

Tomorrow's Outlook:

Tomorrow will be partly cloudy with a SW wind expected. High temperatures will be in the upper 70s inland, lower 80s in the immediate NYC area, and in the mid to upper 70s for Long Island/S CT. An isolated shower or thunderstorm is possible tomorrow night as a cold front moves through, however any shower should be light.

Monday And Tuesday: Cooler, Sunny

By Monday, a cooler air mass will move into the area. As I have thought, the models were too cold at first, and have trended warmer, now showing mid-upper 70s for parts of the area, however based on their history, I am thinking this could be a little too warm, and I am expected mid to potentially lower 70s in the immediate NYC area, lower 70s inland, and lower to mid 70s for Long Island/S CT. Overnight temperatures will be chilly, in the lower to mid 40s inland, mid to upper 40s for S CT, upper 40s to lower 50s for the N/W suburbs of NYC and Long Island, and lower to mid 50s for NYC.

On Tuesday, a warm front will approach from the southwest, however an east wind will limit the temperatures, with highs in the lower to potentially mid 70s for most of the area except Long Island/S CT, which should be in the upper 60s to lower 70s.

Wednesday-Friday: Significant Warm Up, Storms Possible

As I have mentioned over the last few days, a storm will organize well to our northwest on Wednesday, bringing in a much warmer air mass. High temperatures will likely rise into the upper 70s to lower 80s inland and lower to mid 80s for the immediate NYC area. The cold front moving through overnight, with scattered showers and thunderstorms likely and lows generally in the 60s. On Thursday, the frontal boundary will likely set up close to the area, however there is still uncertainty on the high temperatures, which could range from the mid 70s to lower 80s. Due to an east wind possible, I am leaning towards the lower end of this range at this time.

By Friday, another storm, but stronger and further south than Wednesday's storm, will affect the Northeast. This could bring in temperatures potentially warmer than those of Wednesday, which would be in the upper 80s to potentially lower 90s for the immediate NYC area. The cold front will then move through on Friday night, and with the set up in place, strong or potentially severe thunderstorms will be possible with the cold front.

Saturday-Sunday: Cooler, But Another Potential Storm?

After the cold front moves through, Saturday will bring drier conditions and cooler temperatures, with high temperatures near-below average, in the 60s and 70s for the northern Mid Atlantic, even though there is uncertainty on how strong the cold air mass is. On Sunday, however, a few models have been showing a storm affecting the area. The GFS is the most extreme, showing a nor'easter with lows in the 30s and potentially snow mixing with the rain for the interior parts of the area, however this solution is an outlier and is not expected to happen. This only started showing up on the models recently, so details for this time frame may change around over the next few days. Stay tuned for more details for next weekend.

Friday, September 17, 2010

Sept 17: Two Tornadoes Confirmed In NYC Yesterday

Blog Notes:

- The 5-Day Forecast was updated tonight.
- The poll for the hottest temperature between Wednesday-Friday remains open for the next few days. Vote your thoughts on the poll if you have not done so yet.
- With two tornadoes now having been confirmed, a storm summary will be posted on yesterday's event over the next few days.

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After yesterday's storms, where a tornado has been confirmed in central New Jersey with a high wind report in Queens, today was a much nicer day for the area. After the National Weather Service examined the damage, not one, but two tornadoes were confirmed in NYC, the first an EF0 in Brooklyn near Park Slope, and the second an EF1 tornado in Queens near Flushing and Bayside. There was also a microburst observed near Forest Hills, Queens. A storm summary will be posted on this over the next few days, with more details on what happened.

The next few days will be dry and comfortable, with slightly warmer temperatures on Sunday and colder temperatures on Monday, but the warm conditions may return again by mid-late next week.

Tomorrow's Outlook:

Tomorrow will be a partly sunny day, with clearing skies likely and a SSE wind expected. High temperatures will rise into the mid 70s inland and in the immediate NYC area, with lower 70s for Long Island and S CT.

Sunday - Tuesday: Warm, Then Cooling Down

On Sunday, as the cold front approaches the area, temperatures are expected to warm up, and will likely reach the lower 80s for the immediate NYC area, with mid to upper 70s for the interior and Long Island/S CT. An isolated shower or thunderstorm is possible, however there is a low chance of this happening, and partly sunny skies are expected.

