Tuesday, August 31, 2010

Aug 31: Earl's Preliminary Impact Forecast

Brief Heat Update: Today and tomorrow will likely be the hottest days until next year for the area, with the current temperatures already very hot, ranging from the lower 90s inland to the mid-upper 90s for the immediate NYC area. A few 100 degree reports are even showing up not too far SW of the area. Tomorrow will be similar in terms of temperatures, with Thursday slightly cooling down.

Hurricane Earl: Weakening, But Still A Major Threat For The East Coast

Earl's Current Observations: Earl is currently a Category 4 hurricane, with sustained winds at 135 mph and minimum pressure at 940 mb. Earl has been stronger earlier today, however it is currently weakening, with more on that below. Earl is currently north of Hispaniola, and is moving west northwest with occasional hints of a NW movement.

Earl's Intensity Forecast: As mentioned above, Earl is currently weakening. It continued to rapidly intensify when I posted yesterday's update, but due to increased shear, a lot of dry air to its northwest and an eyewall replacement cycle, Earl is currently weakening, and I would not be surprised if we see Earl downgraded to a category 3 hurricane by the end of today. Earl should complete its eyewall replacement cycle soon, and could intensify, as there is also decreasing shear ahead of Earl, but the dry air will still be there and likely prevent rapid intensification of Earl. As a result, I have Earl weakening to a category 3 tonight, potentially back up to a category 4 tomorrow, then down again to a category 3 hurricane as Earl starts to weaken further north.

Earl will then interact with the approaching cold front to its west on Friday-Saturday, and will start to lose tropical characteristics, becoming an extra-tropical cyclone by the time that it is near Nova Scotia.

Earl's Track Forecast: Earl continues to move west northwest and is still south of a lot of the models' predictions from yesterday, which a lot of the models have trended west. The latest GFS run dumps heavy rain on Long Island with rainfall amounts over 1/2 inch extending as far west as almost central NJ, however this could be a little too far west as the GFS is not very good in handling sharp cut off lines. The NAM is also close to the coast, as well as the ECMWF and NOGAPS, which both of these models showing a landfall for eastern North Carolina and Cape Cod. Looking at the above, as well as Earl still moving WNW, I decided to shift my track further west, taking Earl closer to the coast but not showing a landfall yet. It is possible that this track may trend a little more west, with the probability for a landfall in eastern North Carolina and/or Cape Cod increasing. If the models become more consistent on this solution, I will likely reflect it in tomorrow's forecast.

Forecast Preliminary Impact Map For The East Coast

Earl is expected to be a Category 2 hurricane while moving east of the East Coast. At this time, the exact impact is uncertain, but some details are likely, including possible hurricane conditions for Cape Cod and eastern North Carolina.

At this time, I went acording to the scenario I posted in my forecast map, as well as other forecast models. Note that this is only according to my current thinking, and can still change. I am thinking that Earl will move close to eastern NC and Cape Cod, where hurricane conditions are possible. Strong winds are likely for these areas, as well as very heavy rainfall amounting to several inches. Further west, including southeastern Virginia, the Delmarva Peninsula, eastern New Jersey, Long Island/S CT and a good part of eastern New England, tropical storm conditions are possible, including heavy rainfall up to 1-3" possible and tropical storm force winds (40-70 mph) with stronger gusts. Further west of this area, some rain is expected, with up to an inch, but the worst will stay in the areas mentioned above. If the models stay consistent or trend west, however, places west of the yellow area will also be capable of seeing the conditions mentioned above.

As I previously mentioned, the scenario above can still change. It is possible that Earl trend slightly further east, with the hurricane conditions staying offshore, or Earl trends west, with Tropical Storm conditions covering most of the NYC area, with hurricane conditions possible even in eastern Long Island.

Over the next few days, updates on Earl will be posted more frequently, with the next update to be posted tomorrow in the early morning, reflecting the latest data on Earl and any potential change in the forecast.

Monday, August 30, 2010

August 30, 2010: Hurricane Earl Update

Notes:

- As I mentioned yesterday, for the next few days, the updates will focus on Hurricane Earl, with some updates on the ongoing heat wave. The poll for Earl is still open until Wednesday on whether Earl will directly affect the NYC area or not, please vote in the poll if you have not voted yet.

- The 5-Day Forecast was updated today for Friday, but please note that it is a low confidence forecast. While I did not update Saturday's forecast today (I will update it tomorrow), Saturday will bring cooler temperatures to the area, with upper 70s to lower 80s possible, with Sunday even cooler.

Heat Wave Update:

Today is another hot day across the area, with high temperatures generally in the upper 80s to lower 90s. Tomorrow will be hotter than today though, as temperatures warm up to the lower to mid 90s inland, mid to upper 90s for the immediate NYC area, and with a SW wind, Long Island and S CT reach the upper 80s to lower 90s with a few mid 90s possible. Wednesday will have similar temperatures, with Thursday slightly cooling down.


Hurricane Earl: Almost A Category 4 Hurricane


Earl's Current Observations: Earl is currently a strong Category 3 hurricane, with sustained winds near 125 mph and minimum pressure near 955 mb. Earl is generally moving west northwest at 14 mph, even though it constantly switches back and forth from a northwest to a due west motion. Earl is located northeast of Puerto Rico, and its center should stay to the north of Puerto Rico.

Earl's Intensity Forecast: Earl is currently rapidly intensifying, and while it is a category 3 as of NHC's 2 PM update, it will likely be a category 4 update by 5 or 8 PM. Earl has a very favorable environment ahead of it, and will continue to intensify rapidly. I currently expect Earl to peak as a strong Category 4 hurricane (sustained winds 145-155 mph). While the following scenario is not shown at this time, it is possible that Earl continues to rapidly intensify and may become a weak category 5 hurricane, however this is unlikely at this time and is not reflected in the forecast map.

By Friday, when Earl should be ESE of Long Island, it should start turning extra-tropical as Earl will be interacting with the cold front, as well as cooler SSTs. Earl is likely to be extra-tropical by the time it is near Nova Scotia.

Earl's Track Forecast: Earl is currently moving west northwest and is just northeast of Puerto Rico, and even though it is slightly north of where I expected it to be at this time, it will keep moving WNW for the short term before moving more northwest due to ridging to Earl's east. Earl is then going to approach a cold front to its west on Thursday and should turn more north, then start to recurve NNE, but the big question at this time is how far west Earl ends up at that time, as that will indicate how much of an impact Earl will have on the NYC area. If Earl is near or just east of Cape Hatteras, NC, it could bring tropical storm conditions for Long Island, otherwise Long Island should see light rain and some winds but the worst of Earl will stay to the east.

The models continued to trend west, with this morning's 00z GFS run bringing heavy rain and strong winds to Long Island with some rain for NYC and NE NJ. The GFS has adjusted eastwards since then, but it has yet to lock on a specific track for Earl. Most of the models have shifted west, and while I am keeping my forecast track for this time frame near yesterday's forecast, it is possible that the track may have to be adjusted further west tomorrow. Cape Cod and eastern NC are likely to have the biggest impact from Earl at this time, with heavy rain and hurricane conditions possible, with Earl also likely to move over Nova Scotia as an extra-tropical storm. For now, I am thinking Long Island could see moderate rain and windy conditions with light rain for NYC, but this will likely change as details become clearer. Stay tuned for more details about Hurricane Earl.

Sunday, August 29, 2010

August 29, 2010: Tracking Heat Wave, Hurricane Earl

Blog Notes:

- The poll for Earl remains open until Wednesday, please continue to vote your thoughts in the poll on whether it directly affects the area or not.

- The 5-Day Forecast page was updated tonight, but the Day 5 (Friday) forecast was not updated, more details on that are below.

- As Earl continues to threaten the area, for the next few days, the updates will focus on the heat wave and Earl, and less on the longer range.

Tomorrow's Outlook:

Tomorrow should be another sunny, dry and hot day across the area, with high temperatures in the lower 90s inland, and in the mid 90s for the immediate NYC area. With a NW wind, Long Island and S CT will reach the lower 90s.

Tuesday - Thursday: Hottest Days Of The Heat Wave

On Tuesday, despite the warmest 850 mb temperatures shifting to the SW of the area, temperatures are likely to only get warmer, with high temperatures reaching the lower to mid 90s inland, mid to upper 90s for the immediate NYC area, and with a west wind, Long Island and S CT will reach the lower to locally mid 90s. Wednesday and Thursday will have similar temperatures for the western and central parts of the area, but with a SW wind, Long Island and S CT will reach the upper 80s to lower 90s, with a few mid 90s possible for western Long Island.

Friday, however, has a very low confidence level due to Earl, and at this time solutions range from dry conditions, to scattered storms from the cold front, or heavy rain and wind directly related to Earl. Due to this, the Friday (Day 5) forecast was not updated today, but it will likely be updated tomorrow.


