Posts

Steven Copertino

Public Analysis: Another Week of Extremes on Tap

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If you enjoyed the record warm temperatures, severe weather, and sudden return to more winter-like conditions that we experienced over the past week, then you’re in luck! This week is shaping up to be very similar to last, with record or near-record temperatures possible in the middle of the week, followed by a strong cold front passage that will leave the entire area right around seasonable or just slightly below average for this time of year with a possible clipper system passing near the area by the end of the work week.

This afternoon was rather pleasant with some mid to high level clouds noted on visible satellite imagery as a high pressure system located off of the mid-Atlantic coast remains in control of our weather for the rest of the day and into tomorrow. As we progress into late afternoon hours and evening, cloud cover will begin to increase over the entire area as southerly winds usher in a moist airmass in the low levels of the atmosphere. Since the cloud cover will be relatively heavy, temperatures will have a hard time dropping much this evening, so expect temperatures to only be in the mid to high 30’s inland and in the lower 40’s for the coastal regions as well as southern locations. Some patchy drizzle may be possible as the low level moisture mentioned earlier begins to increase as we head into the evening hours.

Current visible satellite and surface observations showing a rather thick cloud deck overspreading the Northeast (Simuawips.com)

Current visible satellite and surface observations showing a rather thick cloud deck overspreading the Northeast (Simuawips.com)

As we move into Tuesday, a warm front should gradually begin to overspread the region in the morning and bring a cloudy start to the day. As we progress into the afternoon hours, temperatures should rise into the upper 50’s to mid 60’s areawide, with cooler temperatures around the mid 50’s likely along coastal locations. High level clouds may allow some sunshine to break through tomorrow afternoon, but as another warm front moves through in conjunction with some upper level energy from a disturbance passing near our area, low clouds and even some rain are quite possible by the afternoon. Low level clouds should continue to increase into the evening hours, with some steadier rain showers possible by late evening. Though winds look to be a little too strong for fog in the evening, warm winds coming off of the ocean and low level moisture in place may allow for at least the coastal communities to see some periods of fog, though this will have to be looked at in greater detail as we get closer to tomorrow evening.

NAM model showing winds coming off of the Atlantic on Tuesday afternoon, providing cloudy conditions as well as a threat for showers later in the day

NAM model showing winds coming off of the Atlantic on Tuesday afternoon, providing cloudy conditions as well as a threat for showers later in the day into the evening hours

Wednesday should be the most eventful day of the week in terms of sensible weather as the warm front that initially approaches the region tomorrow begins to advance north. The initial fog and rain showers should diminish by late morning, giving way to at least some sun breaking through the clouds. Temperatures should quickly rise deep into the 60’s and even low to mid 70’s by the afternoon hours, which could break numerous records once again across our area. Since we still do hold on to southerly winds, coastal sections as well as Long Isalnd may be limited as to just how warm they get.

As a strong cold front associated with a low pressure system moves through the Great Lakes Wednesday afternoon, winds from the south will usher in a very moist airmass for this time of year which will allow the atmosphere to become quite unstable. Even before the cold front and its associated “lift” which helps to build thunderstorms arrives, some showers and thunderstorms will be possible by the early afternoon hours. These shower and possible thunderstorms will mainly be limited to heavy rain and perhaps some gusty winds, but after these initial storms pass through is when the main event of the day looks to unfold. As we begin to destabilize the atmosphere again later in the afternoon, very strong upper level wind shear as well as significant lift will be present over the metro area, which will be quite favorable for organized severe thunderstorm development capable of potentially damaging winds. Though model guidance is beginning to key in on the potential for severe thunderstorms to pass near or over the area later in the day and into the evening, there are still some very important details that will have to be worked out during the day on Wednesday. One of the key factors to this potential severe weather threat will be just how widespread the initial showers and thunderstorm development is Wednesday morning, which will ultimately determine where the best instability is located, as well as where the leftover low level boundaries are located (which could locally enhance storm development). As of this morning, the Storm Prediction Center in Norman Oklahoma has placed our area in a Slight Risk for severe thunderstorms on Wednesday with damaging wind gusts being the most likely risk at this time. Make sure to stay tuned as we will have continuing coverage of this potential severe threat over the next 48 hours.

