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Steven Copertino

Record Cold Quickly Departs, Potentially Stormy Pattern Setting Up In the Long Range?

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Good Afternoon! 

The Arctic front that we have been talking about for around a week now has finally cleared the entire Northeast, leaving well-below normal temperatures in its wake. Earlier this morning, the front blasted through the region with some rain and snow showers, some of which were heavy up towards the central locations of upstate New York. These showers were quickly undercut by much more dry and dense Arctic air from Canada and promptly dissipated. Todays high temperatures were actually set in the early morning hours just ahead of then cold front, with most locations peaking in the lower to middle 40’s. After the front blasted through, temperatures promptly dropped a good ten to fifteen degrees across the entire area, with temperatures in the upper 20’s to lower 30’s being reported from most stations. Temperatures just behind the front change quite a bit with height, which has allowed stronger low level winds to mix down to the surface and cause conditions to become quite blustery, with gusts in the 25-35 mph range this afternoon. This has allowed for wind chills in the metro area to fall into the lower 20’s and teens. As mentioned earlier. the Arctic air has brought in a significantly drier airmass, so any shower activity into this evening will be confined to locations near the Great lakes, where the temperature differential will support the growth of some gusty snow squalls.

The area are of low pressure that brought the Arctic front through the area begins to occlude and weaken while pulling east, the pressure gradient between the Arctic high and the low pressure will decrease significantly, leading to winds steadily decreasing by sunset. As the winds calm and high pressure takes over, we should have near-ideal conditions for steep radiational cooling to take place across the entire Northeast. This will mean that lows will quickly drop off into the teens and even single digits for locations off to the north and west. These temperatures will likely break record lows for many stations across the Northeast, with some readings likely being 15-30 degrees below-normal for this time of year! Any locations that have not yet had their first freeze this Fall will certainly experience a hard freeze this evening, with any vulnerable plants quickly succumbing to the below-freezing temperatures.

RTMA temperatures showing the near-record cold readings across the area in conjunction with the gusty winds behind the Arctic front

RTMA temperatures showing the near-record cold readings across the area in conjunction with the gusty winds behind the Arctic front

Saturday morning should start off quite cold and clear with the area of high pressure developing right over the Northeast. Winds will likely be much calmer than they are this afternoon, so we may start off a little more pleasant than originally thought. Mid level temperatures will begin to increase a bit, but still be cold enough that much of the Northeast experiences somewhat below normal temperatures tomorrow with highs likely staying in the middle to upper 30’s, with some locations hitting the 40-degree mark. The day as a whole should be relatively calm as a more west-east oriented jet stream sets up aloft, which should shift winds to the east/northeast as the day goes on. Later in the evening, the area of high pressure should be located just offshore of the Mid Atlantic coast, which will be the area more of an onshore flow. This could cause some low level moisture to work into coastal sections of NJ, CT, and NY, but the very low dewpoints in place may keep much of this marine airmass at bay. Regardless, expect another cold night with lows likely dropping back down into the lower 30’s and upper 20’s farther north and west, where radiational cooling will be prevalent. As a side note, the somewhat increased moisture and calm winds may allow for patchy frost to develop, especially across the interior.

High pressure will likely still remain just offshore by Sunday morning, with clear skies and cool temperatures likely. As we head into the afternoon hours of Sunday, a weak disturbance will be caught in the very quick west to east oriented jet stream that we talked about. Without any kind of blocking to slow this system down and let it organize, it will likely remain sheared out and weak as it nears the area later in the day on Sunday and Sunday night. This disturbance will likely cause a slight increase in temperatures during the day Sunday, with hgihs likely hitting the lower to middle 40’s. An increase in clouds is also expected as the day goes on Sunday afternoon, with some light showers possible across the southern locations of the Northeast and Mid Atlantic states.

This afternoons ECMWF model showing the very quick west to east positioned jet stream. This pattern has no blocking to slow down any mid level disturbances to allow them to organize and strengthen.

This afternoons ECMWF model showing the very quick west to east positioned jet stream. This pattern has no blocking to slow down any mid level disturbances to allow them to organize and strengthen.