Hurricane Earl: Forecast Map And Discussion


Earl's Current Observations: Earl is currently a weak Category 1 hurricane, with sustained winds at 75 mph, and minimum pressure at 978 mb. Earl is moving west northwest at 15 mph, and is approaching the northernmost Leeward Islands.

Earl's Intensity: Earl has intensified to a hurricane early today, and is currently steadily intensifying. Earl has a very favorable environment ahead of it, and if Earl does not suddenly weaken, rapid intensification is a good possibility. From yesterday, it appeared that a Category 4 hurricane became a possibility, and if nothing disrupts Earl's intensification, it could reach Category 4 (130 to 155 mph) intensity as early as Tuesday. It is expected to maintain Category 4 or upper-end category 3 intensity until at least Friday or Saturday, when it should be close to Cape Cod, as it should begin extra-tropical transition. Earl is likely to become extra-tropical by the time it reaches the Nova Scotia area.

Earl's Short Term Track: Earl has consistently been moving further south than expected by the models, and as a result, Earl is now likely to directly affect the northernmost Leeward Islands, with Puerto Rico and northern Hispaniola possibly seeing tropical storm conditions. The latest models continue to shift south and west with Earl's track, now showing a near miss for eastern North Carolina and Cape Cod. Earl continues to move west northwest, and it is expected to continue on this path for the next day or so. Afterwards, Earl will start turning more northwest with ridging to its east, while a cold front starts to approach from its west.

Earl's Long Term Track: By Thursday, the question is how far west Earl ends up, as that will show where Earl is going to end up. After Thursday, Earl will interact with the cold front to its west and start to transition into an extra-tropical storm, but until then, it will likely be a major hurricane at this time, so if it affect the East Coast, we are not talking about a tropical storm with some heavy rain and wind, but a major hurricane. At this time, I am leaning towards a track offshore but close to the coast, with Earl passing not too far east of Cape Hatteras before starting to recurve, then passing not too far SE of Cape Cod, with Nova Scotia potentially in Earl's path. If Earl ends up further west on Thursday, which would put it right near Cape Hatteras, Earl would recurve further west, with the coast up to Cape Cod seeing direct effects from Earl.

There is still relatively low confidence on where Earl exactly ends up, being why Friday's forecast for the area has a very low confidence level, but residents along the East Coast from North Carolina to Cape Cod need to closely monitor Earl and where it ends up, as any slight westward trend could put these places in Earl's path, and whether it directly affects the coast or not, Earl is still likely to have a significant impact on the beaches. More details will come on Earl over the next few days.

Saturday, August 28, 2010

August 28, 2010: Keeping An Eye On The Tropics

**Reminder: The poll on Tropical Storm Earl and whether it will directly affect the area or not is still open, and will remain open until Wednesday. Vote your thoughts on the poll, which is in the upper right corner of the page, below the radar.**

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With sunny skies and dry conditions still in place across the area, today is slightly warmer than yesterday, with high temperatures in the upper 70s to mid 80s. Temperatures, however, will warm up as a 5-day heat wave bring temperatures to the mid 90s across parts of the area between tomorrow and Thursday. Meanwhile, however, the tropics are becoming increasingly active, and will need to be closely monitored, as both Earl and what could be Fiona, will have an impact on at least parts of the East Coast, whether they directly affect the area or not, and may even affect the area.

Tomorrow's Outlook:

Tomorrow will be another sunny and dry day, however it will also be the first day of the heat wave. High temperatures are expected to be in the upper 80s to lower 90s inland, lower to mid 90s for the immediate NYC area, and in the upper 80s to lower 90s for Long Island and S CT. A WNW wind is expected.

Monday - Thursday: Heat Wave Continues

For Monday, temperatures will be hot once agin, with mid 90s expected for the immediate NYC area, however the models are showing the warmest 850 mb temperatures to our south, where Virginia up to Washington DC sould be in the upper 90s, with a few lower 100s possible. Tuesday will have similar temperatures, with Wednesday and Thursday likely to be slightly warmer as the warmest 850 mb temperatures move into the area, leading to high temperatures in the lower to mid 90s inland, mid to potentially upper 90s for the immediate NYC area, but with a SW wind, Long Island and S CT will not be as hot. Thursday, however, is likely to bring increased cloud cover, as a cold front should approach.

Thursday - Saturday: Cold Frontal Passage, Or Earl?

A cold front is expected to approach the area by Thursday, however the big question at this time is if Earl is close to the area or not. I am planning on having a detailed discussion on Earl tomorrow, however at this time, Earl slightly weakened, due to the LLC being briefly separated from the main convection. Since then, Earl's LLC has gotten back under the convection, however Earl is moving very quickly, at 23 mph, and will have to slow down in order to intensify significantly.

This brief separation of Earl's convection and its LLC, however, pushed Earl further south, and Earl is now likely to directly affect the northern Leeward Islands and potentially Puerto Rico as a strong tropical storm or weak hurricane. These areas should closely monitor Earl over the next day. Earl being further south and faster, however, increases Earl's chances of having a direct impact on the East Coast.

Earl will then approach the Carolinas while the cold front is still to its west, and if the timing of the cold front is supportive, in the westernmost possible scenario, Earl may make landfall in eastern North Carolina, and as the cold front starts to push it out to sea, Earl will recurve north then NE, passing very close to the coast up to Cape Cod, including eastern Long Island, before going out to sea. If Earl starts to slow down and recurves earlier, as the current scenario expects, it will likely stay offshore, but it would be close to the coast, especially near eastern North Carolina and Cape Cod. The eastern scenario is that Earl starts to recurve very early, and passes very close to Bermuda, however this scenario is not too likely at this time.

While there is a lot of uncertainty on where Earl tracks, residents along the coast from eastern North Carolina to eastern New England need to monitor Earl, as while there is relatively low confidence at this time, Earl could affect these areas. More details will come on Earl over the next few days.

Longer Range: Cool Down, Warming Up Again, Then Fiona?

Whatever happens with Earl, a trough is still expected to move into the area by the weekend into the early week, bringing below average temperatures with high temperatures generally in the 70s across the area. By the middle of next week, however, the models are expecting another ridge to build into the East Coast, and a warm up is possible by then with above average temperatures.

Meanwhile, however, 97L, which should likely become Tropical Storm Fiona, is expected to strengthen into a hurricane, potential major hurricane according to most of the models, and with the set up at that time, they are showing potential Fiona making landfall somewhere along the East Coast. While it is too early to know what happens with this, as this is still far in the longer range, and there is low confidence with the storm track at this time, this invest also needs to be watched for potential impact on the eastern US due to the pattern in place. More details will also come on this invest over the next few days.

Friday, August 27, 2010

August 27, 2010: Heat Wave To End By Friday

Blog Updates:

- The 5-Day Forecast has been updated for the area.
- The poll for this coming week's forecast pattern has ended with a total of 7 votes, here are the results:

2 - Below Average Temperatures
0 - Average Temperatures
3 - Above Average Temperatures
2 - Heat Wave

The newest poll is about whether Tropical Storm, future hurricane Earl will affect the area or not. Vote your thoughts on this in the poll, which will close on Wednesday.

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Sunny conditions have now returned to the area, and are expected to stay in place for the next week. Today was a comfortable day in the area, peaking in the mid 70s to lower 80s across the area, however from this point, temperatures will only become warmer, as what will be potentially one of the last yet one of the most powerful heat waves of the summer will start on Sunday.

Tomorrow's Outlook:

Saturday will be a nice day, with sunny skies, dry conditions and a north wind. High temperatures will be in the lower to mid 80s for most of the area, with mid 80s expected for the immediate NYC area.

Sunday - Thursday: 5-Day Heat Wave

Sunday will be the first day of a 5-day heat wave for the area, with high temperatures rising into the upper 80s to lower 90s inland, lower to mid 90s for the immediate NYC area, and upper 80s to lower 90s for Long Island and S CT. By Monday, hotter temperatures are expected with 850 mb temperatures near 20c, with high temperatures in the lower 90s inland and the mid 90s for the immediate NYC area. A few places southwest of NYC could reach 95-97 degrees, however these temperatures should not be widespread yet.

For Tuesday, the warmest 850 mb temperatures will shift to our west, but temperatures will still be hot, in the upper 80s to lower 90s inland, and lower to mid 90s for the immediate NYC area. Wednesday, however, should be the hottest day of this heat wave as the warmest 850 mb temperatures shift into the area, between 20c and 22c. High temperatures will be in the lower to mid 90s inland, mid to upper 90s for the immediate NYC area, but with a SW wind expected, Long Island and S CT will not be much hotter, in the lower to potentially mid 90s.

