Posts

Miguel Pierre

5/5 Late-AM Zones Update: Heavy Rain Today, Unsettled Weekend, More Blocking Next Week

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Happy Friday! A large, closed low to the southwest, will continue to impact the region today. Rain will continue to be heavy at times, early to mid-afternoon hours, as stronger southerly low-level jet moves across the region. Some embedded thunderstorms are also possible, with weak some instability this afternoon. Rainfall totals of at least 1” to 2” are expected for most areas. But some locally higher totals up 3”or 4” are possible. This could lead some flooding on area roadways and poor drainage areas.

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Miguel Pierre

5/4 Midday Zones Update: Heavy Rain Friday, Unsettled Pattern Going Forward

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Good afternoon! Today is the proverbial calm before the storm with plenty of sunshine so far today. Sunshine will begin filtering behind increasing high clouds later this afternoon, as high pressure also starts moving off the New England Coast. This will cause light winds to turn more southeasterly of the ocean and keep temperatures this afternoon,  in the mid-upper 50s closer the coast. While temperatures will still rise into the lower to middle 60s further inland, with less marine influence.

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Steven Copertino

Public Analysis: Warm End To the Week, Unusual Spring Pattern Setting Up

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Good afternoon!

After the dreary and cool weather we’ve been stuck in for the past few days due to the large and sluggish cut-off low pressure system earlier this week, conditions have finally improved rather markedly this afternoon. With clear skies, light westerly/southwesterly winds, and warm mid-level temperatures have allowed highs to reach into the upper 70’s and lower 80’s across the entire area. Some locations along the coast of Long Island and Connecticut have experienced a little more offshore flow this afternoon, therefor temperatures are stuck in the lower 70’s as of 2pm.

As we near the late afternoon hours and early evening, winds may turn more to the southeast ahead of a weak mid-level disturbance approaching our area. With winds out of the southeast, more moisture from off of the Atlantic may be able to work its way into the lower levels of the atmosphere and produce some overcast, especially for coastal sections of NJ and Long Island. After sunset, some locations closer to the coast may also have to deal with patchy fog as that moisture right off of the coast gets brought inland.

Later this evening and into very early tomorrow morning, we may have to watch out for the potential for some possible heavy rain as strong thunderstorms develop later this afternoon over portions of the Ohio Valley. These storms may wind up tracking through our area later on this evening and into tomorrow morning. These residual showers and possible thunderstorms would be fueled by the leftover instability provided by the southerly winds and approaching mid-level disturbance over Pennsylvania. The latest hi-resolution guidance has this activity reaching the area by 4-6 am, but if these storms do manage to maintain themselves, there could pose a threat for locally heavy downpours, gusty winds, and  some thunder. There are still uncertainties regarding these storms as they have not developed yet, but one concern is that they could slip to the south of the NYC area and cause little if any impact . Otherwise, tonight should be relatively warm as clouds work to trap the remaining heat in the low levels of the atmosphere, leading to lows in the upper 50’s and low 60’s.

Current conditions featuring the latest surface temperatures, visible satellite imagery, and regional radar mosaic, showing a very nice end to the work week.

Current conditions featuring the latest surface temperatures, visible satellite imagery, and regional radar mosaic, showing a very nice end to the work week.

Saturday and Sunday

As we move into tomorrow morning, some leftover showers and clouds may linger into the early afternoon hours, especially as a backdoor cold front works its way from north to south. While not as “intense” as the previous backdoor fronts that we have had over the past few weeks, this front will bring a mix of clouds and sun and gusty winds of around 25-35 mph during the afternoon hours. High temperatures tomorrow afternoon will be somewhat tricky to forecast depending on how far south the front can sag to the south, but highs should generally be in the upper 70’s and low 80’s across the entire area. It is worth mentioning that some locations in Southern New Jersey and portions of Southeast Pennsylvania could possibly see highs in the mid-upper 80’s with enough sun.

It is worth mentioning that there is some potential for some isolated showers and thunderstorms late tomorrow afternoon and evening as the backdoor front sags south through Pennsylvania and New Jersey. Instability will be quite high to the south of this front, and wind shear will also be quite supportive of some strong or possibly very isolated severe thunderstorms which may produce some isolated large hail, locally heavy rainfall, and damaging winds. However, due to the lack of a “trigger” to set these storms off, and the fact that the cold front could be well south of the immediate NYC metro area by the time the other ingredients are in place, we do not anticipate widespread significant severe weather tomorrow afternoon. Otherwise, Tomorrow evening will definitely be much cooler than Friday, as the cold front leaves behind cooler winds from the north west, with lows in the lower 50’s to upper 40’s further inland.

