Synopsis:
A stationary front has parked itself over the eastern seaboard creating a conveyor belt for moisture to ride up the east coast. A powerful disturbance will develop tonight and move into the region tomorrow creating heavy rain. The models indicate that the low will track up the western side of Appalachian mountains meaning that central third of the state will see the heaviest rain. This system will cause lingering showers through Thursday before high pressure takes back control of the region for the beginning of the weekend.
Short Term (through tomorrow night):
A low pressure system will approach the region from the southwest tonight. This low will develop in response to the cold front that passed through the region yesterday and that has subsequently stalled out over the eastern seaboard. Creating a height gradient along the gulf coast. (Classic winter storm set up!) Anyways, this low will be intense because not only is it on the eastern side of an upper level trough, it lies east of a large vorticity maximum. Not to mention the fact that they fall in the left exit and right entrance of two 300mb jet streaks that sit to its southwest and northeast respectively. Current model runs have the rain moving into Pennsylvania late tonight with steady rain developing tomorrow morning. The good news is that because the low is going to track on the western side of the Appalachian mountains, the entire state of Pennsylvania will reside in the lows warm sector keeping temperatures in the upper 40's and lower 50's. The bad news with this track is that the precipitation will train along the Appalachian mountains. The central part of the state will be hardest hit with rainfall totals frequently reaching over an inch with locally heavier rainfall possible by Wednesday morning. This is evident by the SREF 15z run.
Long Term (Wednesday through Friday):
Here is where it gets interesting because currently the models have a brief reprieve in the precipitation on Wednesday afternoon before the chance for showers returns Wednesday night and into Thursday as a shortwave vorticity maximum works it's way across the mid-Atlantic region. However, I am very skeptical of this. If you recall when I said that this set up is very similar to a classic winter storm system. Well typically, when the low tracks up the western side of the Appalachian with one of these systems, a secondary low will develop off the Mid-Atlantic coast and pound Northeastern portions of the state. If this occurs, then the NE, SE, NS, regions could see up to an additional inch of rain before this system gets pushed out of the region by the shortwave on Thursday. Currently the models aren't developing this secondary low, but I'd give it about a 30% chance of developing. So, make sure you watch it! The other thing of note is that behind this low, temperatures aloft will be falling below their critical values. This means that higher elevation areas could see a snow shower or two before everything is all said and done. High pressure will take the region back over on Friday creating sunny and cool conditions for the beginning of Thanksgiving Break!
Longer Range (Through early next week):
MREF 500mb height anomalies show a fairly nice ridge build over the north east through Tuesday so Thanksgiving Break should begin quite comfortably :-)
RJ Patrizio
A stationary front has parked itself over the eastern seaboard creating a conveyor belt for moisture to ride up the east coast. A powerful disturbance will develop tonight and move into the region tomorrow creating heavy rain. The models indicate that the low will track up the western side of Appalachian mountains meaning that central third of the state will see the heaviest rain. This system will cause lingering showers through Thursday before high pressure takes back control of the region for the beginning of the weekend.
Short Term (through tomorrow night):
A low pressure system will approach the region from the southwest tonight. This low will develop in response to the cold front that passed through the region yesterday and that has subsequently stalled out over the eastern seaboard. Creating a height gradient along the gulf coast. (Classic winter storm set up!) Anyways, this low will be intense because not only is it on the eastern side of an upper level trough, it lies east of a large vorticity maximum. Not to mention the fact that they fall in the left exit and right entrance of two 300mb jet streaks that sit to its southwest and northeast respectively. Current model runs have the rain moving into Pennsylvania late tonight with steady rain developing tomorrow morning. The good news is that because the low is going to track on the western side of the Appalachian mountains, the entire state of Pennsylvania will reside in the lows warm sector keeping temperatures in the upper 40's and lower 50's. The bad news with this track is that the precipitation will train along the Appalachian mountains. The central part of the state will be hardest hit with rainfall totals frequently reaching over an inch with locally heavier rainfall possible by Wednesday morning. This is evident by the SREF 15z run.
Long Term (Wednesday through Friday):
Here is where it gets interesting because currently the models have a brief reprieve in the precipitation on Wednesday afternoon before the chance for showers returns Wednesday night and into Thursday as a shortwave vorticity maximum works it's way across the mid-Atlantic region. However, I am very skeptical of this. If you recall when I said that this set up is very similar to a classic winter storm system. Well typically, when the low tracks up the western side of the Appalachian with one of these systems, a secondary low will develop off the Mid-Atlantic coast and pound Northeastern portions of the state. If this occurs, then the NE, SE, NS, regions could see up to an additional inch of rain before this system gets pushed out of the region by the shortwave on Thursday. Currently the models aren't developing this secondary low, but I'd give it about a 30% chance of developing. So, make sure you watch it! The other thing of note is that behind this low, temperatures aloft will be falling below their critical values. This means that higher elevation areas could see a snow shower or two before everything is all said and done. High pressure will take the region back over on Friday creating sunny and cool conditions for the beginning of Thanksgiving Break!
Longer Range (Through early next week):
MREF 500mb height anomalies show a fairly nice ridge build over the north east through Tuesday so Thanksgiving Break should begin quite comfortably :-)
RJ Patrizio
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