Thursday will likely be another hot day, with temperatures in the upper 80s to lower 90s inland and lower to mid 90s for the immediate NYC area with a SW wind expected again, however more cloud cover is likely ahead of a cold front.

Friday And Saturday: Cold Front And Rain, But Could Earl Move In?

**Note: As the previous poll has ended, I opened a new poll in the top right corner of the blog below the radar, about whether Earl could affect the area directly or not. Vote your thoughts in the poll, which will close by Wednesday.**

There are two possible scenarios for this time period, at this time I am leaning towards one but I will also discuss the other.

The scenario I am leaning towards is the one where Earl stays to our east, but note that it can change. In this scenario, the cold front will approach the area by Friday, bringing cloudy skies with rain and thunderstorms. This cold front will move offshore by Saturday, keeping Earl away from the US, with a trough bringing drier conditions and slightly below average temperatures to the area for the weekend, with high temperatures likely in the upper 70s to lower 80s.

The other scenario, however, would happen should Earl start to recurve further west than currently expected, with a further west cold front. No model has showed this scenario yet, but some models have been trending south/west, and if this scenario is shown, then Earl may directly affect parts of the East Coast, leading to a completely pattern for the late week and weekend. Stay tuned for more details on Earl and whether it may affect the area or not.


Tropics: Atlantic Becoming Increasinly Active


Danielle: Now A Category 4 Hurricane

Last night, Daniell has intensified much more than expected, and has reached category 4 status. Danielle is currently southeast of Bermuda, and despite having briefly taken a west track early today, Danielle has resumed its NNW track, and will weaken and recurve out to sea well east of Bermuda. Danielle will still have some impact on the area, as swells are expected for the coast during the weekend, mainly on Sunday.

Tropical Storm Earl: Soon-To-Be Hurricane

Tropical Storm Earl has failed to significantly intensify, and remains a weak tropical storm as expected. Intensification will continue to be slow for the short term, but in the longer range, faster intensification of Earl is likely, and at this time Earl is expected to become a hurricane by Sunday or Monday, and a major hurricane by the middle of next week.

Earl continues to trend west on the models, and I did take this into consideration when making my forecast track, which is southwest of the model consensus. I expect Earl to continue moving WNW, then switching more NW towards the middle of next week. More details about Earl's longer range and how it may affect the area have been discussed above, in the late week section.

97L, Future Fiona

97L continues to slowly organize itself, and NHC is now giving 97L a 70% chance of becoming a TD over the next 48 hours. 97L has a favorable environment ahead of it, and will gradually intensify to become a tropical depression, then a tropical storm. For the longer range, Fiona may also become a hurricane as the models are suggesting.

Thursday, August 26, 2010

August 26, 2010: 5-Day Heat Wave Starts Sunday

Yesterday was the last of the cloudy and chilly days for a while, as high temperatures were only in the upper 60s to lower 70s. A coastal low brought heavy rain from Cape Cod through Boston and into Maine, however a small area of heavy rain also affected western Long Island and places further west, with rainfall amounts as much as locally over an inch of rain.

The rain is now over across most of the area, with partly sunny skies expected for today with comfortable temperatures. Enjoy these conditions while they last, as what could be the last heat wave of the summer will start on Sunday, and will not be a short lasting one.

Tomorrow's Outlook:

Tomorrow will be mainly sunny with a NW wind expected. High temperatures will rise into the upper 70s to lower 80s across the area, with the warmest temperatures in the immediate NYC area (NE NJ, Rockland/Westchester counties, NYC, western Long Island).

Long Lasting Heat Wave Starts Sunday

Saturday will be a nice day with mainly sunny skies, warming temperatures and a north wind. High temperatures will reach the mid 80s for the immediate NYC area, and the lower 80s for the rest of the area. This will be the last of these days for now, however, as temperatures will not be this low again until late next week.

With a high pressure near the area, a warm air mass will spread in from the west, with 850 mb temperatures climbing towards the 18-22c range. With the high pressure in place, sunny skies and dry conditions will persist until Wednesday or Thursday. These factors will allow for a 5-day widespread heat wave from the Mid Atlantic to the Ohio Valley.

Sunday will already warm up into the lower 90s for the immediate NYC area, with more widespread 90s on Monday, when high temperatures should reach the mid 90s for the immediate NYC area and the upper 80s to lower 90s for most of the area. Tuesday may be slightly cooler as the warmest 850 mb temperatures will stay to our west, with Wednesday potentially slightly warmer as these 850 mb temperatures spread into the area, with the GFS model showing mid to upper 90s for the immediate NYC area.

Relief Comes In The Late Week

Thursday will also be hot, however there could be more cloud cover as the next cold front is expected to approach. There is some uncertainty with the timing, however at this time a cold front is likely to reach the area by the late week, which should likely bring rain and cooler temperatures to the area.

We may have to keep an eye on the tropics as Tropical Storm Earl should be more south/west than Danielle, though should the latest models verify, Earl is unlikely to directly affect the area, with Bermuda having the greatest risk of seeing a direct hit from Earl (more details on that are below). Should Earl affect the area, the cold front would have to slow down and Earl would have to be far west enough to reach the East Coast with the cold front still to its west, which at this time only the 12z GFS showed. Stay tuned for more details in case the scenario for the late week changes.


Tropics: Danielle, Earl, And Potential Fiona


Hurricane Danielle:

Hurricane Danielle is currently a category 2 hurricane, with sustained winds at 105 mph and the low pressure at 970 mb. Earlier today, Danielle has developed an eye, which it has not done so previously, and despite being not too organized, Danielle is strengthening, and will likely become a major hurricane within the next day. As I mentioned in the last few days, the scenario where Danielle hits the East Coast were very unlikely, and the models now backed off from this solution, all of them keeping Danielle east of Bermuda.

Tropical Storm Earl:

Tropical Storm Earl is currently at 45 mph, with the low pressure near 1004 mb. Earl is moving west at this time. Earl should slowly intensify at first, as it is surrounded by dry air at this time, but its environment will gradually become more favorable, and by the weekend, Earl will be able to intensify into a hurricane, with a major hurricane also a good possibility should Earl not suddenly weaken like Danielle has done several times when she was expected to continue intensifying.

For Earl's track, it will be south/west of Danielle, but the question is whether Earl affects the East Coast or not. There will be a cold front approaching from its west, though if Earl recurves further east, it will stay out to sea. If Earl recurves further west, however, and the cold front is still to its west with supportive timing, then Earl may try to move up the East Coast. More details on this will come over the next few days.

Invest 97L:

Invest 97L has just recently formed south of the Cape Verde islands, and the NHC is giving 97L a 20% chance of becoming a tropical cyclone over the next 48 hours. 97L should continue moving west, and while it will take some time, 97L is likely to eventually become Tropical Depression 8, and later on Tropical Storm Fiona.

Tuesday, August 24, 2010

August 24, 2010: Heat Wave Possible Next Week

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

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Today was another cloudy and chilly day for the area, with high temperatures in the upper 60s to lower 70s, below the average high temperatures again. These cooler than normal conditions should last through Friday, though Thursday should be warmer with temperatures near average. Enjoy these chilly conditions while they last, however, as what may be our last heat wave of the summer will start by the end of the weekend.

Tomorrow's Outlook:

Tomorrow will be another cloudy and chilly day across the area, with a north wind expected. High temperatures will be in the lower to mid 70s for most of the area, slightly cooler in places that see locally heavier showers.

As mentioned yesterday, a low pressure will stay to our east, and the models backed off from the widespread heavy rain solution for the area. Scattered showers are expected, with the best chance for this in the eastern parts of the area, with the heaviest rain in southern Maine, where locally heavy rain is possible.

Thursday - Saturday: Comfortable, Becoming Drier

Thursday will be warmer, with high temperatures likely to return into the lower to mid 80s for parts of the area, ahead of the colder air mass that will approach the area. An isolated shower or two is possible, but the best chance for that will stay to the north of New York City. As the skies clear and the colder air mass spreads in, Thursday night will be much colder, with lows in the 50s for most of the area, and a few upper 40s are possible. Check the 5-Day Forecast for the expected low temperatures in each part of the area.

Friday will be another chilly day, with high temperatures in the mid 70s to lower 80s across the area, but what will be noticeably different will be the return of sunshine. Mainly sunny skies are expected on Friday with dry conditions, which should persist into the longer range. Friday night's lows will be similar to those of Thursday night, if not slightly colder.

Saturday will be slightly warmer, with high temperatures back into the lower to mid 80s, which will only be the start of the next warm up.

Sunday - Tuesday: Last Heat Wave Of The Summer?

While according to the calendar, summer is almost over, the last few months have been unusually hot, and summer is not planning on leaving without one last round of warmth, with what could potentially be one of our last, if not our last heat waves of the summer.

