ScreenHunter_311 Apr. 28 14.43

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

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

ScreenHunter_311 Apr. 26 16.38

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

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!

————————————-

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

ScreenHunter_310 Apr. 24 15.19

Public Analysis: Cut-off Low Woes, Possible Clearing Late Week?

Good afternoon!

The cutoff low that we talked about late last week has indeed trended a bit closer to the coast, which means more significant/prolonged impacts than previously thought, as model guidance has trended towards a weaker and more progressive area of high pressure during the past few days. Overall, this means that the threat for locally heavy rain, some gusty winds, and possible minor coastal flooding has increased.

With much more cloud cover and and cooler temperatures ushered in from winds coming in off of the Atlantic this afternoon, today has been yet another glum and dreary day across the entire NYC metro area. Underneath this thick later of cloud cover, temperatures have struggled to get out of the 50’s this afternoon, with only a few stations in Northern New Jersey, Southern New York, and portions of Connecticut reporting highs in the low 60’s.

As we continue through the day, not much change is expected at all with regards to cloudiness as we near sunset. Some areas of light showers may be possible, but with a wedge of drier air in the low levels of the atmosphere, no significant rains are expected through the rest of today. With heavy cloud cover and the prolonged easterly winds from the Atlantic, lows should remain in the 40’s to low 50’s across the entire area this evening, with far northern sections having a shot a seeing some slightly warmer temperatures.

Latest regional radar mosaic, visible satellite imagery, surface winds, and surface temperatures showing the beginnings of the coastal lows influence on our area's weather (Courtesy of GREarth)

Latest regional radar mosaic, visible satellite imagery, surface winds, and surface temperatures showing the beginnings of the coastal lows influence on our area’s weather (Courtesy of GREarth)

Tuesday Into Tuesday Night

As the coastal low begins to strengthen late this evening and into very early Tuesday morning, the easterly winds from the Atlantic should begin to strengthen quite a bit.  These easterly winds will bring in moisture from the Atlantic, and also the risk of some heavier showers during the early morning hours. With the increased moisture and the strengthening low levels winds, some of these heavier showers could produce brief heavy downpours and some brief gusty winds. As the morning continues on, areas of continued showers and some areas of fog along the coast are possible with abundant low level moisture.

Once we progress into the early afternoon hours, things should begin to go downhill with much more steady rain likely across the entire metro area. With the core of the low level jet starting to work its way up the coast by around 11 am, heavy downpours and windier conditions will increase from south to north. Conditions will likely remain steady or slightly worse as the afternoon progresses and the low pressure area continues to creep northward. Latest high resolution model guidance indicates that the precipitation with this system may be more convective (or spread out) in nature, instead of a uniform “shield” of moderate rain, so rainfall amounts may vary quite a bit during the afternoon and early evening hours.

As the storm continues into tomorrow evening, the low level jet should be directly overhead and this should bring the heaviest impact for our area. Heavy rains should be streaming in from the south/southeast during the evening hours, with locally heavy downpours possible. Some gusty winds of around 35-45 mph will be possible in some of the heaviest downpours, as stronger winds just above the surface are able to mix down.

Overall, we will have to monitor conditions closely tomorrow afternoon and evening as there is a small chance at some localized flooding in poor drainage areas and in locations that are caught underneath any possible training of heavier showers. When all is said and done, rain totals should be around 1-2″ across the region, with some locations possibly seeing amounts near 3″. Please listen to your local National Weather Service tomorrow afternoon for any possible Flash Flood Warnings that may be issued.

12z 3km North American Model showing heavy rain funneling in over the area tomorrow evening with the low level jet (wind barbs) directly over the NYC area (Courtesy of GREarth)

12z 3km North American Model showing heavy rain funneling in over the area tomorrow evening with the low level jet (wind barbs) directly over the NYC area (Courtesy of GREarth)

Wednesday and Thursday 

Early Wednesday morning the cut-off low pressure system should be just to the east of the area and weakening at a steady pace as it begins to fill in with dry air. This should work to dissipate the remaining precipitation on Wednesday morning from west to east, but some remaining clouds and light showers will be possible during the afternoon. Temperatures on Wednesday will be highly dependant on whether or not the low pressure system can weaken enough to allow the remaining cloud cover to burn off and let the sun break through. Current indications are that the cloud cover may stick around longer towards the eastern half of the area, thus limiting temperatures to the mid to upper 50’s, where locations to the north and west of the NYC area may see highs in the low 60’s.

Compared to tomorrow, Thursday should be a much improved day as ridging in the mid levels of the atmosphere begins to build in over the area. This should allow winds to shift to the south/southwest during the day on Thursday and allow temperatures to reach much more seasonable levels for this time of year, with highs possibly reaching the low to mid 70’s across interior sections. Coastal locations in NJ, CT, and Long Island may have to deal with a cooler offshore flow, but since that is a ways out right now, it remains uncertain.

12z GFS showing a much more seasonable and pleasant day across the entire area with highs in the 70's and light winds from the south

12z GFS showing a much more seasonable and pleasant day across the entire area with highs in the 70’s and light winds from the south

Extended Range

The brief lull in activity should be short-lived later this week as multiple systems out to our west begin to head east underneath high pressure in Canada. These systems have the potential to bring wet and potentially stormy weather once again in the long range, with even the chance at some thunderstorms once the pattern becomes more conducive. In addition to the more active weather, we could also see the return of backdoor cold fronts which could make an appearance late next weekend or into early next week, but model guidance has been inconsistent over the past few cycles, so we will have to monitor this over the coming days.

