Wednesday Afternoon Technical Discussion

Overview:
The storm system that brought the icy conditions to Pennsylvania this morning will lift off to the Northwest this evening.  A weak ridge of high pressure will move over the region late tonight and into tomorrow attempting to dry out the state. However, lingering low level moisture will only allow for the sun to occasionally peak out tomorrow before out next system moves into the area. This system will bring a quick burst of light snow across the commonwealth with the western mountainous regions seeing the heaviest accumulation Friday and into Friday night. Behind this system conditions will get very cold as a strong northerly flow will cause the temperatures to struggle to get out of the teens on Saturday.

Short Term:
The system that brought the precipitation to the state today will move out to see tonight allowing for a weak area of high pressure to develop in its wake. However, this high pressure system is more a result of a lull between two storm systems rather than a true winter high. This means that although the models are trying to bring in dry air at the 700mb level for Thursday, low level moisture will keep most of the state cloudy during the day with only partial clearing Thursday evening. The next system will approach the region Thursday night causing clouds to be on the increase towards Friday morning. Temperatures will also be on a downward trend over the next few days.

Long Term:

The snow will move into the state sometime late Thursday night or early Friday morning. All of the critical temperatures are to the south of PA so this will be an all snow event. The WRF model has been fairly consistent about when the snow will move into the state however, the 18z run has a bit less precipitation falling. Therefore, I would tend to be a bit conservative on my snowfall totals, especially in the central mountains of Pennsylvania.  The GFS has had a lot more variability from run to run, however, the 18z run is quite similar to the 18z WRF.

Longer Term:

Behind this system, a stiff northerly flow will cause temperatures to plummet for the beginning of the weekend with temperatures in the single digits Friday and Saturday night and daytime highs struggling to get out of the teens on Saturday.

RJ Patrizio