A colder air mass will move into the area by Monday, however yesterday's models were likely overestimating the intensity of this cold air mass, and have since trended warmer. High temperatures in the upper 60s to mid 70s are expected for the area on Monday, with overnight lows in the lower to mid 40s inland, mid 40s to lower 50s for the N/W suburbs of NYC and southern CT, upper 40s to lower 50s for Long Island, and lower to mid 50s for NYC. Tuesday will be slightly warmer as a warm from approaches from the SW.

Wednesday-Friday: Return Of Warmth

As I have mentioned with my updates over the last few days, a significant warm up is possible by mid-late next week. A storm on Wednesday will track to our north and west, however this will also draw in a much warmer air mass. 850 mb temperatures are expected to pass 15c and may approach 20c, leading to high temperatures potentially rising into the lower to mid 80s, and upper 80s may be possible in the warmer case scenario, although no model shows this at this time. Scattered showers and thunderstorms are possible for Wednesday night as the cold front moves nearby, but widespread moderate to heavy rain is unlikely.

The cold front is expected to approach the area by Thursday, however there is uncertainty on how far south the warm air mass retreats. It is possible that it stays far north enough to bring another day of low 80s for the area, or it moves south to give highs potentially near the mid-upper 70s. By Friday, however, another storm, potentially stronger, will likely organize well to our northwest, and should draw in a potentially warmer air mass. If some models verify, this will bring upper 80s for the area, with lower 90s even possible, however this is still uncertain. More details on this potential will come over the next few days.

By the weekend, a cooler air mass should move in, bringing temperatures back to the near-below average range.


Tropics: Mexico Hit By Karl, Bermuda Next In Line


Hurricane Karl made landfall earlier today in southern Mexico, as a Category 3 hurricane. Karl peaked as a strong Category 3 hurricane before making landfall, and could've reached Category 4 intensity, however interaction with Mexico slightly weakened Karl before landfall. Karl set the record for the southernmost major hurricane in the Gulf of Mexico, being very close to the Mexican coast, while most hurricanes in that region are much further north.

Hurricane Julia, meanwhile, has weakened and is barely a hurricane, and due to an unfavorable environment, is expected to continue weakening. Julia may become a tropical depression over the next few days, and Julia or its remnants will likely be absorbed by Igor once it is almost an extra-tropical storm.


Hurricane Igor:

Hurricane Igor has weakened more than expected, and is now down to a Category 2 hurricane. Despite this, Igor has grown in size even more, and is now even larger than other massive hurricanes, such as Ike of 2008 and Katrina of 2005. Igor is expected to maintain its intensity for the next few days, but may weaken to a Category 1 hurricane by Sunday or Monday.

Igor's eye is expected to pass very close to, if not over Bermuda. This would bring hurricane conditions to the island, with tropical storm conditions lasting for a longer period of time, mainly due to Igor's massive size. Igor will be weaker than Fabian of 2003 was when passing near Bermuda, but it will still be capable of producing potentially significant damage there. Igor will then turn northeast and stay out to sea while speeding up and turning extra-tropical.

Thursday, September 16, 2010

Sept 16: Dry And Comfortable Weekend Ahead

After today's damaging storms in the immediate NYC area, which caused widespread damage from central NJ through Brooklyn and Staten Island into western Long Island, the area will get a break from the stormy conditions. It has not been determined yet whether this was a tornado or not, though a storm summary will be posted on this event once it is clear what caused the damage.

For the short term, some light to moderate rain will fall before midnight, with another round of storms possible after midnight, but they will not be as strong as the storms that went through for this afternoon. The round after midnight is actually the line that was originally supposed to be the strong storm line, but the afternoon line became stronger.

Tomorrow's Outlook:

Tomorrow will start out mostly cloudy, then clear to mostly sunny by the end of the day, with a north wind expected. High temperatures will be in the mid 70s for most of the area, though a few upper 70s cannot be ruled out for the immediate NYC area.