On Sunday a much cooler airmass will be over the region as maritime floods the entire area due to winds coming in from the Atlantic ocean. While starting off relatively cool in the morning, a mix of sun and clouds and calmer winds from a high pressure system to the north east will allow temperatures to get into the low to middle 60’s across the area, which is around 8-10 degrees below normal for this time of year!

Later in the evening, we may see the stalled out front over portions of the Mid-Atlantic begin to return northwards with some warmer air and clouds, but at this time the timing and placement of this feature is somewhat uncertain. Overall, we expect cloudiness and possibly some showers to take over during the evening on Sunday.

This afternoons 12km North American model showing a rather significant amount of instability to the south of the NYC metro on Saturday afternoon (Valid 4pm Saturday)

This afternoons 12km North American model showing a rather significant amount of instability to the south of the NYC metro on Saturday afternoon (Valid 4pm Saturday)

Monday and Early Tuesday 

As mentioned, there are some very significant uncertainties as to how far north the front will advance once again on Monday, as this will be crucial in determining how the day plays out. If the front happens to reach far enough north of our region by the afternoon hours, we could see a very warm and pleasant day on Monday with highs in the upper 70’s and low 80’s once again. However, even if this warmer solution is realized on Monday, a very large system is expected to be gathering in the Great Lakes region Monday evening.

As this system continue to move north and east through the Great Lakes region very late Monday and into Tuesday, it should drag a rather strong cold front through our area. This cold front will have access to deep tropical moisture, extending all the way from the Gulf of Mexico, so there is a real threat for heavy rain and potential thunderstorms associated with this cold front as it progresses through our area.  At this time, it appears that the showers and thunderstorms will be passing through during the evening hours, so the overall severity of the associated thunderstorms should be quite limited.

Extended Range

A cooler airmass is expected to trail the front later in the day on Tuesday and into Wednesday, but the main story will be the ensuing pattern that will be taking shape. We have talked about the North Atlantic Oscillation many times in the past, and especially during the winter months since it is such a large factor in helping to get large coastal storms to drop copious amounts of precipitation over our area when it heads towards its negative phase. In an interesting series of events, it now seems that a very large and powerful ridge will be setting up over Greenland during the middle of next week. If this actually does materialize, and most of the computer model guidance does support it, then we could be entering a rather cool and stormy pattern for at least the next 7-10 days across the Northeast.

Interestingly enough, the models have even been beginning to show a series of potential coastal storms in the long range taking tracks quite similar to storm tracks that we would see during the Winter months! We will continue to monitor this very interesting pattern over the next few days and provide updates and more details become available!

GFS and ECMWF ensembles both agreeing on an extended period of a negative NAO, which could promote cool and stormy weather in the east

GFS and ECMWF ensembles both agreeing on an extended period of a negative NAO, which could promote cool and stormy weather in the east

For more information and posts like this one, make sure you sign up for Zone Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

Have a great weekend!

Steve Copertino

Steven Copertino

Public Analysis: Warm End To the Week, Turning Unsettled Once Again

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Good Afternoon!

Things are finally clearing up after the cut-off low pressure system that we talked about on Monday came through the region most of the day yesterday. As stated in the earlier outlook, the precipitation was more on the scattered, but heavier side, so some locations did indeed see higher rainfall totals than other locations. For example, portion of Northwestern New Jersey saw around around a quarter of an inch of rain, while areas just south of the city saw close to 2 inches of rain due to training of showers.

As the area of low pressure continues to decay, it has pretty much rained itself out for the most part, although there is some residual low level moisture hanging around. This residual moisture has brought some light drizzle and even isolated showers to parts of the metro area, but any threat for significant precipitation is pretty much over as dry air works in from the north and west. As the precipitation dies off this afternoon, relatively thick cloud cover associated with the decaying low pressure system will moderate temperatures and keep them limited to the upper 50’s to lower 60’s across the entire area this afternoon.

As we progress into the evening hours, expect the cloudy conditions to continue on through this evening as one last band of moisture trapped in the lower levels of the atmosphere swings through. This last little band of moisture should work to keep skies mostly cloudy and could even produce some areas of fog due to the winds being relatively low this evening. With the cloudiness limiting how much temperatures will be able to fall, lows are expected to remain rather steadfast in the 50’s overnight, which is slightly above normal for this time of year.

Latest visible satellite imagery, regional radar mosaic, surface temperatures, and surface winds for the Northeast this afternoon (Courtesy of GREarth)

Latest visible satellite imagery, regional radar mosaic, surface temperatures, and surface winds for the Northeast this afternoon (Courtesy of GREarth)

Thursday and Friday 

As we head into tomorrow, the cut-off low pressure system should still be located to our east while continuing to dissipate and slowly limp away from the coast. As it does so, the low will still have lingering effects on our area by continuing to bring winds from the southeast off of the Atlantic, which may keep overcast and some broken clouds over the area to start off the first half of the day. Though, as we continue on through the day, more sun should begin to mix in with the clouds and allow things to warm up when compared to today. Highs should reach into the upper 60’s and lower 70’s for most of the area-with the chance at some higher temperatures if the cloud cover is able to erode quicker.

