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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Have a great evening!

Steve Copertino

Steven Copertino

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

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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!

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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

Steven Copertino

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

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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!

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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 weekend!

Steve Copertino

Steven Copertino

Public Analysis: Much Cooler Today, Multiple Rain Threats Ahead

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Good Afternoon!

High pressure off of the Canadian maritimes has set up in the perfect position today to usher in cool winds from the Atlantic, keeping temperatures a good 10-12 degrees below what they were just 24 hours ago. In addition to the cooler winds from the southeast, clouds and even some light showers have been noted across the western portions of the area this afternoon. Back to the east, there have been some breaks in the clouds noted on visible satellite imagery over parts of New Jersey and New York. Even with these breaks in the cloud deck temperatures have not been able to get much higher than the low to mid 50’s, with temperatures in the 40’s being reported over portions of Long Island and Connecticut.

Cloudy skies and cooler temperatures should continue to be the theme for the rest of today as a mid-level warm front begins to approach from the west later this afternoon and into the evening hours. This front will bring increasingly cloudy skies and even the threat of some showers later this evening as available moisture begins to increase in conjunction with the passing of this front.

As the evening progresses onwards, a very weak cold front associated with a disturbance in Canada will pass through the region and bring yet another chance at some more showers as lift with this system is only slightly stronger than the warm front that preceded it. Overall, it should be a rather raw and dreary afternoon and evening as temperatures remain pretty much capped off in the 40’s to low 50’s across the entire area.

Latest visible satellite imagery, surface temperatures, and regional radar mosaic showing a relatively cool Spring day (Courtesy of GREarth)

Latest visible satellite imagery, surface temperatures, and regional radar mosaic showing a relatively cool Spring day (Courtesy of GREarth)

Thursday into Friday Afternoon 

Tomorrow morning should start off with some broken clouds across the metro area as weak upper level energy riding up and over an area of high pressure. At this time it seems that any shower  activity  should remain quite limited, though some areas of drizzle may be possible along the coast early on in the morning. As tomorrow continues on, a surface warm front looks to move north through the region and provide a renewed chance at some more low to mid-level cloudiness as more warm/moist air begins to work its way in.

There are still some questions as to how much warming occurs tomorrow with the combination of some leftover southeasterly winds off of the Atlantic, as well as increasing cloudiness, but it does look like tomorrow will at least be a warmer day than today. Temperature should be able to rise into the mid to upper 60’s for locations away from the coast, but highs may struggle to get out of the 50’s for coastal sections of New Jersey, Long Island, and Connecticut. Some inland locations of New Jersey and Pennsylvania may have a chance at reaching the low 70’s, but this will be highly dependant on the aforementioned variables.

The area of low pressure that we mentioned back in Friday’s discussion will begin to track through the upper Great Lakes region late Thursday afternoon and evening, and this will bring yet another warm front for our area later in the evening. However, confidence decreases significantly as a high pressure system coming down from central Canada and stalling over portions of southeast Canada may work to stall this warm fronts progress. Where this warm front stalls will dictate where cooler temperatures setup Thursday night. Areas north of the front will see lows back into the 40’s and low 50’s. Areas to the south will see temperatures remain in the 50’s to possibly even low 60’s overnight as southerly flow increases.

Unlike the warm front passing through this evening, the front tomorrow night and into Friday morning should have enough moisture and dynamics associated with the area of low pressure passing to our north to provide a decent chance at some showers and even thunderstorms. With limited instability, a strong low level flow, and deep moisture transport, it appears that there will be a chance at some convection possibly developing during the evening hours. The main threat with these storms appears to be locally heavy rainfall and possibly some flooding for areas with poor drainage, so make sure to stay up to date on these possible storms over the next 24 hours.

15z Rapid Precesion Model showing some heavy showers and thunderstorms developing from west to east on Thursday evening and into Friday (Courtesy of WSI)

15z Rapid Precession Model showing some heavy showers and thunderstorms developing from west to east on Thursday evening and into Friday (Courtesy of WSI)

Friday Evening and Beyond

Finally, a cold front, will come through later Friday afternoon and evening. But any more showers will be more widely scattered with less lift and instability along and ahead of this front. Skies will finally clear later Friday night and Saturday, as weak high pressure build into the Northeast, behind this storm system. Sunshine with northwest downslope winds on will help temperatures rise into back into the lower to middle 60s on Saturday afternoon.

As we continue onwards, the active pattern looks to continue as the computer models are keying in on the potential for a storm system to approach from the southwest on Saturday evening, however they diverge significantly on the strength and timing of this system. As of this afternoon it appears that at least moderate rain appears likely as this system tracks to our south, and then stalls off the Mid Atlantic coast on Sunday.

It is worth noting that this system will be moving across the southern Plains and will have time to take in a considerable amount of water vapor before it reaches our area and it is also important to mention that with a considerable amount of time left in this forecast, there is the potential that this system could trend stronger when it passes to our south as well as potentially stall closer to the coast than what some of the models currently have. This would possibly bring a more significant system for our area on Sunday and possibly into Monday, with heavy rain and even some strong winds possible for the coast.

12z European model showing an area of low pressure over the Southeast US states potentially bringing the threat of moderate rains later this weekend (Courtesy of Accuweather Pro)

12z European model showing an area of low pressure over the Southeast US states potentially bringing the threat of moderate rains later this weekend (Courtesy of Accuweather Pro)

Make sure to stay tuned over the next few days for updates on the potential storms tomorrow evening, and our next storm chance this weekend!

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