Weekend Outlook: Dry, Comfortable

On Saturday, a slightly warmer air mass will approach the area, but highs will be similar to those of tomorrow, with mostly sunny skies expected. Sunday, however, will be warmer as a cold front approaches from the west, bringing partly cloudy skies and a chance of a few showers or thunderstorms. High temperatures will be in the mid to upper 70s inland and in S CT/Long Island, with the immediate NYC area in the upper 70s to lower 80s.

Monday And Tuesday: Chilly Conditions Return

By Monday, a trough will move into the area behind the cold front, and while it will not be long lasting, it will bring below average temperatures. Highs will range from the upper 60s (potentially mid 60s) inland, to the lower 70s in the immediate NYC area, with upper 60s to lower 70s for Long Island/S CT. Overnight lows will be chilly, similar to those of this morning, with Tuesday slightly warming up.


Late Week Warm Spell

By Wednesday, the storm track will shift well to the northwest of the area, and as a result, a large ridge is likely to build into the area. High temperatures are expected to reach the 80s by Wednesday, with 90s possible for the southern and central Mid Atlantic. There is uncertainty on whether Wednesday or Friday is the hottest day, but the hottest temperature during this time frame could potentially reach the mid-upper 80s, with a few models even showing lower 90s ahead of the cold front. Stay tuned for more details.




Tropics: Karl Intensifying, Igor And Julia Weakening


Hurricane Igor: Down To A Category 3

Hurricane Igor, the powerful hurricane that is now one of the biggest hurricanes on record in the Atlantic Ocean, has been downgraded to a Category 3 hurricane. Igor is moving slowly northwest, and will turn more north with time, and for at least the next few days, it is expected to maintain its intensity. Afterwards, as a Category 2 or 3 hurricane, Igor will approach Bermuda, and while the eyewall may stay SW of the island, hurricane conditions are becoming more likely in Bermuda, especially as due to Igor's large size, even a near miss will still bring very dangerous conditions to Bermuda.

Hurricane Fabian of 2003 was one of the worst storms to affect Bermuda, and was a Category 3 hurricane when it was near Bermuda. While it is uncertain how bad Igor will be in Bermuda, it is expected to have a potentially significant impact on the island, and it could produce significant damage.

Hurricane Julia:

Hurricane Julia has significantly weakened over the last day, and is barely a Category 1 hurricane. Julia is expected to continue weakening, and could be absorbed by Igor in the future. Julia is not a threat to land.

Hurricane Karl:

Karl has managed to keep a very organized structure while inland, leading to a faster intensification once moving offshore. Karl is now a strong Category 1 hurricane approaching Mexico, quickly strengthening, and I am expecting Karl to peak as a Category 3 hurricane before making landfall in Mexico.

Sept 16 Noon: Strong Storms

6:14 PM: The severe thunderstorm has intensified and has become more organized, and during the time that I did not update the website earlier this hour, the National Weather Service issued a tornado warning for Brooklyn, something that doesn't happen frequently there. The warning has been already cancelled.

The storm is currently in western Long Island and southern Connecticut, moving ENE, and the storm will be just north of Lake Grove in Long Island before moving offshore. Expect to see heavy rain in most of southern Connecticut, with the severe thunderstorms affecting the coastal areas of southern Connecticut. Expect rainfall amounts up to 1 inch in a very short period of time out of this severe storm.


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5:00 PM: Due to a slight change in the forecast set up for the storm, the squall line is reaching the area earlier than expected, and is nearing New York City, moving NE quickly. Places from Rockland/Westchester counties and furthers south/east/NE can expect to see a quick round of strong to potentially severe thunderstorms, producing heavy rainfall, with up to an inch possible in a short period of time, and damaging wind gusts up to 60 mph. Small to moderate hail is also expected with some of these storms. The strongest storms will be from Middlesex County into western Long Island.

Behind this squall line, light to moderate rain will approach and affect the area through the overnight hours, but the rain will not be very heavy, and at least a total of 0.7 to 1.4 inch of rain is possible by the time that the storm ends, with locally higher amounts.

Wednesday, September 15, 2010

Sept 15: Stormy And Windy Thursday Night

Notes:

- The 5-Day Forecast was updated tonight.
- The poll for your thoughts on the hottest temperature around Wednesday remains open. Vote your thoughts in the poll, which will remain open until Sunday.