A high pressure will build into the area, keeping the sunny and dry conditions around, while a warmer air mass spreads in from our west. 850 mb temperatures will approach 20c, leading to high temperatures rising into the lower 90s for parts of the area starting on Sunday. While the models are not showing temperatures reaching the mid 90s at this time, this potential will be watched in case the models trend warmer.

This warm up will not be short lived, as the high pressure is expected to stick around for a while. What may bring down the heat, though, is a weak cold front that could move through New England on Tuesday. This cold front should cool things down towards New England, and it may also slightly cool the area down, but it is unlikely to end the stretch of above average temperatures, which should last well into next week. Stay tuned for more details on this potential heat wave over the next few days.

Hurricane Danielle: Now A Tropical Storm, But Expected To Strengthen

After Danielle briefly became a category 2 hurricane last night, Danielle unexpectedly weakened, and with the help of dry air, is now back to a tropical storm. This is only temporary, however, as Danielle is showing signs of organization, and may become a hurricane as early as tonight or tomorrow morning. The environment ahead of it is still supportive of intensification, and a category 2 hurricane is possible again, with a major hurricane not out of the question.

The latest models have trended west with Danielle's track, now taking it just near Bermuda. While this westward trend is evident, trends also have limits, and this limit appears to be the high pressure over the East Coast that will also lead to a heat wave in the Mid Atlantic. This high pressure will slowly move towards West Virginia during the early week, but it will likely be strong enough to prevent Danielle from moving NW and affecting the Northeastern US. As a result, Danielle will then be forced to turn north, then northeast and out to sea.

The latest GFS run, though, does something completely different, significantly weakening the high pressure and allowing Danielle to make almost a direct hit near the area. This solution is very unlikely at this time though, considering that the long range GFS usually lacks consistency in storm tracks, and that it goes against the model and forecast consensus that has been showing a high pressure not too far to our SW for the last few days, but this solution will still be watched, as this is still in the longer range and nothing is certain yet.

Invest 96L: Elsewhere in the tropics, Invest 96L in the eastern Atlantic Ocean is likely to form into a tropical depression, however its envionment is not too supportive, with 96L surrounded by a lot of dry air. Any intensification of 96L over the next few days is likely to be slow.

Monday, August 23, 2010

August 23: Post Storm Review, Look At Week Ahead

Today's update was put in two parts, both in this post. The first part of this post is about yesterday's storm and looking at the forecast for it, and the second half is the discussion about this week and the weekend, as well as Tropical Storm Danielle. I also added a poll to the right below the radar about what next week could bring to the area, for those who want to vote.

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Yesterday's storm is mainly over for the area, though there are still scattered showers around, mainly northwest of New York City. Looking at the radar estimates, heavy rain did fall across most of the area, with over 1.5 inch for most of the area, except for Long Island. The heaviest rain totals in the area ended up over northwestern Bergen County, NJ, into Rockland County, NY, where rainfall amounts were as high as 5 inches. Long Island, however, ended up with the lowest totals, with rain amounts generally between 1/2 and 1 inch, locally higher towards western Long Island.

Post Storm Review: What Happened?

Yesterday's storm was one of the most difficult storms of the year to forecast. Even up until the day of the storm, there was a lot of uncertainty, with the models showing a wide range of solutions up to the last minute. There were some things that were likely to happen, such as the heaviest rain focusing in central New York as well as heavy rain falling in the area, but there also was a lot of uncertainty, such as where the secondary low pressure tracks, the location of the heavy rain axis for the area, and whether the heavy rain offshore would move inland as the models suggested to bring southern New England a round of heavy rain, which did not happen.

Below, I posted a comparison of my forecast rain totals and a rough estimate of the actual rain totals, looking at the radar estimates. The estimated rain totals could be slightly off for some places, but they give an idea of how much rain fell.




What was right: The map did get some parts correct, such as the heavy rain staying south/west of Boston, and SW Maine only seeing light rain, which was a difficult decision to make based on the models. For example, one run of the NAM model showed barely an inch of rain for Boston and a little rain in SW Maine, and the next run showed nearly 5 inches of rain in Boston and over 2 inches in SW Maine. The 1 inch line that ran through northern New Jersey verified, as most places south of that line saw less than 1 inch, though most of Long Island saw less than 1 inch. The forecast for the 2+ inches area to mainly stay N and NW of NYC was also correct.

What went wrong: The rain was lighter across PA and central/southern NJ than expected. I noticed that by the early afternoon hours, when there were only scattered storms around and it appeared that due to the clouds clearing in Pennsylvania behind the strong storms, there wouldn't be heavy rain overnight (behind the storm line, that was supposed to move through during the evening) for PA and parts of New Jersey.

The forecast for Long Island also did not verify. The models suggested that heavy rain would form offshore and move inland overnight, bringing a round of heavy rain. The heavy rain did form, but instead it went out to sea, which I noted as a possibility in the storm scenario update I posted yesterday afternoon. While it also appeared that Boston wouldn't see very heavy rain, they still saw much less rain than expected, as most of the rain bands were unable to reach them, and instead dumped heavy rain in other parts of Massachusetts and Rhode Island. Northeastern NJ and SE NY also ended up with more rain than expected.

Summary: This was a very difficult storm to forecast, and there were a lot of parts that I missed in my forecast, but there were also some parts that I got right as well. It did become apparent that some parts of the forecast would be incorrect several hours before they happened, showing that making last minute forecasts based on the observations is important in cases where there is uncertainty up to the last minute.


Today's Update: Cloudy And Chilly Week, But Warmth To Return


The rest of today will be cloudy and chilly with isolated showers, locally heavy, with a NE wind. There could be gusty winds in Long Island and near the coast. High temperatures will be in the upper 60s to lower 70s inland, lower to potentially mid 70s for the immediate NYC area, and in the upper 60s to lower 70s for Long Island and S CT.

Tonight will be cloudy, with low temperatures in the lower to mid 60s for S CT, mid to upper 60s for Long Island, in the lower to mid 60s for the immediate NYC area, and in the upper 50s inland. Tomorrow will be another cloudy and chilly day, with high temperatures similar to, if not slightly warmer than today's, with an ENE wind expected. Windy conditions are possible along the coast again.

A low pressure will pass to our east on Wednesday, however it will keep the cloudy and chilly conditions around, along with some showers. This low pressure will bring steady light to moderate rain for eastern New England, with the highest rain totals in Maine, but these totals won't be as big as they were with yesterday's storms.

Some models keep the low pressure close to the area and bring a widespread 1 to 2 inches of rain for the area, and while this is unlikely at this time, this solution will be watched in case it becomes likely.

Longer Range Outlook: Cooler Weekend, Heat Could Return Afterwards

By Thursday, a colder air mass will approach the area, though temperatures will be warmer, with high temperatures in the lower to potentially mid 80s ahead of the colder temperatures. By Friday, though, the cold air mass will be over the area, with much cooler temperatures. High temperatures will likely be in the lower to upper 70s across the area, with low temperatures in the 50s for most of the area, except for the immediate coast. The interior areas may potentially reach the upper 40s.

Starting Sunday or Monday, however, the models are showing a high pressure near the area, which will also block Danielle from affecting the East Coast (more details on Danielle are below), and this is expected to bring a much warmer air mass into the area. There is uncertainty on how warm the air mass is, but there is the potential for temperatures to reach the 90s again for parts of the area.

I added a poll in the top right corner of the website below the radar about next week, about whether next week could feature temperatures below, near or above average temperatures, or a heat wave. Vote your thoughts on next week in the poll, which will close on Friday. More details on this will be posted tomorrow, as well as a detailed discussion on Danielle.

Hurricane Danielle: Potential Major Hurricane To Stay Offshore

Tropical Storm Danielle is currently a strong tropical storm in the eastern Atlantic Ocean, and is moving WNW. Danielle is currently located under a favorable environment, and is expected to strengthen into a hurricane within the next 12 hours. Afterwards, there is uncertainty on how favorable its environment is, but if it can stay under supportive conditions, it may strengthen into a category 3 major hurricane. A category 4 hurricane is unlikely at this time but is not out of the possibilities.

Danielle, however, is unlikely to affect the East Coast. In a few days, while there is a trough near the area, there will be two high pressures, one near Bermuda and one in the east central Atlantic, which will allow Danielle to move in between. This will also force Danielle to turn more NW, and a high pressure near the area by early next week will block Danielle from approaching the area, forcing it to turn north and then NE. It may threaten Newfoundland in Canada, otherwise it should stay away from land.

A more detailed discussion on Danielle, as well as a map, will be posted tomorrow.

