Today has been a cool and calm day across much of the Mid-Atlantic, but this break will be short-lived as another system is poised to bring heavy rains and strong winds to our area over the next 72 hours! High pressure will usher in another round of cold next week, with mainly calm conditions expected throughout the week.
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.
The line of heavy snow squalls that we talked about back on Monday blasted their way through portions of the Northeast earlier this afternoon. These squalls produced a quick burst of very heavy snow and strong, gusty winds that created significantly reduced visibility to just a few feet in some locations. Numerous accidents were reported across Pennsylvania, New Jersey, and New York, with a large incident involving over 40 cars in Berks County, Pennsylvania. The squalls have since moved over the far eastern portions of Long Island and will continue to head quickly to the east before moving offshore.
The main story for this entire forecast period remains to be the long-awaited Arctic front associated with the tropospheric Polar Vortex . This front will move through the New York City metro area later this evening and into the overnight hours, causing temperatures to rapidly fall. Readings will fall into the teens for the entire area this evening before falling once more into the single digits overnight-with locations off to the north and west likely getting below zero! Winds will also be quite strong behind this Arctic front, with sustained winds of around 20 mph and gusts up to 45 mph. The combination of extremely cold low temperatures and strong winds will make for some dangerous wind chills tonight. Wind chill values of -10 to -15 will be quite common for the entire forecast area, with values as low as -20 to -25 for elevated locations of NW NJ!
NWS forecasted lows valid 7 AM Thursday. The circles show the potential for records to possibly be broken (WxBell)
Thursday morning will likely start off as the coldest day of the season, with temperatures in the single digits for the AM commute. High temperatures will gradually crawl back into the teens for most of the area with clear skies overhead, but wind chills will continue to make things feel more like -5F to -15F. High pressure will be building to our south during the afternoon hours tomorrow, allowing winds to gradually ease-off as we go deeper into the day. Deep northwesterly flow will continue to bring in a very dry, stable airmass over much of the Northeast leading to persistently clear skies into the evening hours. The deep “vortex” located off to our north will be gradually moving well to our north and east throughout the day tomorrow, leaving a very cold, but slightly modified airmass in place for tomorrow night. Lows will once again drop into the low teens to single digits across much of the area, which will still be well-below normal for this time of year.
Cold, calm, and clear conditions will extend into Friday as high pressure builds over the East. We may have to watch a very weak shortwave trough near the Great Lakes that will be rapidly moving to the south and east during the day. An area of light snow may break out over portions of the Mid-Atlantic on Friday afternoon, but this is expected to stay to the south of the NYC metro area-with only some increased clouds expected for our area. Highs on Friday won’t be as brutal as Thursday, with lower to middle 20’s expected for the NYC metro, and teens likely off to the north and west. Lows will fall back into the teens to single digits once again on Friday night, making for a rather cold end to the week.
Loop of the high resolution NAM model showing the progression of dangerously cold temperatures through Thursday
A significant warm-up seems to be in the cards as early as Monday/Tuesday as another storm system off to our west cuts into the Northern Plains. Like the numerous storm systems that have done so this winter, this system will cause deep southwesterly flow to overspread the area. This will bring a return to highs in the lower to middle 40’s as early as Monday, with highs possibly getting into the 50’s by Tuesday!
The “warmer” pattern will be in place at least through the middle of next week as yet another strong Pacific disturbance carves out a trough in the West, leading to a large area of mid level ridging over the East Coast. At this time it appears that the threat of any major precipitation events are quite low, but there are some indications that conditions will turn wet by Wednesday/Thursday with another system cutting well off to our north and west.
This afternoon’s ECMWF run showing a deep trough located over the west and building ridge over the East. Such a pattern would favor a return to above average temperatures in the East
We’ll have an update on Friday taking a look at this weekend!
