CWS Technical Discussion

Sunday Night Technical Discussion

Synopsis:

Dangerous flooding is likely throughout much of the central part of PA this week as remnants of tropical storm Lee will stall out over the area thanks to a strong boundary between moist tropical air over eastern parts of the country and very dry air over the Midwest. Western regions of the state will be spared the brunt of the rainfall, with areas of the northwest seeing the least amount of rain. The frontal system will finally move out this coming weekend allowing things to dry out.

 

Short Term:

A steady flow of moisture from the Gulf Coast will continue to stream northeastward for the middle of the week. A boundary between the moist air mass created by ex-tropical storm Lee and dry air over the central plains will stall a front over the east. Both the GFS and the WRF have the heaviest rain falling across central PA on Wednesday morning continuing through the day as the deepest tropical moisture passes over the area. SPC plumes for total liquid precipitation put the Centre region at just over three inches by Wednesday morning, with an additional inch falling throughout the day. Regions to the east and west will see less rainfall depending on how far out you go. All in all, a fairly tight precip gradient is set up and the final track of Lee will be important in determining who will see the most rainfall.

 

Long Term:

Once Lee moves on after Wednesday, things will begin to calm down across the commonwealth. The WRF model is still showing patchy areas of precipitation throughout much of the state, however not nearly as significant as what we can expect for the beginning of the week. Much of the rain will be concentrated around the eastern third of the state, with SPC plumes predicting anywhere from 5-8 inches of rain for the area by the end of the week. Major flooding will continue to be a concern for the already soggy region. Temperatures will begin a slight warming trend as a few breaks in cloud cover from time to time will allow for a little sunlight to get through. The GFS model has a trough building in by the end of the week that should help to kick the stationary front out of the region and finally allow for some drying-out to occur.

-Heather Waldman