Sunday, August 22, 2010

August 22 Storm Updates

Below, I will post short term storm updates for the heavy rain event that will affect the area. As there is still uncertainty, I will also include updates on the latest storm scenario, as well as any potential change from the original forecast.

Note: ***The short term forecast maps will be posted to the right of most of the storm updates. Click on these maps to view them in a larger size.***

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Storm Updates:

4:30 PM: There is currently widespread moderate rain in western CT, moving NE. Eastern CT will likely stay away from this area of rain. Locally heavy storms are currently in Bergen county, with the northern end of a line of locally strong thunderstorms expected to pass through NE NJ and NYC later this afternoon. There is also a large area of heavy rain offshore, which could affect Long Island later today.

This is the final update for today. The next update will be posted tomorrow in the early morning hours. To see more about the current storm scenario and what might happen tonight, read the section in the bottom of this post.


2:47 PM: A heavy thunderstorm is currently in northeastern New Jersey, and is producing very heavy rainfall, with up to an inch possible in up to 1/2 hour. Flash flooding is possible with this storm, as well as strong wind gusts. This storm is moving northeast, and will enter Rockland/Westchester counties in NY and may affect far SW CT.



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Storm Scenario Updates:

4:30 PM: The low pressure is now intensifying offshore, currently located SE of New Jersey, however this low pressure so far is SE than what the models showed it, with the models showing it just east of central New Jersey. There is still some uncertainty, and the low pressure could switch direction and move more north than NE, but at this rate, most of the heavy rain tonight will stay east of NYC, with a lot of places west of NYC possibly staying mainly dry for tonight with only a little rain instead of seeing another round of heavy rain. If the heavy rain will move into Long Island and S CT, 2 to 3 inches of rain are possible there, though the western parts of the area could end up with a rain total not much higher than their current total at this rate.

August 22 Final Storm Forecast

Over the last few days, I have mentioned that a heavy rain event is possible for Sunday night and Monday, and while it was certain that heavy rain would fall in central New York, it was uncertain if the heavy rain would extend into the area or if it would stay to our north. The models did not have a good handle of this storm, ranging from as little as no rain in NYC on the short term NMM model to as much as nearly 4 inches of rain on yesterday's GGEM run. The models yesterday started showing a secondary low pressure enhancing the rain over the area, and this scenario now seems likely, however it is uncertain where the low pressure forms and where the heaviest rain falls.

Below is my storm discussion and final forecast map. Note that as it is still uncertain where the heaviest rain falls, some slight revisions to the forecasts could be made during the storm updates that I will post this afternoon.

Storm Final Forecast / Rain Map

Click on the map to view it in a larger size.
Storm Set Up: What we are currently seeing is a low pressure located on the border of NW PA and SW NY, with its cold front currently near west Pennsylvania, and a weak low pressure is forming near northeastern North Carolina. The low pressure in NW PA will continue to move ENE, and once it reaches central New York, which should be around 2 PM, the low pressure will start to transfer its energy to a developing low pressure SE of NYC, with heavy rain forming near and east of the immediate NYC metro. This low pressure is then expected to weaken throughout Tuesday while another low pressure forms to its south, staying well east of the area while moving NNE towards Nova Scotia, which for the longer range, will help draw in a chilly air mass into the area on Friday.

Precipitation Forecast: With the low pressure moving into central New York, the heaviest rainfall will be located until this afternoon towards south/central New York, and south of the storm, non-severe showers and thunderstorms, locally heavy, will affect the area during the afternoon into the evening hours. With this part of the storm, at least 1/2 to 1 inch of rain is likely for most of the area, with locally higher amounts up to 1.5 inches in the heavier showers.

As the secondary low pressure takes over, the heavy rain will end across central/northeastern New York, with heavy rain forming near the low pressure. It is still uncertain where the low pressure will be exactly located, with the storm's heavy rain forming either near the immediate NYC area, over Long Island and Connecticut, or offshore. The rain will then gradually become lighter in the western parts of the area overnight, with light rain for Monday, while Long Island and S CT will likely continue to see moderate to heavy rain.

Forecast Rain Totals / Rain Map: At this time, at least a total of 1 to 2 inches is possible for most of the area, with 2-3 inches for Long Island/S CT and places well north of NYC. These rain totals will possibly change, stay tuned for more updates this afternoon and/or in the late morning in case the storm's forecast changes.

Note: This rain map has an unusually low confidence level, due to an unusually large model spread, and it is possible that the scenario may end up being different from what this map shows.


Other Notes: Tropical Depression 6 has formed in the eastern Atlantic Ocean last night, and more details on that, as well as the longer range and the cooler temperatures that will return to the area by Friday, will be posted with the next full update tomorrow in the early morning.

August 22 Early Morning: Rain Entering

4:50 AM: What will likely be the first widespread heavy rain event for the area in over a month is starting now, with an intensifying band of heavy rain and a few rumbles of thunder affecting NYC, northern New Jersey and SE NY. For the short term, the heaviest rain will be located towards Sussex, NJ and Orange, NY counties where heavy rain is expected, with moderate to locally heavy rain for NE NJ, Rockland and Westchester counties in NY, and NYC. Lighter rain will fall in Long Island and S CT counties.

The weather models, however, failed to forecast this heavy rain band for the morning hours, most of them keeping the morning hours dry. Most of this storm's future is still uncertain, and will depend on short range observations.

Rainfall amounts up to 8 AM in most of Sussex and Orange counties will range from 1 to 2 inches of rain, with up to 1/2 inch for the immediate NYC area, and up to 1/4 inch for Long Island and S CT.

A final forecast and discussion for this storm will be posted this morning, along with a rain map, and storm updates will be posted this afternoon and early tomorrow morning if needed.

Saturday, August 21, 2010

August 21: Rain Returns Tomorrow Night

Yesterday was mainly sunny across the area, with high temperatures in the mid 80s inland, with upper 80s to lower 90s for the immediate NYC area. As of 4 AM, with a chilly air mass currently over the area, temperatures are dropping quickly, and for this morning, are expected to reach the upper 40s to lower 50s inland, mid to upper 50s north and west of NYC, and in the mid 60s for New York City. Temperatures will also reach the upper 50s to lower 60s for Long Island, and the lower to mid 50s for southern Connecticut.

The area is still expected to be dry today, however this won't last for long, as a storm approaching the area will bring another chance of rain for Sunday night and Monday.

Today's Outlook:

Today (Saturday) will be a nice day across the area with partly cloudy skies expected and an onshore SE wind. High temperatures will reach the lower 80s inland, mid 80s for the immediate NYC area, and the upper 70s to lower 80s for Long Island and S CT.

Most of the region will also stay dry today, with the exception of western Pennsylvania and New York where a few showers and thunderstorms are possible, but this rain will continue to spread east overnight, reaching the area by Sunday.

Sunday And Monday: Rain, Potentially Heavy

Since my last update, the models were consistent in showing the heavy rain towards northern New England and southern Canada, however south of that area, there is still a lot of uncertainty, with some models such as the GFS only showing 1/4 inch, the NAM showing 3/4 inch, and the GGEM is showing nearly 2 inches for a large part of the area, though the GGEM is likely an outlier.

The models agree on a line of moderate to locally heavy rain moving through between Sunday late afternoon and Monday early morning, with rainfall amounts likely to be in the range of 1/4 to 3/4 inch across the area, the highest amounts towards the northern parts of the area. Precipitable water values are over 2 inches, and this should lead to locally heavy rainfall, with amounts locally up to 1.25 inch. These amounts may still change though, and an afternoon update may be posted to update these rainfall amounts.

Afterwards, the models have significant differences, with the GGEM forming a low pressure to our southeast with another round of heavy rain, the NAM stalls the heavy rain to our east while forming a low pressure off the SE coast, which would likely continue to move up the coast and bring a round of heavy rain to the eastern parts of the area, and the GFS simply moves the storm offshore with no additional development, though the GFS is not very good in its longer range. There is support from several models for the second low pressure offshore, however, and this scenario needs to be watched. Stay tuned for more details on this potential.

The next update that will be posted, either this afternoon or tomorrow morning, will include more details about this storm and the longer range beyond this storm.

Thursday, August 19, 2010

Early August 19: Rain Possible Sunday, Will It Happen?

Note: I was unable to make this post yesterday afternoon, but I was able to work on it now. Until early September, the posting schedule will work differently, with some days having the daily update posted in the afternoon, some in the early morning, and there could be a few days with no updates at all.

The 5-Day Forecast page will occasionally be updated, as well as the "Severe Weather/Tropics" page, but whether they are updated or not, the overall conditions and forecast temperatures for the next 5 days will still be mentioned in the discussion.