Have a great night
-Steve Copertino
Calm Conditions Persist Through the Weekend
High pressure will continue to build to the east during the early morning hours of Saturday, causing any remaining gusty/breezy conditions to subside significantly. Partly cloudy skies and cooler temperatures are expected to prevail into the afternoon hours, with highs likely getting back into the lower to middle 30’s for the entire forecast area. By Saturday evening, a large upper level low situated over portions of southern Canada is expected to begin to move to the south. This will set up a more southwesterly flow over the area into the overnight hours. While the mid level airmass source region will be different than this evening’s, clearing skies and relatively dry conditions throughout much of the lower to middle levels of the atmosphere should allow for robust radiational cooling to take place. This will still cause lows to drop into the upper teens to lower 20’s Saturday night-which will once again be below normal across the area.
By Sunday morning the large and impressive upper level system just to the north of the Great Lakes will continue to shift to the south and east, spawning a surface low pressure system well to the north of our area. While direct impacts in the form of precipitation are unlikely from this low pressure area, it will help to increase low to mid level clouds over much of the Northeast. Additionally, this surface low to our northwest will also increase southerly winds over the area, leading to slightly warmer highs during the day. Temperatures should be able to reach back into the lower to middle 40’s across much of the NYC area, with upper 30’s likely across the interior-which will be on the order of 5-10 degrees above normal. Finally, a cold front associated with the area of low pressure to our north will move through during the evening and overnight hours of Sunday. At this time it appears that the cold front will likely be significantly lacking in moisture, making this frontal passage a dry one. The front will also usher in colder middle to lower level temperatures once again, bringing lows back down into the lower to middle 20’s.
This evenings NAM model showing the progression of warmer surface temperatures into Sunday, followed by another cold front Sunday night (COD Weather)
As we highlighted back in our last update, another northern stream shortwave trough will be heading into the Northern Plains by Monday morning that bears watching.
This system will be pushed well to the south by Monday evening as a deep upper level system that is directly associated with the tropospheric polar vortex makes its way into Southern Canada. As this deep and highly-anomalous system continues it’s push into Southern Canada on Tuesday, precipitation will likely break out over portions of the Southeast and extending up into the Ohio Valley along a frontal boundary. As this boundary approaches the Northeast by Tuesday night, large scale upper level divergence will be on the increase over much of the East Coast. This would support the development of a quickly intensifying low pressure system near or over the Northeast late Tuesday and into early Wednesday morning-but this is where the reliable model guidance begins to diverge.
This afternoon’s European model showed a substantial amount of energy swinging through the Mid-Atlantic states, causing the development of a rapidly intensifying surface low that moves inland over portions New England by Wednesday morning. Such a solution would bring some light rain/snow during the onset, with a quick flip to more significant mixed precipitation as the low pressure rapidly strengthen and drags in much colder air from the northwest. The rest of this afternoons guidance does indeed show a low pressure system forming along the frontal boundary, but disagree on the exact location and magnitude of deepening of this potential system. Needless to say, these factors will play a major role in determining the overall outcome of this system.
At this time, even a compromise of these solutions (weaker vs. stronger) would bring the potential for some impactful weather to the area Tuesday/Wednesday AM. We will need to closely monitor this system over the next few days as new data comes in.
12z European Ensembles showing a significant amount of members developing a strong secondary area of low pressure over the Northeast on Wednesday AM (WxBell)
Regardless of what the Tuesday/Wednesday system does, virtually all available model guidance and their respective ensembles agree that the westernmost lobe of the tropospheric polar vortex will swing into the Northern Plains and Great Lakes by Wednesday night. This will cause a very impressive Arctic airmass to blast its way into the northern tier of the country-with potentially record breaking temperatures for the Great Lakes region. As this Arctic airmass heads into the Northeast, early indications are that it may begin to moderate just enough that portions of the Northeast are spared from record cold. However, the potential will certainly be there for an extremely cold end to next week with high temperatures struggling to break out of the single digits, in addition to dangerous wind chills well-below zero.
Diagram showing an Arctic high pressure system moving into the Central US during the middle of next week, dumping extremely cold temperatures into the CONUS (White colors denote areas that are below 0F)
We’ll continue to update you on this Arctic outbreak as well as the potential storm system for mid-week!
Have a great weekend!
-Steven Copertino