As we head into the beginning of next week, the west to east jet stream will likely stick around,  allowing for a large area of mid level ridging to develop across the Central part of the United States and into southern Canada. This should bring temperatures up a bit, with highs likely rebounding back into the upper 40’s and 50’s through Wednesday or so. This area of riding and quick mid to upper level flow will also prevent any major rain events in the medium range, so expect at least the first half of next week to remain calm and dry.

Long Range

As we get deeper into next week, we may see a pattern shift towards more blocking near Greenland, which would not only slow down the flow across the country, but also allow for below-normal temperatures to start to creep back into the country. The models and their ensembles have been keying in on this type of blocking pattern to set up for about a week now, and things may kick off as early as next weekend. In addition to the blocking near Greendland, some higher heights over the North Pole may also help to drain cold air southward by next weekend and beyond, which could allow for cooler temperatures and even a few wintry precipitation events to exist near the Thanksgiving time period over the Northeast. While this has been advertised for a while on a variety of the models, this is still over a week out and things could very quickly change due to the chaotic nature of the jet stream over the  Pacific. Regardless, we expect an increased chance for below average temperatures and above-normal precipitation over the east starting the end of next week and heading into Thanksgiving. This is a developing pattern, so make sure to check back for further updates!

Long Range ECMWF Ensembles centered on next weekend illustrating an active pattern with potential cold air intrusion.

Long Range ECMWF Ensembles centered on next weekend illustrating an active pattern with potential cold air intrusion.

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Have a great night!

Steve Copertino 

Steven Copertino

First Major Arctic Intrusion of the Season Blasting South

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Good Evening! 

Today was another in a developing string of cooler days after the system that produced some of the first frozen precipitation of the season quickly scooted east. Behind this system, an expansive area of high pressure has slid in and strengthened over Pennsylvania and other surrounding states. This area of high pressure has allowed for drier conditions for the duration of the day, but has also allowed for cooler temperatures aloft to move in as well. The combination of the cooler temperatures aloft and mostly cloudy skies allowed for highs to only get into the middle 40’s to lower 50’s today across much of the New York metro. These cool and calm conditions should last through the night as the area of high pressure continues to move eastward. The combination of light winds, cold mid level temperatures, and relatively clear skies should allow for decent conditions for traditional cooling to take place. This will permit lows dropping into the middle to upper 30’s, with some locations to the north and west of the coast likely seeing lows dipping down into the upper 20’s. If you still have any plants outside that are not able to handle hard freezes, then tonight may be the last chance to take any plants indoors before much colder temperatures arrive.

Real time temperature analysis , surface observations, and regional radar showing a calm, but cold end to our Wednesday

Real time temperature analysis , surface observations, and regional radar showing a calm, but cold end to our Wednesday

Thursday Into This Weekend 

By Thursday, the large Arctic trough that we have been talking about since last week will the located across the northern section of the country after diving south from deep in Canada. Low level flow out ahead of this deep trough will be out of the southwest, which should be able to advect some warmer air from the south over the Northeast and over the I-95 corridor. Despite the southwesterly flow, dry air aloft is expected to keep much of the area dry and relatively cloud-free during the day. This should allow temperatures to warm just a bit to the upper 40’s and lower 50’s across much of the New York metro, with some locations near the coast likely seeing highs rise into the middle 50’s. Though, as the day progresses, the strong Arctic front will rapidly breach the Northeast United States. We may see clouds begin to increase due to the enhanced low level moisture interacting with some cooler temps just ahead of the front, and this may even spark a shower or two over the area very late tomorrow and into the early morning hours of Friday.