Afternoon NAM model showing strong thunderstorms approaching the tr-state area by late afternoon

Afternoon NAM model showing strong thunderstorms approaching the tr-state area by late afternoon

Behind the front will come a dramatically changed weather pattern. Thousands of miles to our north, a blocking ridge near Greenland will begin to have its effects on the weather throughout the hemisphere. Northern jet stream disturbances will slide southward through the Great Lakes and into New England, with colder air lingering across the Northeast parts of the United States. The first of these disturbances comes late this week in the form of a transient clipper system. Forecast models have wavered with the storms exact track, but a weak low pressure area tracking quickly through the Northeast US on Friday holds the potential to deliver some light snow — especially in New England. The exact track of the low pressure area will determine where the swath of light wintry precipitation falls. Make sure to stay updated with the active weather week ahead! 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.

 

Have a great evening!

Steven Copertino

Public Analysis: Record-breaking Warmth Gives Way To Seasonable Weather

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Today has been yet another absolutely beautiful day with scattered clouds and light winds making for an excellent and unusual end to another February workweek. After a cold front and possible associated line of showers and thunderstorms move through tomorrow, a return to more seasonable temperatures is likely.

Temperatures this afternoon have soared into the low to mid 70’s across much of the area. with coastal locations along Long Island and Connecticut seeing temperatures a bit lower in the mid 60’s. As was mentioned as early as Monday, these temperatures are 25-35 degrees above normal for this time of year, and as a result, numerous monthly high temperature records are falling across the entire Northeast. All of this warmth has been caused by a high pressure system over the western Atlantic that continues to provide winds out of the southwest that will continue through this afternoon. As we progress through the afternoon and into the evening, the persistent ridging and attendant high pressure system will begin to give way to a stronger mid-level disturbance currently located over the central Plains this afternoon. (This system is also responsible for the marginal severe threat in the Ohio Valley this afternoon and evening-see our Severe Analysis for more on this event)

A look at the record-breaking temperatures across the metro area this afternoon

A look at the record-breaking temperatures across the metro area this afternoon

As the influence from this system increases later this evening, the amount of moisture available in the atmosphere will also increase. This low level moisture will become trapped underneath a temperature inversion, which will act as a “lid”, and enhance the possibility for some dense fog for coastal regions this evening and lasting into early tomorrow. This moisture should linger into the morning hours, with low level clouds and even some patchy drizzle taking place in the areas that have more available moisture to work with. As we move into Saturday afternoon, temperatures should not be as warm as today as winds from the southeast start to work into the metro and limit highs to the upper 60’s for inland locations and 50’s for the coast. Some locations that are stuck underneath prolonged low level clouds tomorrow afternoon will also struggle to really warm up too much tomorrow afternoon.

HRRR model showing limited surface visibility tomorrow morning (Valid 7am)

HRRR model showing limited surface visibility tomorrow morning due to low clouds and fog (Valid 7am)

The main story tomorrow will be a cold front advancing eastward from the Ohio Valley and into Pennsylvania by tomorrow afternoon. Due to some limited instability as well as some lift provided by the upper level jet overspreading the area, a line of showers and thunderstorms will likely develop over Pennsylvania early tomorrow afternoon and quickly race eastward. As this line of thunderstorms reaches eastern Pennsylvania, southern New York, and New Jersey, what limited instability and dynamics that this line had to begin with will gradually fade. As a result, by the time the line of showers and thunderstorms reaches our area they should begin to weaken quite a bit. Heavy downpours, some brief gusty winds, and even some thunder are all possible, especially across inland zones.

3km NAM showing line of thunderstorms and associated showers along the cold front (Valid 3pm Saturday)

3km NAM showing line of thunderstorms and associated showers along the cold front (Valid 3pm Saturday)

After the front moves through late tomorrow afternoon/evening, some lingering showers will be possible as temperatures begin to return to seasonable levels, and then even back down to below-normal temperatures by early Sunday morning. Although this below-normal period of temperatures appears to be short-lived, it should be quite the contrast from what we have seen over the past week or so. Once we get into the upcoming work week, temperatures should hover around normal to slightly above-normal with the chance for a few weak disturbances passing near our area to provide some precipitation for the area starting on Monday. This unsettled weather will continue for the rest of the week, but as we move on in time, long range guidance is beginning to indicate that the very fast flow that has prevented a few significant winter storms this season will begin to relax. This could possibly lead to at least some cooler weather and possibly a full return to winter by March. Make sure to stay tuned for updates on tomorrow’s possible heavy rain threat as well as the evolving long range pattern! 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.

Have a great weekend!

Steven Copertino

Public Analysis: Unusual Febuary Warmth, Unsettled Saturday

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Another very warm end to the work week is on tap with temperatures leveling off on Saturday as a cold front moves through the region and provides a chance for some much needed precipitation for the area.

