Technical Discussion

Synopsis...

A moisture-rich cold front associated with low pressure over Ontario will keep wet, unsettled weather throughout much of PA through tomorrow afternoon. Once the front passes, expect temperatures to plummet. In the western zones, left over precipitation could change over to snow or a rain/snow mix. Minor accumulations are possible, especially in the higher terrain. Upper level energy will bring snow showers to the Laurel Highlands for Thursday and lake effect snows will be possible Friday and Saturday in the NW and NC zones as winds become more northwesterly. Temperatures during the entire period will be about 5-10 degrees below average.

Short Term (Wed- Wed Night)...

Temperatures overnight tonight across PA have been very mild prior to the passing of the cold front.  At midnight, PHL was at 61 degrees. These numbers will stay up until the front passes. Winds will also continue to be rather breezy (up to 30kts) until the FROPA. Once the front does so, winds should decrease to about 10 kts. Used the WRF for winds since it usually does well. Front is expected to pass around 6z in western PA, 12z in central PA and 18z in eastern PA with model consensus between the WRF and GFS. Rain will be heavy at times through the morning lasting a few hours longer after the FROPA. QPF totals will generally range from 1"-2" with locally heaver amounts.  In the western zones, left over precipitation could change over to snow or a rain/snow mix with minor accumulations possible. After the front passes, expect temperatures to drop throughout the day into the low 30s in the west and mid 30s in the east. Winds will shift and blow from the WSW keeping lake effect snows in NY.

Long Term (Thursday-Sunday)...
*Written by DePodwin, edited by Del Rosso

Typical northwest flow regime sets up for Thurs-Fri with better chances of lake effect of snow on Friday in the NW and NC zones as winds go more northwesterly rather than WSW.  Temperatures in the 30s will be 5-10 degrees below average.  Less chance of snow for Saturday and Sunday but the next shortwave is not far away and could bring a swath of light snow for Sunday night, especially in the western zones.  Next week promises to be active with the possibility of the first major storm of the season.

Adam Del Rosso