Friday should see the full brunt of this Arctic front starting very early in the morning, with the boundary likely clearing the NYC area before dawn. We may see a situation on Friday where the early morning temperatures that take place before the front arrives are actually the highs for the day, with temperatures steadily dropping thereafter. Behind the Arctic blast, skies will likely be partly cloudy, with some locations possibly evening seeing some bursts of snow as moisture streams off of the Great Lakes, which are still quite warm. Winds will also begin to pick up during the day, with gusts likely in the 20-25 mph range. With Fridays highs likely being set in the very early morning, afternoon temperatures should drop into the lower to middle 30’s, with wind chills likely in the teens and 20’s. Friday night will be the coldest night the Northeast has seen since earlier this winter, with overnight lows dropping into the teens and lower 20’s and windchill’s dropping into the single-digits and teens! These temperatures will be more akin to January than November, and will likely be 15-25 degrees below normal across the entire Northeast!

Loop of the Arctic front blasting through the Northeast Thurs PM/ Fri AM

Loop of the Arctic front blasting through the Northeast Thurs PM/ Fri AM

Temperatures will remain very cold into Saturday morning as the core of the area of high pressure begins to pass overhead. This should allow for clear skies on Saturday with diminishing winds. Highs will likely be only a few degrees warmer, with temperatures unlikely to escape the 30’s across much of the region, with the exception of coastal locations. Overnight lows will likely drop past the freezing mark once again as clear skies and cold mid level temperatures dominate the evening. Expect lows in the lower to upper 20’s with coastal sections once again seeing slightly warmer temperatures.

By Sunday, things should warm up into the 40’s  ahead of an approaching storm system that will likely be located in the central US and Ohio valley. Sunday should feature This area of low pressure will also increase low level moisture, so expect clouds to develop later in the day, with a chance at some cold showers by the overnight hours.

This system could potentially bring some moderate rain to the Northeast on Monday and Tuesday with an increase in temperatures, but model guidance diverges significantly on this solution at the moment, and we will have much more on this potential system by the end of the week!

This afternoons ECMWF model showing a potential coastal storm for the beginning of the work week next week

This afternoons ECMWF model showing a potential coastal storm for the beginning of the work week next week

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Have a great night!

Steve Copertino 

Steven Copertino

Major Air Mass Change This Week, First Flakes Possible!

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Good Evening! 

Well we hope that all of you have been enjoying the relatively warm temperatures over the past few weeks, because it looks like things are about to change in a big way over the next few days across the entire east. Today was the last in the series of warmer days across the Northeast as an area of low pressure moved eastward across New York state. Southwesterly flow at the surface allowed warmer mid level temperatures to funnel in, as well as some leftover moisture from yesterdays severe weather outbreak over the Ohio Valley. This moisture was responsible for producing some clouds and showers over much of the Northeast, but much of the rain was on the light to moderate side of things. Despite these clouds and showers, temperatures were able to head into the middle to upper 60’s, with some locations in southern New Jersey actually reaching the 70 degree mark once again! The area of low pressure moving to the north of the New York Metro area has a rather strong cold front associated with it, and is currently moving over Pennsylvania and into portions of New Jersey. Winds have begun to shift to a more westerly/northwesterly component, which will mark the beginning of cooler temperatures and lower dew points leaking into the region.

Any leftover showers will quickly head east and dissipate over the next few hours, and this should give way to more clear conditions as we head into the night. An increasing pressure gradient from an area of high pressure building to our west will begin to create some gustier winds from the north, which should range in the 15-20 mph area. Overall, lows this evening will likely drop into the upper 30’s and lower 40’s across much of the area, with some middle 30’s possible in the interior locations of NJ, PA, and NY.

RTMA temperature analysis, surface observations, and regional radar mosaic showing the progression of relatively strong cold front moving through the area this evening (Simuawips)

RTMA temperature analysis, surface observations, and regional radar mosaic showing the progression of relatively strong cold front moving through the area this evening (Simuawips)

