Thursday Evening Technical Discussion

Synopsis

As an upper level trough approaches from the west, it will replace the 500mb cutoff low that has moved off to the northeast today. Behind this low, there will be strong cold air advection on Friday through Sunday. After the trough departs, a ridge of high pressure will build into the area and promote sunny skies. This should make the pattern feel much more fall-like.

Short Term

Temperatures have begun falling this evening and should continue to fall with lows tonight in most areas in the low-mid 50's. On Friday, skies will be partly cloudy along gusty winds. High temperatures look to reach around 70 in eastern areas while north and west areas will struggle to highs only in the 50's. However, eastern areas will cool off later Friday afternoon as the strong cold front associated with the upper level trough over the great lakes moves through the area. Once this cold front passes through the area Friday afternoon, strong cold air advection will occur. This air will be the coldest of the fall season so far with some locations falling into the mid to low 30's in northwest areas overnight Friday.  The winds will also be strong and will make it feel much cooler. The 21z SREF mean has wind speeds of 15-20 mph with higher gusts over most of the commonwealth. There is also the chance for showers on Saturday as the 500 mb low associated with the upper level strengthens as it moves off to the northeast.

Long Term

Sunday will be brisk as the northwesterly flow over the area continues to dominate. There is the chance on Sunday for more showers as the low pressure system to the east strengthens and creates precipitation over the area.  The 21z SREF mean has an average of .5-1 inches with a maximum in northern PA of near 2 inches. However, once this low departs the area to the northeast, a ridge of high pressure will build in for the start of the week.  Temperatures should rebound in the upper 60's to lower 70's as a result. This air mass will feel much more seasonable and should remain through Wednesday.

-Matt Mehallow