Updated: Mild and calm conditions turn unsettled later this week
Good evening!
The short-lived, but intense blast of Arctic air last week is now all but a memory as an area of mid-level ridging continues to build over much of the East Coast.
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Mild and Calm Conditions Take Hold, Watching a Potential Coastal Storm for Friday
Good evening!
After the cool and dreary conditions over the past couple of days, today was a slight improvement for much of the Northeast as a cold front gradually passed through the region, signaling a change to the sensible weather pattern. This front was luckily rather tame in nature, as the energy associated with the front was strung-out and not well-organized. This allowed for only moderate changes to gradually take place during the course of the day, with a rather cloudy and cool start to the day. As the day continued on, we saw high to mid level clouds lessen with time, eventually giving way to some peaks of sun. Winds shifted to the northwest behind the front, with more dry and cool air filtering into the Northeast. Modest cloud cover and a renewed airmass from Canada kept temperatures in check, with highs ranging from the lower to upper 40’s, with some locations reaching the 50 degree mark. Dry air from the north and west should continue to mix out any residual low level moisture over the next 6-12 hours, leading to mostly clear skies this evening. Additionally, an area of high pressure will be building in over the Mid Atlantic and Northeast tonight, so expect any winds to gradually diminish over time. These conditions will be quite favorable for radiational cooling to take place overnight, with temperatures likely dropping quite a bit into the lower to middle 30’s over much of the area. Some locations off to the north and west will likely drop into the middle 20’s this evening, causing any residual moisture on roadways to freeze, so please watch out for slick patches if you’re driving tonight.
This evenings latest high resolution water vapor imagery, surface observations, and surface winds, showing a more calm temporarily setting up.
Tuesday through Thursday
Tuesday will likely start off quite chilly, but clear as the area of high pressure continues to build and move eastward with time tomorrow morning. Conditions will be quite dry throughout the majority of the atmosphere, so skies will likely remain mostly sunny for the majority of the day, with a few upper level cirrus clouds passing through. The fresh Canadian airmass in place in combination with the high pressure will work in tandem to keep conditions cool, but not too cool over the entire Northeast. Highs tomorrow afternoon should remain in the middle to upper 40’s, with some inland locations likely hitting the 50 degree mark again. All in all, tomorrow should be a rather nice day, but will likely still require a light jacket to stay comfortable. Tomorrow night looks to be calm and cool as well, but not quite as cool as tonight. Lows will likely dip down into the middle to upper 30’s for the majority of the Northeast, with some locations possibly just getting below freezing.
Wednesday looks to be one of the more mild days of the week as the area of high pressure that has been dominating the east begins to move off the Mid Atlantic coast. This should create more southerly flow in the mid to low levels of the atmosphere, bringing in slightly warmer highs for the afternoon hours. Moisture looks to also increase with the southerly flow as a shortwave trough digs into the desert southwest, sending some residual energy into the east. This energy out ahead of the main system should allow for some clouds and even a few isolated showers to develop in the late afternoon hours, but not significant rain is expected. Highs will likely be able to rise into the lower to middle 50’s across the vast majority of the Northeast. Cloudy conditions will likely continue throughout the overnight hours, with the threat of a couple of showers lasting into the early morning hours. Cloud cover and southerly winds should keep lows from dipping too much, with readings likely staying in the middle to upper 30’s-with some locations seeing lows in the lower 40’s.
Things begin to get a little more interesting on Thursday, as the system that was in the southwest begins to move into the Plains and interacts with another shortwave coming down from Canada. As these systems interact and attempt to phase, a primary surface low pressure system should form over the Great Lakes region, with a large area of rain expected over much of the Southeast. As this low moves closer to the Northeast, cloudiness will likely increase in addition to the threat of some showers as we head into the late afternoon hours. Later in the evening, this area of low pressure should continue to intensify, as the mid level system becomes much more organized. This process should continue into the overnight hours, as a stationary front likely sets up over the Mid Atlantic, which may become the focus for a secondary low pressure system to form. Temperatures on Thursday will likely remain mild, with highs in the lower to middle 50’s over the entire Northeast.
This evenings NAM model showing the development of a potentially impactful system for the Northeast
Potentially Impactful Coastal System Shaping up for Friday
This afternoons model guidance continues to show the potential for the primary low pressure system that travels over the Ohio Valley to redevelop just off the Mid Atlantic coast early Friday morning, but there are still a large amount of uncertainties with this forecast. Regardless, what we do know is that an area of blocking will be located over Greenland, which will act to slow down the mid level system and allow it to strengthen as it nears the coast. This should lead to the development of a strong low pressure system adjacent to the Mid Atlantic coast during the day on Friday, likely leading to a wide range of impacts. Almost all of the model guidance shows an impressive swath of winds just above the surface with this system due to a tight pressure gradient. Additionally, this system will be capable of tapping moist air from the south, so it will likely have a good amount of moisture to work with, leading to the development of widespread moderate to heavy precipitation. Lastly, winds out over the ocean will likely be directed towards the coast, which will create at least a moderate threat of coastal flooding as we enter a full-moon phase. One of the main things we do not know at this time is exactly when and how much phasing will occur with the two original disturbances over the Ohio Valley. A quicker phase would lead to a stronger coastal low tucked right along the coast, while less/delayed phasing will likely lead to a weaker and more elongated system.