Tuesday Into Wednesday 

Tuesday morning should start off quite chilly, with some gusty winds still sticking around at least through the morning commute. The area of high pressure moving eastward will likley keep the majority of the day quite clear and calm, with highs generally in the lower 50’s across much of the New York metro area-though lower temperatures will likely be found to the north and west. The main story for tomorrow will be a weak wave of low pressure moving along the leftover cold front that will be located over portions of the southern Mid Atlantic states by tomorrow afternoon. As this system quickly slides along the front tomorrow, it should bring an area of light to moderate rain over portions of the Mid Atlantic states like Maryland, Delaware and Virginia by 5-7 pm. The northern fringes of this weak system will likely also impact the New York Metro area as well, but this setup will be especially interesting to watch for those located in NW New Jersey, NE Pennsylvania, southern New York, as well as the higher elevations of Connecticut as the wave of low pressure begins to head off the coast. As the system moves off the Delmarva late Tuesday and into the very early morning hours of Wednesday, the system will begin to strengthen just a bit, and this should help to cause a more uniform wind pattern at the surface, which could be capable of tapping the new/colder Canadian air just to the north.

This evenings NAM model, a colder solution, showing snow mixing in on the NW fringes of the precipitation tomorrow evening

This evenings NAM model, a colder solution, showing snow mixing in on the NW fringes of the precipitation tomorrow evening

Some of the higher resolution models have just enough cold air filtering in at the lower levels of the atmosphere, that we will indeed have to watch for a mix to possible changeover to snow across portions of Northeastern Pennsylvania, Northwestern New Jersey, southern New York, and Connecticut around midnight. While the thermal profiles of today’s models do show a good chance at a mix of wet snow/rain, there also could be some graupel mixed in as well, making roads a bit slick for any persons traveling. Precipitation should be light enough in these locations that any wet snow that does fall will likely melt on impact with the ground, but if the cooler solutions of the other models verify, there could be some locations well to the north and west of the city that wake up with a trace of wet snow in the grass that melts away by the morning commute. Further south and east, this event looks to be mainly a “33 and rain” type of event, where there just isn’t enough low level cold to support anything but light rain with little fanfare. Lows tomorrow night will be rather cold, with temperatures ranging from the lower to upper 30’s-with warmer temperatures located near the coast.

This system will quickly move away by Wednesday morning, leaving some high clouds and light winds in its wake. A very weak area of high pressure will try to build over portions of Pennsylvania during the day, which should keep winds light, and skies clear for the rest of the day. Temperatures will be on the cool side for highs, with most of the Northeast likely staying in the upper 40’s to lower 50’s. Lows will be quite cool as well, as conditions set up for radiational  cooling to take place, so expect temperatures to drop into the lower to middle 30’s-with warmer lows closer to the coast.

This afternoons GFS model showing a very impressive cold shot blasting through the Northeast on Friday and into Saturday morning

This afternoons GFS model showing a very impressive cold shot blasting through the Northeast on Friday and into Saturday morning

Thursday and Beyond 

By Thursday, a strong upper level trough will be moving east over Canada, carrying very cold air with it from the northern regions of Canada. This cold and dense Canadian air will begin to sink south into the Northeast in the form of an Arctic front. This front should quickly move through the region late Thursday, bringing lows in the 20’s and 30’s, with a shot at some snow showers across the entire Northeast. This cold shot should last into Friday evening, where lows may drop well into the 20’s. Temperatures will moderate a bit by Sunday, but should stay somewhat below-normal.

12z ECMWF overnight lows Friday PM/Saturday AM

12z ECMWF overnight lows Friday PM/Saturday AM

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Have a great night!

Steve Copertino 

Steven Copertino

Weekend of Unsettled Conditions and Temperature Swings, Potential Cool Shot Next Week?

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Good Evening! 

Today has has been a rather decent end to the work week with above-normal temperatures and light winds from the east. A warm front moved through the region the other night and introduced much warmer temperatures and higher dewpoints across much of the Northeast. This increased moisture from the southwesterly flow also allowed for more clouds to develop as well, but this did not stop highs from reaching into the middle 60’s to middle 70’s, which is a good deal above normal for this time of year. However, changes are on the way this evening, with a cold front currently located moving through central Pennsylvania. While this cold front isn’t all that strong, it will be strong enough to drop temperatures later tonight as well as knock dew points down to more seasonable levels. Additional, high pressure will begin to build in behind this front, so this will set up a strong enough pressure-gradient to create some gusty winds in the 15-25 mph range late tonight and into early tomorrow morning. Temperatures should be able to drop into the lower to middle 40’s tonight, with locations more north and west of the city likely seeing lows in the middle to upper 30’s. while conditions would otherwise be quite favorable for radiational cooling and some frost, the potential for gusty winds across the area should limit both of those possibilities.