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Today brought mostly sunny skies and chilly temperatures as a cool air mass moved into the area, with highs ranging from the mid-upper 60s inland to the upper 60s to mid 70s in the immediate NYC area. Tonight will be a very chilly one, with lows in the 40s for most of the area except for NYC and most of Long Island.

Tomorrow's Outlook:

Tomorrow will bring increasing clouds to the area, with a south wind expected. With a sharp gradient in temperatures expected, the interior areas as well as Long Island/S CT will peak in the lower 70s with a few upper 60s possible, lower to mid 70s north and west of NYC, and in the mid to upper 70s for NYC and closer to the coast. Places SW of NYC may reach the lower 80s.

Meanwhile, a strong storm will be approaching the area from the northwest. The storm track will stay to our north, leading to heavy rain in the interior Northeast and New England, with a round of severe storms for the western parts of the region south of the storm track due to the cold front. South of the storm track, a squall line will approach the area along the cold front, affecting the area between 8 PM and 4 AM. Locally heavy rainfall is expected along with thunderstorms, with strong wind gusts possible with the storms. Other than the storms, windy conditions are still expected on Thursday night, especially for Long Island and S CT, where wind gusts may reach 50 mph. Low temperatures will stay steady overnight, and may slightly rise ahead of the storms.

Friday - Sunday: Cooler, Then Warming Up

On Friday, mainly cloudy skies are expected, with highs in the lower to mid 70s, though the cloud cover will be clearing by the late day. Saturday will be a comfortable day with slightly warmer temperatures, with Sunday warming up to the mid 70s to lower 80s ahead of a cold front. Scattered showers are possible on Sunday and Sunday night due to the cold front.

Monday - Wednesday: Cool, Then Unseasonably Warm

After the cold front moves through on Sunday, a cooler air mass will enter the area for Monday. There is uncertainty with how strong the air mass is, however at this time I am thinking 850 mb temperatures could be near 6c, leading to highs in the upper 60s to mid 70s in the area, with lows on Monday night chilly, similar to those of tonight. Tuesday is likely to be another relatively chilly day.

By Wednesday, however, a strong storm will organize well to our northwest, drawing in an unseasonably warm air mass into the region. High temperatures will likely pass the 80 degree mark, and according to some models, may reach the 90 degree mark ahead of the cold front, which will move through around Thursday, bringing some more rain to the area and cooler temperatures. Stay tuned for more details on this time frame.


Tropics: 2 Hurricanes Active, Another One To Follow


Hurricane Igor:

Hurricane Igor last night quickly strengthened, and peaked at 155 mph last night, just below Category 5 intensity, however it is possible it may have peaked as one. Igor has since weakened due to a less favorable environment, but has maintained Category 4 intensity. Igor is currently organizing itself and may slightly strengthen again, but it has probably reached its peak.

For the longer range, Igor will continue to move WNW to NW, and will switch towards a NNW then north track, taking it close to Bermuda as a Category 2 or 3 hurricane. Bermuda needs to closely follow Igor, as it may bring hurricane or tropical storm conditions to the island.

Hurricane Julia: Unexpected Strengthening Leads To Cat 4

Last night, Hurricane Julia was slowly strengthening and was likely to peak as a category 2 hurricane, with a window of at lteast 2 days for intensification, but unlike what all of the forecasts and models suggested, Julia unexpectedly rapidly intensified, and like Igor, reached Category 4 intensity this morning. This was a notable event, as in history, there was only one other occasion where two category 4 hurricanes were present at the same time in the Atlantic Ocean, and Julia also set the record for the most intense hurricane this far east, breaking the previous record Hurricane Fred set last year as a Category 3 hurricane.

With a less favorable environment ahead of Julia, weakening is expected, and Julia most likely has reached its peak.

Tropical Storm Karl: Soon To Be Hurricane

As expected, Karl quickly strengthened yesterday, and made landfall in the Yucatan Peninsula with 65 mph sustained winds. Karl is currently over the Yucatan and is down to a 40 mph tropical storm, however it will soon enter the Gulf of Mexico. Despite Karl likely to be a tropical depression by then, with a favorable environment there, quick strengthening is likely once again, and Karl is expected to become a hurricane by the time that it makes landfall in Mexico.

