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Blizzard conditions return to Freehold and Monmouth County
A significant winter storm is beginning to develop over the Gulf Coast that will bring the entire forecast area heavy snowfall and very strong winds. The most significant impacts will be focused towards the coastal plain once again, where many locations have experienced one of the snowiest winters of all time. This storm will likely push this year's snowfall totals to number one on the list, especially around central and southern New Jersey and Philadelphia.
This morning, the water vapor satellite image shows the developing upper level disturbances that will produce this dangerous winter storm. The Polar disturbance is diving towards the Ohio Valley with a weak surface representation over the northern Tennessee Valley. Meanwhile, the Sub Tropical disturbance is starting to tilt negative and beginning to phase with the Polar disturbance. The phasing of these two disturbances will create an intense upper level low over the Ohio Valley and then Virginia that will spawn a rapidly deepening coastal low tonight through tomorrow off the Mid Atlantic coast. The intensity of this low pressure will fall to below 980 MB possibly reaching 975 MB before exiting the New Jersey coastal waters. This intense low pressure system will have plenty of moisture to work with from the Sub Tropical jet stream and a well established and sustained Polar air mass over much of the Mid Atlantic.
At 500 MB, an intense upper level low will move towards northern Virginia with intense PVA or positive vorticity advection moving towards the New Jersey coast. Ahead of this upper low, there will be strong divergence from 500 MB up through 250 MB supporting an environment for rapidly rising air or lifting. Due to the upper low intensifying, the surface low will feel the "pull" of the upper low and slow down the low pressure system to a crawl off the Delaware and southern New Jersey coastal waters between 7 AM and 5 PM tomorrow before slowly exiting into the Atlantic in the evening hours. The influence of the upper low will lead to a prolonged period of moderate to heavy snow over the region as a result and support high snowfall totals.
The key to the forecast and the reason why I was hesitant to update much yesterday was the development of the 700 MB low. There is now strong agreement in the model guidance that the 700 MB low will track from the Ohio Valley through south-central Virginia and then exit south and east of New Jersey. The track of the 700 MB low is extremely important for this storm. This current forecasted track, which again has rather strong agreement in the guidance, keeps the rapidly developing dry slot to the south and east of the northern Mid Atlantic with the possible exception of extreme eastern Long Island. The track of the 700 MB low also puts much of the Philadelphia and southern New York City metropolitan area in an area of intense mid level forcing or lifting, which will likely support the development of various mesoscale features and keep the most intense precipitation over the region. Studies have shown that the heaviest snowfall usually occurs 100 to 150 miles northwest of the 700 MB low, which is exactly where much of the forecast area is located.
At 850 MB, a strong low level jet stream is going to develop off the New Jersey coast as the 850 MB passes south and east of the region. The strong low level jet stream will not only add significant Atlantic moisture to the developing coastal low pressure system, but also aid in supporting strong wind gusts over the region and intense mesoscale lifting. The thermal gradient will also become very intense. Some warmer air will work into southern New Jersey and eastern Long Island ahead of the 850 MB low, but otherwise the rest of the region will remain below freezing. By late Wednesday morning, 850 MB temperatures will crash well below freezing, creating an environment that will be highly unstable throughout the coastal plain. The combination of frontogenesis and this intensifying instability from the surface boundary layers to the mid level will create an environment highly supportive of convective snowfall, mesoscale banding, and there are some suggestions of an intense deformation zone developing on Wednesday evening as the storm exits. The combination of these factors will lead to the potential for some locations to have enhanced snowfall totals compared to surrounding locations.
The worst impacts from this storm will be focused along the coast once again, however even interior locations will feel the bite from this storm as moderate snowfall amounts are expected even up through the Hudson Valley. The worst conditions by far will be focused from southeastern Pennsylvania through much of New Jersey, the entire New York City metropolitan area and southern Connecticut. Due to the warm air mixing in along the immediate coast, accumulations will be lower along southeastern and eastern Long Island and southeastern New Jersey, however even these locations will have a significant impact from this storm. The strong wind gusts, potentially reach hurricane strength over the coastal waters, will create an environment of blizzard conditions with near zero visibility at times. This can not be understated! Even if a location accumulates 6 inches of snow, a strong wind of around 25 mph sustain will still keep visibilities on the low side. The worst conditions for this storm can be expected from 3 AM to 8 PM over the Philadelphia metro, 5 AM to 10 PM for the New York City metro, and 7 AM to 1 AM over eastern Long Island and eastern Connecticut.
Snowfall totals will be the highest over the Philadelphia metro through the New York City metro. The latest mesoscale guidance along with some analysis of the coastal front this morning suggests to me that the area from Monmouth County through Salem Counties have the best potential for convective snowfall including thunder snow due to the very unstable nature of the atmosphere and the combination of a very favorable alignment with the 850 MB low level jet stream. However all locations along the coast will have the potential to get into a mesoscale snow band that can enhance snowfall totals. Now, the issue with mesoscale features as always is that while one area can get hammered, another location to the east or west of that band can end up with significantly less snowfall than expected. That situation will have to be NOW-Casted, but the potential is certainly there for someone to exceed two feet especially if the deformation zone sets up over the region.
This storm is going to have a significant impact on the entire northern Mid Atlantic for both major rush hours. Due to this storm developing in the middle of the week, the impacts will be far more reaching than either major storms this year that occurred on the weekends. Travel will be impacted from this storm and individuals should be prepared for dangerous driving conditions tomorrow morning and tomorrow evening. In short, if you don't have to go out, don't!
After this storm exits, high pressure will take hold through the rest of the week with dry conditions and cold temperatures. Another potential snow threat is emerging for Sunday into Monday, however currently the majority of the precipitation will remain well to the south. For now, I'm advertising scattered snow showers.
Trust in NY NJ PA Weather for the latest analysis and live coverage of this dangerous winter storm!