There is also the question of precipitation type, which is something that seems to be highly sensitive at this time. While a stronger system would be able to create enough dynamic cooling for some snow to fall, this solution would also mean that the primary low in the Great Lakes sticks around longer, which creates more warm air for the coastal plain. At this time it does not seem like a widespread significant snowfall is likely from this system, but there could be some locally heavy snow in the higher terrains of the Northeast if conditions line up correctly. We will be keeping a very close eye on this system this week and will continue to provide updates as they become available!
This afternoons European ensemble individual members showing a wide variety of solutions for Friday’s system
Have a great night!
Steve Copertino
Record Cold Quickly Departs, Potentially Stormy Pattern Setting Up In the Long Range?
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
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.
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.
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Have a great night!
Steve Copertino
Cooler Conditions Finally Take Over, But Will They Last?
Good Evening!
A cold front moved through sections of the Northeast late last night, bringing areas of showers, gusty winds, and more importantly a sizable airmass change. Within a period of only a few hours, the cold front knocked us into more autumnal conditions, with dewpoints dropping from the unusually high low to middle 60’s, back into the low 30’s-leading to a much more crisp feeling to the air today. Additionally, cooler temperatures aloft have left the entire area with much cooler highs as well, with most of the Northeast seeing highs in the middle 50’s to lower 60’s, with even a few areas in Pennsylvania and New York seeing temperatures stuck in the upper 40’s. Conditions have also become quite windy across the area behind the cold front-with many stations reporting northwesterly winds gusting in the 20-30 mph range through the afternoon and into the early evening hours. This northwesterly flow has also worked to bring in cooler air over the relatively warm Great Lakes, which has generated some lake-effect clouds this afternoon that has mainly been focused over New York state, with some low-topped cumulus clouds over Pennsylvania. Further east over the metro area, we’ve seen a mix of sun and clouds over the area as some trailing upper level cirrus clouds quickly move from southwest to northeast on the eastern side of the upper level trough.
As we head into sundown, gusty conditions will likely remain in place for most of the area, except for portions of central Pennsylvania and western New York. The cirrus deck that has been in place most of the day will continue to diminish over the next few hours and head off to the east as the upper level trough continues to lift out. This will allow for skies to become quite clear this evening, and with low humidity, clear skies, and diminishing winds, we will have at least marginal conditions in place for radiational cooling to take over. Temperatures will likely fall into the “cold” levels this evening as lows dip down to the upper 30’s and lower 40’s for the immediate NYC metro area. Further north and west, lows could get into the low to middle 30’s, which could cause patchy frost to develop in the areas that see the wind really calm down over the next few hours. The NWS has issued numerous Frost advisories over the Northeast, so make sure to bring in any plants that may be vulnerable to frost conditions this evening.
Tuesday will likely be another calm and cool day for the Northeast as surface high pressure begins to build in from the south and west by tomorrow afternoon. Highs will likely range from the upper 50’s to lower 60’s, with areas further north and west likely seeing readings a few degrees lower. Humidity will also remain very low tomorrow, and though this may feel like its a big deviation from the normal, but tomorrows highs will likely be right around seasonable for this time of year. The building high pressure will allow for lows tomorrow night to fall back into the low to middle 40’s tomorrow evening, and with lower overall winds patchy frost may be more likely across the area.
3km NAM showing much cooler conditions overall for the Northeast
Later This Week and Beyond
As we look ahead into the later part of the week and past the weekend, we are likely to see mid level ridging rebuilding over the east by Thursday, which should lead to a small increase in highs for a coupel of days. We should be looking at temperatures rising into the low to middle 70’s pretty much every day for the rest of the week, and then again this weekend as a second area of mid level ridging begins to build into the East by Saturday. This pattern should last us into the early to middle part of next week, before the overall pattern begins to shift largely due in part to large scale convective patterns in the tropics becoming more concentrated in this area of the globe. When this happens, we tend to see a large area of riding set up over the western United States, with a trough eventually setting up in the east. Such a scenarios would be a large departure from the normal over the past few weeks of warm and dry weather, as the eastern trough would likely bring below-average temperatures and an increased rain potential during the period. While the individual model runs seem to disagree about the exact timing of when a coherent area of troughing will set up over the east, the ensembles have been rather consistent that around the October 24th-28th period, the likelihood for this scenario is high.
Due to the level of enhanced convection over the tropics during this time as well in conjunction with leftover warm waters over the Atlantic, we may also have to keep an eye on the tropics to see if we can manage to get a late season storm out of this pattern.
We will have more on this pattern later in the week!
ECMWF Ensembles showing a deepening trough beginning to set up over the east by the middle 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