High resolution visible satellite imagery, surface observations, and regional radar mosaic (Courtesy of SimuAWIPS)

High resolution visible satellite imagery, surface observations, and regional radar mosaic (Courtesy of SimuAWIPS)

Saturday Into Sunday

Saturday should have a nice and crisp start to the day as the northwesterly flow from Canada kicks in over the Northeast with winds still gusting in the 15-20 mph range. High pressure will also continue to build over the area, which should help promote sunnier skies and calm weather during the first half of the day. As we move deeper into the day tomorrow, winds should gradually shift from northerly to easterly, which will signify the start of another warm from passage. Dewpoints will also begin to increase once again as marine air works its way west, which will also work to gradually increase clouds by the late afternoon hours. Highs will likely reach the middle to upper 50’s tomorrow, with some locations closer to the coast likely making it to the 60’s. As the warm front begins to work its way inland, some weak low level energy will be present, which may help to increase the threat of showers across the area. These conditions should last into the evening hours, with lows staying in the middle to upper 40’s-some locations closer to the coast will likely be stuck in the 50’s due to warmer marine air aloft.

Sunday should start off quite the opposite of how Saturday did, as an approaching mid level warm front will increase moisture and available lift. This will cause an increased threat for showers, especially across western New Jersey and portions of eastern Pennsylvania. The overall progression of the front is still in question, but Sunday certainly looks to be quite a few degrees warmer than the previous day, with highs making it up into the middle to upper 60’s, which will be above average once again despite the increased threat for showers and cloudiness. Lows will likely stay rather mild with temperatures dipping into the upper 40’s and lower 50’s.

This afternoons high resolution NAM model showing showers located over eastern PA and potions of NJ early Sunday morning

This afternoons high resolution NAM model showing showers located over eastern PA and potions of NJ early Sunday morning

A Look Into Next Week

By Monday, most of the Northeast should be well within the warm sector of the warm front, so expect warmer temperatures once again for the region, with 70’s quite likely-which will be a good deal above normal. Later in the day on Monday, an area of energy associated with a trough in southern Canada will be moving our area and will enhance southwesterly flow ahead of an approaching cold front. While this front will be weakening quite a bit from when it moves on in from the Ohio Valley, it certainly will have the potential to bring some showers later in the day as it approaches the coast. As the front pushes offshore by Monday evening, dry northwesterly winds will once again take over and provide a chillier airmass for the entire Northeast as Canadian high pressure builds in.

Conditions will then turn rather zonal from Tuesday until Thursday, with the jetstream generally blowing from west to east across the nation. This should allow the area of high pressure to stick around for a majority of the week, with mainly dry conditions expected over the region. Temperatures should generally stay near-normal during this period as cooler air from Canada bleeds south ever-so-slightly. Thursday may have a shot at rather cold lows as an approaching trough from Canada starts to move southward.

By Friday, things begin to get interesting as the models have been keying in on a deep trough moving in over the East and bringing a nice shot of unseasonably cold weather. Western ridging will improve just enough to allow the cold that has been trapped to our north to quickly come down south by Friday night in the form of an arctic front, which will likely drop lows below freezing across the entire zone, with some locations well off to the north and west seeing lows in the 20’s and even teens. Depending on how much low level moisture hangs around before this Arctic front moves through, some locations could actually see flurries or snow showers, but this is something that we will have to revisit next week. Regardless, the chances of a widespread freeze are increasing for the later part of next week.

This afternoons ECMWF model showing a sharp shot of cooler temperatures over the Northeast by the end of next week

This afternoons ECMWF model showing a sharp shot of cooler temperatures over the Northeast by the end of next week

For more information and posts like this one, make sure you sign up for Premium 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 night!

Steve Copertino