Unseasonably cold and dry conditions prevail, update on the snow threat this weekend
Good evening!
Today was quite the interesting day across the tri-state area as the area of low pressure that we have been talking about for the past few days developed off of the New Jersey coast early this morning. This area of low pressure was spawned by a mid-level disturbance that was able to organize just at the last second as it approached the Mid-Atlantic coast. As both the surface low and the mid-level system both organized this morning, a narrow area of snow broke out over portions of southern New Jersey. This area of snow quickly grew from east to west during the early afternoon hours, extending back into eastern Pennsylvania at its peak. The small, but impressive band of snow virtually stalled over Atlantic county and produced snowfall rates of up to 1.5″ an hour. At the time of this article the highest snowfall totals from southern New Jersey are in the 4-6″ range, but it would not be surprising at all to see a few isolated reports come in higher. Elsewhere, there was a rather steep gradient with accumulations mainly in the 1-3″ range to the north and south of the main axis of heavy snow.
This area of low pressure and the associated surface trough are now beginning to pull to the east, causing any residual snow along the coast to wind down. We should see this low continue off the coast this evening, with calm and decreasingly cloudy conditions through the overnight hours for the vast majority of the Northeast. Usually a storm pulling away from the coast would produce near-ideal conditions for radionatal cooling all the way to the coast, but there appears to be a chance that stubborn mid/upper level clouds will hang on just enough, at least for the immediate New York City area. Accordingly, lows will likely stay in the middle to upper 20’s tonight, with middle to lower 20’s likely for locations to the north and west.
Latest high resolution water vapor imagery, surface temperatures, surface winds, and regional radar showing the area of low pressure responsible for the NJ snow beginning to head east
Unseasonably cold and dry conditions to continue through the weekend
Thursday morning should start off like every other morning so far this week, with mostly sunny conditions and cold temperatures in the middle to upper 20’s for the AM commute. Clear and cold conditions should continue through the afternoon hours before a broad area of upper level energy approaches the region from the northwest. While this system should remain relatively dry given the fact the associated airmass is continental arctic, there may be just enough lift to spark the development of light to moderate snow showers towards the evening hours tomorrow night. While the bulk of this activity should stay over portions of New York state and Pennsylvania, it would not be all that surprising to see some narrow bands extend all the way back into portions of New Jersey and possibly even NYC. Otherwise, increasing cloudiness will put a lid on low temperatures tomorrow night, with temperatures likely staying in the middle to upper 20’s for the majority of the tri-state area.
By the time we get to Friday morning, yet another shot of cold/dry air will quickly move through the Northeast, likely clearing out any residual clouds from the previous night. Temperatures should stay in the upper 20’s to lower 30’s during the day on Friday, but occasionally gusty winds may make conditions feel a good 10-15 degrees cooler. Winds will likely calm down during the afternoon hours on Friday as an area of high pressure begins to edge into the East. With high pressure in control and all levels of the atmosphere very dry, we should see excellent conditions for radiational cooling to occur. Lows on Friday night will be quite cold, with readings dropping well into the 20’s, with teens likely for portions of NW New Jersey and southern New York. All in all, temperatures over the next few days will range anywhere from 5-15 degrees below normal across the entire Northeast, which is much more like January as opposed to early December.
Loop of the 18z 3km NAM showing unseasonably cold conditions persisting throughout the next few days.
Late weekend storm likely to stay south of the NYC area
Over the past five days or so we have been watching numerous pieces of energy in the atmosphere located over the Arctic, the Pacific, and Alaska which will likely interact with one another by the time we get to Saturday afternoon over the Southern Plains. As these pieces interact, a large area of heavy rain and snow will gradually develop and begin to produce a swath of significant snow that could extend from Oklahoma to the Mid-Atlantic coast when all is said and done. While we do know that these various pieces for the storm will likely come together, what we don’t have nailed down yet is exactly how and when they will do so.
As of right now, the most likely scenario is that the main upper level system over Texas will begin to strengthen during the day on Saturday, while another piece of energy from the Arctic dives into the Northern Plains, causing the main storm to speed up. Additionally, another area of energy will likely be located over Southeastern Canada, which will be injecting very dry air over portions of the Mid-Atlantic and Northeast. This dry air will essentially act as a wall during the day on Sunday as the main surface low moves through the Southeastern US and tries to make some northward progress. At this point, the forecast will be dependent on just how strong the disturbance over Southeast Canada is at the time. If the system is weaker, there is a chance that meaningful precipitation is able to make its way north and impact DC to Philadelphia. However, the model runs from this afternoon showed increased dry air and “confluence”, forcing the main impacts down into portions of KY, WV, VA, and NC.
While there is still time left before Saturday, we feel that there will likely not be significant enough changes with the predicted upper air pattern to cause any major changes with this forecast for the NYC area.
In summary, it appears increasingly likely that the immediate NYC area will remain well to the north of any potential impacts, with only increasing clouds and cold temperatures during the day on Sunday.
Current states at highest risk for significant winter weather impacts: KY, NC, SC, VA, WV
Current states at risk for some impactful winter weather, with high uncertainty: MD, DE, PA, NJ
Current states with lowest risk for impactful winter weather: NH, VT, ME, MA, CT, NY, RI
51-member ensemble from the European model showing the probability of 3″ or greater of snow. At this time significant impacts from this system are quite low.
Make sure to check back in during the day tomorrow for more updates on this system!
Steve Copertino