Brief note on overall season: When lowering my call from 15-18 to 12-16 named storms, it was with the thought that some waves would not develop. While I did expect much higher activity by this time period, almost all of the tropical waves developed, which exceeded my expectations. While it is already late in the season, I am thinking that we could end up with 16 to 19 named storms, 8 to 12 hurricanes, and 4 to 7 major hurricanes when the season ends.

Tuesday, September 14, 2010

Sept 14: Update On Tropics, Storm Thursday Night

Notes:

- A new poll has been added for your thoughts on early next week and what temperatures it may bring. Vote your thoughts in the poll, which will close on Sunday.

- The 5-Day Forecast has been updated for the area.

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With a partly sunny day today, things are now cooling down as a cold air mass enters the area. Low temperatures tonight will be very chilly, in the 40s for most of the area except for Long Island and NYC. Despite this, things will warm up in the longer range, with more rain likely for Thursday night and potentially strong storms.

Tomorrow's Outlook:

Tomorrow will be a mostly sunny day. High temperatures will be in the upper 60s to lower 70s inland, and in the lower to mid 70s for the rest of the area.

Thursday Night Storm Update:

On Thursday, highs will peak in the lower to mid 70s for most of the area with upper 60s-lower 70s for Long Island/S CT due to increasing cloud cover ahead of a cold front. Most of the storm's rain will fall well to our north, but a cold front will pass through overnight, bringing a squall line with locally heavy storms. Gusty winds are also possible on Thursday night, especially when the storms move through. Rainfall amounts up to 1/4 inch are expected, though amounts locally up to 1/2 or 3/4 inch are possible, mainly towards the northern and NW parts of the area.

Temperatures will be steady or slowly rise before the cold front moves through, with dropping temperatures and clearing skies afterwards. Friday will be a dry and partly sunny day with highs in the mid 70s across the area.

Saturday And Longer Range: Warm Up, Significant Warm Up Possible

On Saturday, a strong cold front will be well to our west, with warming temperatures, reaching the mid 70s for most of the area, but upper 60s to lower 70s for S CT/Long Island. On Sunday, as the cold front approaches but weakens, highs will reach the upper 70s to lower 80s for NYC, with a slightly cooler air mass possible for Monday, though highs shouldn't be much below average. By Tuesday and Wednesday, however, a strong storm could organize to our NW, and it could draw in a large ridge, with highs in the 80s and even lower 90s for the Mid Atlantic up to NYC. Stay tuned for more details on this time frame.


Tropics: Igor, Julia, And Now Karl


Hurricane Igor: Almost A Category 5 Hurricane

Hurricane Igor, currently east of the northernmost Leeward Islands, has weakened slightly over the last day, but is currently strengthening rather quickly, and with a favorable environment, may briefly become a Category 5 hurricane late tonight, however this is uncertain as Igor's eyewall structure is not as organized as it previously was, being why it is more likely to stay as a high-end Category 4 hurricane. To Igor's northwest, there is a less favorable environment, and Igor should start to weaken in the next few days. About its track, it is not expected to affect the East Coast directly, but at this time, it is likely to approach Bermuda. While the models show Igor slightly west of Bermuda, it could end up close enough to bring hurricane conditions to the island. Stay tuned for more details on Igor over the next few days.

Hurricane Julia: Nearly A Category 2 Hurricane

Hurricane Julia in the eastern Atlantic Ocean is slowly intensifying, and is almost a Category 2 hurricane, if not one already. Due to increasingly unfavorable conditions to Julia's NW, it is likely to peak over the next day or two, then start to weaken. Julia will stay away from land.

Tropical Storm Karl To Make 2 Landfalls In Mexico

The tropical invest in the Caribbean that has been briefly mentioned a few days ago has been named Tropical Storm Karl today, and is currently at 45 mph sustained winds and a minimum pressure of 999 mb. Karl is running out of time before making landfall in the Yucatan peninsula, however with a favorable environment, it is quickly intensifying, and may reach 60 mph before its first landfall. Afterwards, it should weaken to a tropical depression, but with a favorable environment again in the southern Gulf of Mexico, Karl will likely become a strong tropical storm before its second landfall, and a Category 1 hurricane cannot be ruled out.