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Yesterday was a cloudy day across the area, and as expected, the rain stayed to the south of New York City. As I mentioned in my first forecast for this storm, it was unlikely to trend too much north, if at all, due to its relatively small size and the position of the cold front, but what was unexpected was the big south trend, which combined with a high pressure to our north, suppressed the storm and kept most of the area dry with an isolated shower or two. Even when I made my rain map yesterday, there were still a few models bringing moderate to heavy rain to New York City, however that scenario was unlikely given the set up.

Meanwhile, the models are now showing another heavy rain potential for Sunday and Monday. Looking at the summer pattern so far, however, it is questionable if there will be heavy rain in the area, with more details on this potential below.

Today's Outlook:

Today (Thursday) will be partly sunny with a NE wind this morning turning south by the afternoon. High temperatures will be in the lower to mid 80s inland, mid to upper 80s for the immediate NYC area, and in the lower to mid 80s for Long Island and southern Connecticut.

Looking at the region, the Northeast will be chilly, with highs in the 70s to lower 80s, but the southern Mid Atlantic, will not be as hot with highs in the lower to mid, locally upper 80s due to the cloud cover and storms. A few isolated showers are possible for the Northeast, with the NYC area expected to be dry, but the best chance of rain will be in central and southern Virgina, where there is also the chance of a locally strong or severe thunderstorm.

Friday And Saturday: Warming Up, Then Cooling Down

A weak cold front will move through on Friday, however it will be a dry cold front, with only a slight chance of rain to the north of the New York City area. Behind this cold front, a cooler air mass is likely, but it will not immediately come in, leading to warm temperatures on Friday with a west to NW wind expected. High temperatures will reach the mid to potentially upper 80s inland, upper 80s for the immediate NYC area, and the mid to upper 80s for Long Island and S CT.

Saturday, however, will be cooler as an onshore SE wind is expected to return. High temperatures will reach the upper 70s to lower 80s for Long Island and S CT, and the lower to mid 80s for the interior and the immediate NYC area. Meanwhile, a disturbance well to our north and west will approach the Northeast, which should bring cloudy and potentially wet conditions for Sunday and Monday.

Sunday And Monday: Rain Potential, But Will It Happen?

For Sunday and Monday, a disturbance that will stay to our north will move through the region, bringing a heavy rain potential to the Northeast. With the clouds in place, and an ESE wind expected to continue, high temperatures will stay on the chilly side, in the lower to mid 80s across most of the area. The real question, however, is where the heavy rain will fall.

The last few heavy rain potentials did not verify for the area, the first one bringing only locally heavy rain for the immediate NYC area, and yesterday's storm staying well to our south. The disturbance is also staying to our north, with the models showing most of the heavy rain to our north and west. Looking at these factors, it is questionable if there will actually be heavy rain for the New York City area. While it is too early to know for sure, it is possible that the heavy rain will stay to our north and northwest, but it is also possible that the heavy rain could affect the area. Stay tuned for more details.

Wednesday, August 18, 2010

August 18 Morning: Final Storm Forecast

The storm that will affect the Mid Atlantic through tomorrow was a very difficult one to forecast, with models constantly switching solutions. What was very likely from the start though was that the storm would not trend much north, if at all due to the placement of the stalled front. Instead, however, the storm trended significantly to the south, which was not expected.

The models are now coming to an agreement, and looking at most of the models, northwestern New Jersey and Orange County, NY are likely to stay dry, with the immediate NYC area also likely to stay dry though a few showers are possible, with any rainfall less than 0.1 inch. Southern Connecticut is also likely to stay mainly dry with a few showers possible, especally in SE CT, and with the sharp cutoff line to the SE of Long Island, between 1/4 and 1/2 inch of rain is likely in Long Island, with the highest amounts of over 2 inches of rain to the south of the area, towards the Delmarva.

Below is my rain map for this storm. Note that there is still some last minute uncertainty and the heavy rain and northern end of the rain could end up slightly further north or south than what the map shows. Another update will likely be posted later today, focusing on the longer range.

Tuesday, August 17, 2010

August 17: Wednesday Night Storm Update

Today was yet another hot day, with high temperatures ranging from the mid 80s inland to the lower 90s in the immediate NYC area. Yesterday's storms ended up being very heavy rain makers in the Jersey City, NJ area, with radar estimates showing as much as 3 inches of rain in a few areas. Another severe thunderstorm moved through northeastern New Jersey and Rockland County, leading to very heavy rainfall, gusty winds and some small hail. Despite this, however, the severe weather coverage area was not as widespread as expected, and the storms also weren't as intense despite the favorable parameters, with low 700 mb relative humidity a possible cause.

Despite the locally heavy rainfall, most of the area only ended up with light rain at best, with monthly rainfall still well below average. With Thursday's heaviest rains staying to the south of the area, and a consistently wet pattern unlikely to set up in the near future, the drought is expected to persist.

Wednesday - Thursday Storm Forecast Update:

Tomorrow will have mostly cloudy skies with showers becoming more likely for the late afternoon hours across the area. The storm, however, has trended much further south than it was yesterday, and while a north trend is expected, it is unlikely to reach the scenario that the models showed yesterday, with a widespread 1 to 3 inches of rain for the area.

Looking at the latest models as well as my thoughts of potential trends, the northwestern areas are likely to stay north and west of the cutoff line of the heavy rain, with near or a little over 1/4 inch possible. Up to 1/2 inch is possible in the wetter scenario. For the immediate NYC area, 1/4 to 1/2 inch of rain is likely, with up to 3/4 or 1 inch in the wetter scenario. Some models are showing a very sharp cutoff line for the immediate NYC area, with only less than 0.1 inch NW of NYC, and up to 1 inch SE of NYC, and at this time I am expecting a cutoff line not as sharp as these models are showing, and slightly further north than they are showing. For Long Island and S CT, 3/4 to 1.5 inch of rain are likely, with as much as 2 or locally more inches in the wetter scenario. This is also a very uncertain area, as some models have the sharp cut off line just north or just south of Long Island.

This storm is still very uncertain, and the next few model runs may help give a better idea of the expected scenario. A rain map will be posted tomorrow for this storm, as well as an update focusing on the longer range.

Monday, August 16, 2010

August 16 Storm Updates

5:00 PM: Since the morning update that was posted, it became apparent that the set up would not be able to produce a severe weather outbreak for the area as was originally expected. Despite favorable parameters, storms have failed to form and intensify, and instead have weakened or dissipated in several places, including near Wahington DC and northeastern PA, with a storm that was moving towards NYC but instead fell apart. This is not a good sign for severe weather, and as a result, I have removed the 30% wind risk. I have kept a 15% wind risk for now, as the parameters remain favorable and isolated severe storms are around, however widespread strong to severe thunderstorms are not expected.

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6:15 PM: This is the last storm update posted for today. The next update will probably be posted tomorrow (Tuesday) afternoon. For the latest potential rainfall amounts for Wednesday night's heavy rain, please look at the 5-Day Forecast (the 5-day graphic was not updated today, and there is no Day 5 forecast, though there should be one tomorrow).


6:10 PM: The latest short term update for the two severe thunderstorms affecting the immediate New York City area has been posted to the right. Click on the image to view it in a larger size.



5:50 PM: WARNING: A rapidly forming severe thunderstorm has just formed south of the Bergen County strong thunderstorm. This storm is capable of producing moderate hail, damaging wind gusts and heavy rainfall, and will be moving through Jersey City and south/central Manhattan over the next 1/2 hour.


5:42 PM: A strong thunderstorm is currently approaching Bergen County, producing heavy rainfall, strong wind gusts, and small hail. This thunderstorm will then approach southern Westchester county, and SW Connecticut. A short term outlook has been posted to the right, click on the map to view in a larger size.



5:02 PM: There are several strong thunderstorms in the area. One strong thunderstorm is approaching JFK near Coney Island moving east. This storm will affect the southern coast of SW and potentially south central Long Island with heavy rainfall, gusty winds and potentially small hail. A severe thunderstorm is in southern Middlesex County moving ESE, which will affect Monmouth county, outside of the forecast area. Another strong storm is in southern Morris county, moving NE, and will affect Essex, SE Passaic, and central Bergen counties with heavy rainfall, gusty winds and potentially small hail.

Aug 16 Morning: Today's Storms, Late Week, Tropics

Posting For Today And Tomorrow: This morning update includes my latest forecast for today's strong to severe thunderstorms, an update on Thursday's potential heavy rain event, and a brief update on the tropics, with the remnants of Tropical Depression 5 likely to regenerate today or tomorrow. Storm updates will be posted between 4-6 PM today if needed, otherwise the next update will be posted tomorrow afternoon.