Tomorrow evening should be give way to partly cloudy conditions, especially towards midnight and into very early Friday morning. A weak cold front will be working towards the area from west to east and bring a small chance at some showers and possibly even a weak thunderstorm during the evening hours. Right now it appears that the greatest chance for showers and a weak thunderstorm will be over central and eastern portions of Pennsylvania, but this activity may continue east with time during the early morning hours towards New Jersey and southern New York. However, the rain potential with this front will be severely limited as dry air from Canada works its way into this weak front as it continues east towards the coast by daybreak Friday.

During the late morning on Friday, the remnants of the cold front should be over eastern Long Island and steadily heading out to sea, leaving behind dry and clear conditions. With relatively clear skies and winds from the south/southwest behind the front during Friday afternoon, temperatures should have no problem reaching well into the 70’s and possibly low 80s across portions of southeast Pennsylvania as well as southern New Jersey.

The entire area should see a very nice end to the work week as the warm temperatures and warm skies continue through sunset. Due to a building ridge of high pressure to the south, lows will remain relatively warm, in the 60’s Friday night with light southerly winds.

12z 3km North American Model showing a very pleasant and warm Spring day on Friday with highs in the 70's and 80's across the Northeast (Valid 4pm Friday)

12z 3km North American Model showing a very pleasant and warm Spring day on Friday with highs in the 70’s and 80’s across the Northeast (Valid 4pm Friday)

Saturday and Sunday

With an area of ridging and high pressure building in from the east to west on Saturday morning from off the Mid-Atlantic coast, conditions during the morning hours should be quite warm. Temperatures during the mid morning hours should be in the mid to upper 70’s across the entire area and continuing to climb into the mid 80’s by the afternoon. Due to some winds out of the south, south-facing shores of Long Island and Connecticut may experience somewhat lower temperatures, but overall the majority of Saturday looks to be on track for a very warm Spring day.

As we progress into the mid to late afternoon hours on Saturday, the latest computer model guidance has been showing the possibility of a backdoor cold front moving through the region later in the day. As the cold front begins to push south during the day, there may be enough instability and moisture around for showers and thunderstorms to develop ahead of this frontal system. The exact details of any showers and thunderstorms will have to be worked out over the next few days, but if conditions do come together in the right manner, some strong to possibly severe thunderstorms may exist over portions of the area, with hail and gusty winds.

Otherwise, once the backdoor cold front pushes through the area late Saturday and into Sunday, conditions should once again become much cooler and clear during the day Sunday with high pressure located just to our east. Temperatures will be highly dependant on just how far south the front can get, but right now it seems likely that temperatures across the area should remain in the mid to upper 60’s with isolated areas of 70’s, due to winds coming in from the cooler Atlantic Ocean.

The potential for onshore winds will also bring the chance for some cloudier weather during the day, however if the cold front pushes far enough south then the aforementioned high pressure will be able to position itself over our area, which would allow more sun than clouds. These backdoor fronts are extremely hard to predict, even in the short range, so we will be updating you on the latest over the next few days.

Once we head into Sunday evening a very large and vigorous system will be taking shape over the central part of the country, which is part of this active weather regime we warned of over a week ago now!

12z GFS model showing a very large and impressive system over the central portion of the country poised to impact the Northeast early next week (Valid 8pm Sunday)

12z GFS model showing a very large and impressive system over the central portion of the country poised to impact the Northeast early next week (Valid 8pm Sunday)

Extended Range

The large and potent storm system located over the North Central portion of the country will have the potential to impact our region well before the low pressure nears the area. As the stalled backdoor cold front from Sunday begins to lift north over our area on Monday, warmer temperatures and some clearing may be possible, however if this front is slower or does not progress as far north as currently progged, then conditions may remain cooler with the threat of some showers with increased cloudiness. At this time, we remain skeptical on the northward progress of the warm front, due to departing high pressure, off the New England coast, supporting more onshore winds and cooler temperatures.

As the system in the Plains begins to move east late Monday and Tuesday, a stronger cold front should be approaching the area. This front will have the potential to produce a myriad of impacts such as heavy rains, thunderstorms, and gusty winds. All of this is highly dependant on the timing of the system once it is located in the Plains this weekend, so make sure to check back on Friday and Monday for future updates on this potential system!

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For more information and posts like this one, make sure you sign up for Zone Forecasts — where multiple detailed articles, videos, and interactives are posted each day. Also, come interact with our staff and many other weather enthusiasts at 33andrain.com!

Have a great evening!

Steve Copertino