After some overcast and lingering sprinkles this morning that moved over the Lower Hudson Valley and Long Island, the associated  overcast and showers have eased up enough to allow for temperatures to reach into the 50’s across much of the area this afternoon. With just middle to high level cloud cover persisting the rest of the afternoon, the Metro area should continue to see temperatures rise into the 50’s, with even some 60 degree readings possible in the southern half of New Jersey. As a very weak mid level disturbance dissipates while it quickly moves off to the east this evening, high pressure centered over the Atlantic will remain in control of our weather as we head into the evening and will help to provide a very light southerly flow. This southerly flow may introduce some moisture at the lower levels of the atmosphere very close to the surface that could produce areas of fog. The fog may reduce visibilities quite a bit in some locations, so use caution if driving. Otherwise, temperatures this evening will drop down into the 30’s for inland sections, and into the low to mid 40’s for the coastal areas which is just about average for this time of year.

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Steven Copertino

Public Analysis: Beautiful Presidents Day Weekend, Unsettled Next Week

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After very blustery conditions with harsh windchills the past few days, we’re on tap for a beautiful Presidents Day weekend with clear and dry conditions expected over the entire region

Despite temperatures in the upper 30’s to low 40’s across most of the area this afternoon, the winds that have been present over the past two days due to the large area of low pressure was located to our east has finally moved on. This has allowed the winds to calm significantly and eliminated any real windchills from the area, making for seasonable conditions. This afternoons visible satellite imagery shows very little in the way of any cloud cover as a weak area of high pressure centered near Buffalo, New York remains in control throughout the rest of the day. This  should provide a very nice close to the work week with only high clouds possible towards sunset. Later this afternoon and this evening, a warm front located to our south will begin to move to the north and overspread the area by tomorrow morning. This front should initially usher in some mid-level clouds tomorrow morning, but these should be short-lived as tomorrow afternoon should be an excellent day for outdoor activities as the clouds burn off and the entire area sees temperatures climb well into the 50’s for the NYC metro and NE NJ, while locations closer to the coast remain limited to the upper 40’s and low 50’s. It is also quite likely that given the amount of warm air advecting into the region on Saturday, that portions of Central and Southern New Jersey reach temperatures at or above 60 degrees! This airmass is quite unseasonable for this time of year and most of the area will be running 10-18 degrees above normal on Saturday.

Visible satellite imagery of the Northeast showing relatively calm conditions and little in the way of cloud cover (Courtesy of Simuawips.com)

Visible satellite imagery of the Northeast showing relatively calm conditions and little in the way of cloud cover (Courtesy of Simuawips.com)

Some high clouds are possible Saturday evening as yet another series of weak mid-level disturbances pass to our north as well the south, but Sunday is shaping up to be very similar to Saturday with yet another beautiful day in store. Temperatures in the immediate New York metro area should be able to reach well into the 50’s, with southern locations once again seeing temperatures 10-20 degrees above normal as they climb into the low 60’s by late afternoon on Sunday. As we progress later into the day Sunday, a backdoor cold front will swing through the northern sections of our area and begin to usher in a more seasonable airmass as winds begin to shift from the south, to a more west/northwest. As this front continues on, we can expect a cooler day for Presidents Day Monday with a sharp temperature gradient from north to south across the area, with southern locations remaining in the low 50’s and 40’s for the northern locations. Overall, Presidents Day should be cooler than this weekend, but should remain dry and with very little cloud cover as a high pressure system from southern Canada begins to build south over the area providing continued calm/dry conditions once again.

Afternoon European model showing temperatures on Sunday reaching 18-25 degrees above normal for the entire area (Valid 1pm Sunday)

Afternoon European model showing temperatures on Sunday reaching 18-25 degrees above normal for the entire area (Valid 1pm Sunday)

As we continue on into the work week next week, mid level ridging will increase once more so a return to above-normal temperatures is likely over the entire Northeast. As a series of mid to upper level disturbances work their way east from the very active Pacific jetstream, we can expected our first shot of rain on Wednesday with a more significant signal for precipitation showing up just in time for next weekend as a stronger system works it’s way into the central part of the country. While we’re currently in a period of unseasonable warmth, the potential does exist for a return to colder temperatures and a more active weather pattern later this month and into the first few weeks of March. Make sure to stay tuned for any and all updates over the next few days! 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.

Have a great Friday and an excellent Presidents Day Weekend!