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Today's Severe Weather Potential: 15% Risk

The cold front is currently approaching the area from the west, with thunderstorms starting to form in Pennsylvania. These storms will continue to develop and intensify while moving east. The parameters are favorable, with CAPE between 1500 and 2500, bulk shear up to 40 knots, and lapse rates up to 6.5. The cloud cover is not very supportive, which may limit the severe weather risk and prevent the 30% wind risk from verifying, though with the parameters in place, a severe weather outbreak is likely for the western and central parts of the area as a squall line moves through later this evening.


Storms today will be capable of producing damaging wind gusts and heavy rainfall. Hail is also possible in the northern parts of the area, along with an isolated tornado also possible. If needed, storm updates will be posted between 4 and 6 PM. There may also be an updated version of the map, if necessary.






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Thursday's Storm: Too Far South?

Yesterday's update mentioned a possible storm that the models are now showing on Thursday, with heavy rainfall amounts likely for places that are affected by this storm. The latest models, however, trended much further south with the heavy rain zone, and while they may trend slightly further north, a significant north trend is unlikely.

With the cold front stalled to our east, a low pressure will move up the cold front, however it is uncertain how far to our south and east the cold front will be when the low pressure moves over it. As the cold front isn't likely to trend much further north, as it should be to our east, the storm won't trend too much north/west, likely leaving the western parts of the area drier than the rest of the area. Despite this, with a north trend still possible, a heavy rain event is expected for parts of, if not most of the area, with Long Island and S CT the most likely places to see heavy rain, with 2 to 3 inches of rain a good possibility. Stay tuned for more details later this afternoon and tomorrow afternoon.




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Brief Tropics Update: Tropical Depression 5's remnants are currently in the Gulf of Mexico, and are likely to regenerate over the next day or two. The storm will then move over the warm waters of the northern Gulf of Mexico and will likely intensify to a strong Tropical Depression.

Sunday, August 15, 2010

August 15: Storms Tomorrow, Heavy Rain Thursday

Today has been another chilly day, but this time there are also cloudy skies, along with light to moderate rain that is still affecting the area. This rain is generally light and has no thunder, however tomorrow will be the complete opposite of tomorrow, with hot and humid conditions as well as the potential for strong to severe thunderstorms.

Tomorrow's Outlook:

Tomorrow is likely to start out mainly cloudy with an isolated shower or two possible at first. By the early or late morning hours, though, the cloud cover is likely to start clearing, with partly cloudy skies expected for the afternoon. This, combined with a warm air mass, will allow temperatures to quickly warm up, reaching the upper 80s to lower 90s for the immediate NYC area, and mid to potentially upper 80s for Long Island and S CT. Humid conditions are also expected tomorrow with dew points in the 70s, which will lead to the heat index reaching the mid 90s for the immediate NYC area.

A cold front will also approach the area, and is expected to move through tomorrow night before stalling just to our east. The models remained rather consistent since yesterday, with a severe thunderstorm outbreak likely for tomorrow afternoon and evening.

Tomorrow's Severe Weather Risk: 15% Risk

As the cold front approaches the area, instability is expected, with supportive parameters, including CAPE up to 2000, Lapse Rates up to 6.0, and bulk shear up to 40 knots. At this time, there is a 15% risk of severe weather in place, however an upgrade to a 30% wind risk is possible with tomorrow's morning update, which will include severe weather risk maps. Storms are expected to start affecting the area during the afternoon hours and last through the early overnight hours, with the main threat being heavy rainfall and strong wind gusts. Small hail an an isolated tornado are also possible.

As we have seen with the last severe weather outbreak, the exact impact area as well as places that get shafted from the storms usually cannot be determined until the day itself, when most short range models and the observations are more useful. It is still possible that the risk could change with tomorrow's morning update.

Tuesday - Friday: Dry Start, Wet End

Tuesday and Wednesday are expected to be dry, but warm temperatures are expected. High temperatures will reach the upper 80s to lower 90s for the immediate NYC area for Tuesday, and the mid to upper 80s on Wednesday. As the cold front will have stalled nearby, however, a low pressure is expected to form to our west and approach the area, bringing a potentially wet Wednesday night and Thursday.

Precipitable water values will again approach 2 inches, and with the low pressure likely to stay nearby, a chilly and wet Thursday morning is likely at this time. There is still uncertainty, however, as the models are not consistent on a solution yet, and the heavy rain area, which is currently over our area, may still change its place several times before the models reach a solution. Stay tuned for more details on this potential.

August 15 Update: Light To Moderate Rain

3:25 PM Update: An area of light to moderate rain is approaching the New York City tri-state area. The heaviest rain is falling with a line currently in western NJ and SE PA, moving ENE. Most places should see at least light rain, however there are some areas of moderate, locally heavy rain in this line, one of them moving towards north central New Jersey. Rainfall amounts up to 0.2 inch are expected for most places, with amounts locally as high as 1/2 inch, especially with the area of rain moving into north central NJ.

The posting schedule will go a little differently over the next few days. A full update will be posted by 6 PM today, including details about tomorrow's severe weather potential, and heavy rainfall that is likely for Thursday. A final update on the severe weather potential will be posted tomorrow morning with a brief update on the longer range, with storm updates to be posted late tomorrow afternoon if needed.

Saturday, August 14, 2010

August 14: Severe Thunderstorm Possible Monday

Today was another comfortable day, as high temperatures were generally in the upper 70s to mid 80s. Over the next few days, however, conditions will become more uncomfortable with increasing humidity and rain returning, with a recent trend in the models now introducing a severe weather outbreak possibility for Monday.

Tomorrow's Outlook:

Tomorrow will be partly cloudy, with increasing cloud cover throughout the day. Despite an onshore SE wind expected again, high temperatures will be slightly warmer, in the lower to mid 80s inland, mid 80s for the immediate NYC area, and in the upper 70s to lower 80s for Long Island and S CT.

While most of the area will stay dry tomorrow, moderate to heavy thunderstorms are expected for most of PA and NY, with some storms reaching strong to severe levels. Some of these storms should reach the western parts of the area late tomorrow afternoon or evening, spreading into the rest of the area tomorrow night into Monday morning. Any storm that reaches the area will not be severe, but with precipitable water values near or over 2 inches, these storms could produce locally heavy rainfall.

Monday: Severe Storms Possible?

Up until now, the models were not supportive of any severe weather, with a lack of supportive parameters, along with cloudy skies, chilly temperatures and a SE wind. The latest model runs, however, took a significant trend that introduces a severe weather potential for Monday evening. The cold front will approach the area during Monday, with showers and thunderstorms, locally heavy, likely for the morning hours. Should the latest models verify, the sky will then clear for the afternoon, with temperatures rising into the upper 80s to lower 90s with hot and humid conditions, and thunderstorms will form in NY and PA, potentially reaching strong to severe levels while moving towards the area.

The parameters are supportive, with CAPE over 2000, LI up to -6, lapse rates between 6.0 and 6.5, and bulk shear between 30 to as much as 45 knots. Some factors that may limit severe weather chances are cloud cover and the relative humidity. Should the severe weather potential verify, a 30% severe weather risk may be possible, with damaging wind gusts the main threat, with heavy rainfall also possible due to high precipitable water values.

This is only a recent trend, and the models may not have finished trending yet, meaning that this solution can still change. More details will come on this potential tomorrow afternoon.

Longer Range: Uncertainty Continues

For the longer range, there is still a lot of uncertainty as the models are showing different solutions, however it is likely that Tuesday and Wednesday will be drier, despite a chance of a shower or storm, as the cold front moves to the east away from the area. Temperatures are likely to stay in the 80s during this time frame, and while the GFS shows more rain through next week, it is considered an outlier at this time as it has had several cases similar to this one where it showed widespread light rain in the longer range and backed away from the scenario towards the shorter range. The models do, however, agree on a chance of rain for Friday. More information will come on that once details become clearer.

Friday, August 13, 2010

August 13: Widespread Rain Returns Monday

Thursday ended up being a very chilly day, with high temperatures only in the 70s to lower 80s, with the western and central parts of the area seeing some light rain. The heaviest rain fell in northern New Jersey, where as much as 3/4 inch of rain fell. Today was also chilly, with similar high temperatures, but conditions were dry with more sunshine than yesterday.

Yesterday's rain was the first measurable rain for parts of the area since July, ending a 13-day stretch of dry weather. Parts of Long Island though have yet to see rain this month, with the last widespread rain event there being on July 29. The next rainfall there is expected on Monday, which would make this a 17-day stretch of dry weather.

Tomorrow's Outlook:

Tomorrow will be mostly sunny across the area with a SE wind expected. Due to this and a chilly air mass over the area, high temperatures will reach the lower 80s inland, lower to mid 80s for the immediate NYC area, and upper 70s to lower 80s for Long Island and S CT.

Dry conditions are expected again tomorrow, however these dry conditions won't last for long. Showers and thunderstorms will already approach the western parts of Pennsylvania and West Virginia, and will reach the area by Sunday night.

