A well-needed and well-timed set of changes will kick in from the National Weather Service starting on December 4th for the suburban counties in Southeastern Pennsylvania. Given the uniqueness of suburban Philadelphia geography and how the counties outside of Philadelphia range from low elevation to nearly 1000 foot hills in Bucks and Chester Counties, there is typically some discrepancy in winter when it comes to warnings and advisories when a whole of a suburban county gets warned or thrown into a weather advisory for only its northern and western portion.
That will change somewhat this winter!
Effective December 4th, the NWS will divide Chester, Montgomery, and Bucks Counties into two forecast zones per county from its current one zone per county. This will allow for a better handling of winter storm warnings, flood watches, and other advisories that need to be issued for portions of a county but not the whole of it.
The effective dividing line is roughly along Route 202 in Bucks and Montgomery Counties (a little west of it in Montco), and in Chester County it runs along 202 before diving southwest near Exton and running roughly down the center of the county from that point.
Going forward this winter, we should see fewer advisories and warnings for the whole of the county if advisory or warning impacts are only felt in a portion of it. This should limit warning confusion for some of you in the lower sections of the county.