With the potential for more heavy rain and some possible flash flooding tomorrow, make sure to check back for future updates!

——————

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

img

Public Analysis: Cool and Damp Friday, Coastal Cut-Off Next Week?

Good afternoon and Happy Friday!

Today has been another unsettled and damp day as rather thick cloud cover and some associated showers have worked their way through the region late last night and into the morning. This was due largely in part from a retreating back door cold front, or a cold front that sinks from northeast to southeast due to more dense air being able to overcome the more shallow and weak warm layer to the south. Offshore winds and thick cloud cover should remain over the remainder of the afternoon, and there does exist the potential for some patchy areas of drizzle or even a shower or two. Any steadier showers will likely be limited to areas along the coasts of New Jersey and Long Island, as the marine influence will be greatest along those areas.

With this aforementioned cloud cover and the back door cold front established well to our south and west, temperatures in North and Central New Jersey, as well as points to the north will struggle to reach out of the mid 50’s this afternoon. Further south into southern portions of New Jersey as well as southeast Pennsylvania, we may see temperatures reach into the low to middle 60’s, but this is highly dependent on whether or not if the warm sector in central Pennsylvania is able to advance during the late afternoon hours.

Some more steady showers and possibly even a thunderstorm or two may be possible for portions of southeast Pennsylvania as well as southern New Jersey later into this evening, but as of right now, it is looking like any shower /thunderstorm development will be isolated in nature. Weak instability, moderate wind shear, and some clearing skies over central Pennsylvania has lead to an area where we may see these potential showers and storms develop and potentially progress east during the afternoon hours. This area will be monitored for any potential development, so make sure to check in here for the latest and on our twitter page @nymetrowx for up to the minute updates! Due to the risk of some weak/isolated severe thunderstorms, the Storm Prediction Center in Norman Oklahoma has place portions of our area in a Marginal Risk for large hail and potentially damaging wind gusts. Heavy rain and cloud to ground lightning will also be possible with any stronger storms, so make sure to be aware of any approaching storms later on.

Latest surface temperatures, regional radar mosaic, and visible satellite imagery across the Northeast showing the very stark temperature gradient in place this afternoon (Courtesy of GREarth)

Latest surface temperatures, regional radar mosaic, and visible satellite imagery across the Northeast showing the very stark temperature gradient in place this afternoon (Courtesy of GREarth)

As we move on through the day and into the evening, a cold front will begin to push through the region later this evening. However, there is a chance that some moisture will be trapped in the lower levels of the atmosphere later on tonight, which could cause some low clouds and areas of patchy fog to remain late tonight and early tomorrow morning, especially closer to coast. Cloud cover will significantly dampen any chance of radiational cooling tonight, which should  keep temperatures from dropping out of upper 40s to lower 50s overnight over much of the region. Some interior valleys could be a little cooler in the lower to middle 40s, which is a good 8-14 degrees below normal for this time of year.

Saturday Into Sunday 

As the cold front continues to push through the southern Mid Atlantic region tomorrow morning, broken clouds and even some overcast will be possible as some residual moisture continues to stick around in the lowest levels of the atmosphere. The short-term models disagree on whether or not the cloudiness will burn off or not through the afternoon hours, but we do expect some peeks of sunshine tomorrow with a relatively cool air mass settling in tomorrow. With some limited cloud cover, light winds, and cooler mid level temperatures expected tomorrow, temperatures should be able to only rise into the low to middle 50’s across most of the New York metro area, with the possibility of interior locations possible seeing highs limited to the upper 50’s due to cool northwesterly winds from Canada. These winds will also usher in some more dry air into the mix, so expect any residual clouds to gradually fade iater into the day.

Sunday will be the beginning of another unstable period as a low pressure system in the mid levels of the atmosphere “cuts off” from the main flow and begins to meander towards the southeast coast of the United States. This low pressure will have a very nice feed of moisture from the Gulf of Mexico, so it’s overall precipitation field should be quite large in nature, as well as have the potential to drop a moderate to heavy amount of rain wherever it does track. This afternoons guidance really has not converged on any particular solutions, with some models bringing the low from the Outer Banks of North Carolina, to just offshore of the southern coast of Long Island, while other models have the system meandering off the Mid Atlantic coast with little, if any direct impacts through Sunday and Monday.

As of right now, we expect that this system will not be able to gain enough latitude once it reaches the southeast coast to impact our area with any significant rains or winds at this time. High pressure centered in Canada will likely keep this system offshore throughout this period, but this system will need to be monitored, as a small deviation in overall setup could chance the forecast quite a bit.

12z GFS model showing the large cutoff low pressure system stalling out and remaining off of the Mid-Atlantic coast throughout the weekend and into early next week.

Extended Range  

Stronger ridging should begin to develop over our area on Monday and into Tuesday, and this will begin to force the remnants of the cutoff low to the south and east early next week. This should allow any significant impacts like heavy rain and winds to remain well-offshore before the system gradually weakens and heads out to sea. More unsettled weather will likely take shape once again as a very active Pacific jet stream begins to set up off of the west coast of the United States.

This very active jet stream will have the potential to place a deep trough in the central portions of the country, which would in turn bring a large ridge of high pressure into the southeastern region of the country. This combination would be capable of bringing temperatures well-above normal next week for the Northeast, along with the risk for multiple rounds of severe storms in the Plains states and on east, possibly beginning on Wednesday. Regardless of the exact details, it does look like we are possibly heading into a very active and warm pattern once again, so make sure to stay tuned over the next few days for more updates!

——————

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