Sunday - Tuesday: Locally Heavy Rain

Sunday will continue with the SE onshore wind, however temperatures will become warmer, with high temperatures expected to reach the lower to mid 80s inland, mid 80s for the immediate NYC area, and the upper 70s to lower 80s for Long Island and S CT. Scattered showers and thunderstorms, locally heavy, are expected for the western parts of the area starting in the afternoon, spreading eastward through the overnight hours.

These storms are expected to affect the area between Monday and Tuesday. With a humid air mass and precipitable water values over 2 inches, locally heavy rainfall is expected. Most models have trended considerably drier for this time period, with the GFS model only showing 3/4 inch at most, however the GFS is not very reliable, as it has been too variable with this event over the last few days, and I am leaning towards the NAM, as it has performed better than the GFS for the last few events, and it also shows the possibility of locally heavy rainfall. At this time, I am expecting a general 1/4 to 3/4 inch for the area, with amounts locally as high as 1 to 2 inches of rain. Drier conditions are expected by Tuesday night. This will not be enough to end the drought, but it will prevent the drought from becoming worse for the short term.

For Wednesday, there is a lot of uncertainty as the models have significant differences with the rain, cold front location and the air mass. For now, I leaned towards a solution where an isolated shower or thunderstorm is possible with highs generally in the lower to mid 80s, though this is likely to change as details become clearer. More on the longer range will come tomorrow.

Wednesday, August 11, 2010

August 11: Stormy Pattern Next Week

Today ended up being another hot and humid day, with high temperatures in the upper 80s to lower 90s inland, and in the lower to mid 90s for the immediate NYC area. Today will be the last of these hot days for a while though, as temperatures cool down into the 80s and even upper 70s for the next few days, with temperatures staying in the 80s next week as a stormy pattern sets up along a stalled cold front.

Tomorrow's Outlook:

Tomorrow will be colder than today. With a cool air mass around, cloudy skies, and an onshore ESE wind, high temperatures will only rise into the lower 80s inland, lower to mid 80s for the immediate NYC area, and in the upper 70s to lower 80s for Long Island and S CT. Areas that see rain during the afternoon could be slightly cooler than the forecast temperatures.

Isolated showers and thunderstorms are also expected tomorrow. Most of the storms will stay to our west and south, in Pennsylvania and the central/southern Mid Atlantic, where heavy rain is likely, though some storms are also possible around the area, mainly towards western New Jersey and Orange County, NY. Eastern Long Island and eastern Connecticut are the most likely places to stay dry.

Friday - Sunday: Comfortable Temperatures Expected

Friday will continue with the isolated showers and thunderstorms, with the heaviest rain again to our south, with chilly temperatures again expected, similar to those of tomorrow, if not slightly cooler. By Saturday, more sunshine is expected, with temperatures likely to warm up into the lower to mid 80s across the area.

By Sunday, high temperatures will be slightly warmer, in the mid 80s for the immediate NYC area, but a cold front approaching will put an end to the dry conditions starting on Monday. An isolated shower or thunderstorm is possible for the western parts of the area.

Next Week: Stormy Pattern Develops

By Monday afternoon, a slow moving cold front should approach the area and may stall, with widespread showers and thunderstorms expected. Moisture from the remnants of Tropical Depression 5 will also be in place, combined with precipitable water values over 2 inches, will lead to a heavy rain threat for Monday through Tuesday night. The most extreme model runs were this morning's GFS runs, which showed a widespread area of 3-4 inches of rain. The GGEM is much drier, with the DGEX in between. At this time, a widespread 1/2 to 2 inches of rain are likely, with rainfall amounts locally as high as 3-4 inches. This is still in the longer range and can still change, and more details will come as the scenario for this time period becomes clearer.

Late next week, however, the GFS and DGEX models introduce an interesting possibility. They show a tropical system forming in the Gulf of Mexico, moving inland and bringing heavy rainfall for the East Coast, possibly including the NYC area. This is in the long range, and the models may not be as good in handling tropical cyclones in their longer range, but it is something to keep an eye on. Stay tuned for more details on this time period.

August 11 Tropics: TD 5 Dissipates

In this brief update, I will discuss the latest on the tropics, as well as Tropical Depression 5. A full update will be posted by 8 PM tonight.

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Tropical Depression 5: Last night, just as I was finishing my update, tropical depression 5 formed in the Gulf of Mexico, and I was not able to post much about it as new information was still coming in. Shortly after I posted my update last night, however, the convection quickly died down in the tropical depression, due to an unfavorable environment caused by a ULL, which is when it became apparent that TD5 may never get past tropical depression status. This ended up being the case, as Tropical Depression 5 dissipated just south of the Gulf coast, being the 2nd storm so far this season to dissipate in the Gulf of Mexico just before making landfall.

The remnants of TD5 are likely to bring heavy rainfall for the South, with its moisture combining with a cold front to produce a heavy rainfall event for the area. More details will be posted with the 8 PM update.

Invest 93: There is an invest in the middle of the Atlantic Ocean, which is currently weakening due to an unfavorable environment. I did not mention this invest in previous updates as it did not appear to have a high chance of developing into a tropical depression or storm, and now due to an increasingly unfavorable environment, this invest only has a low risk (less than 10%) of becoming a tropical depression or storm.

Leeward Islands: There is a weak tropical wave east of the Leeward Islands, moving westward. This tropical wave could develop in the longer range, however it is not a threat to develop into a tropical depression or storm in the short range.

Overall Summary: When I updated my hurricane season outlook a few days ago, I did expect more tropical waves to develop, however the question is how many of them manage to develop, being why I expected a range of 14-18 named storms. As we are now seeing, conditions are not very favorable for tropical development across the Atlantic, with a tropical depression having dissipated and two disturbances currently unable to develop into tropical cyclones. Later this season, the Atlantic Ocean is likely to become more favorable for more tropical cyclones to form, though I do not think at this time that there will be very high activity, keeping the total number of named storms below 18.

Tuesday, August 10, 2010

August 10: Heavy Rain Potential Next Week

Today ended up having more cloud cover than originally expected, with high temperatures lower than my forecast, in the upper 80s inland, and only peaking in the lower 90s for the immediate NYC area. Scattered showers were observed this morning across parts of the area, with most places seeing up to 0.1 inch of rain. While it will not be as hot for the next week, the cloud cover will generally be partly to mostly cloudy, with scattered showers and thunderstorms returning for late this week and the potential for heavy rain next week.

Tomorrow's Outlook:

Tomorrow will be partly cloudy for the area with a generally east to ENE wind expected. High temperatures will be in the upper 80s to lower 90s for most of the area except for Long Island and S CT, which will reach the lower to mid 80s, with a few upper 80s possible for western Long Island and SW CT.

Dry conditions are expected for most of the region, with heat expected again for Virginia with up to 100 degrees likely, with any chance of rain tomorrow likely to stay in Virginia and West Virginia.

Thursday - Saturday: Mainly Cloudy, Cooler And Some Storms Possible

Thursday and Friday are going to be mainly cloudy, with scattered showers and thunderstorms expected. Due to the cloud cover, cooler air mass, scattered showers and an onshore wind, high temperatures will be much cooler than the last few days, only peaking in the upper 70s to mid 80s across the area. These showers, however, should not be very widespread, with the best chance of rain to the south of the area, towards Virginia.

Saturday will be drier with some more sunshine, and despite an east wind persisting, high temperatures will warm up into the mid 80s for the immediate NYC area.

Sunday - Wednesday: Heavy Rain Potential

Sunday will warm up even more with high temperatures back into the mid to upper 80s for the immediate NYC area with increasing humidity, however the dry conditions will not last for long as a cold front is expected to affect the area. A cold front will enter the region on Sunday, and will move through very slowly, and could potentially stall in Pennsylvania. Some storms are possible for the western parts of the area on Sunday, with rain and storms starting for the rest of the area between Sunday night and Monday.

Precipitable water values during this time period will generally be over 2 inches, and with the set up shown, a heavy rain event is possible during this time period. The latest GFS run also shows this possibility, with as much as 3-4 inches of rain for the area between Sunday and Wednesday. There is still uncertainty as this is in the longer range, with models showing different timing and rainfall amounts, however rain is expected for this time period, with heavy rain also possible should the solution where the cold front stalls verifies. Stay tuned for more details on this time frame.

Tropics Update:

Tropical Depression 5 has just formed in the Gulf of Mexico, and is moving northwest. This tropical depression should intensify into a tropical storm and make landfall in Louisiana. I will post a full discussion on TD5 tomorrow, however it is likely that TD5 intensifies into at least a moderate tropical storm before landfall, potentially becoming a strong tropical storm if its environment is favorable enough.