Tuesday, June 12, 2012

Breaking Down Today's Rains

A progressively rainy day is on tap for the Delaware Valley later today as a frontal boundary moves through from the west later on. The front has a good bit of moisture to work with, having been fed over the past 24-36 hours by a steady influx off of the Atlantic, had also will be bringing its own energy to the mix. The result will be a rainy...perhaps thundery day later on through the Delaware Valley. Most computer models are in agreement that a portion of the region will pick up an inch of rain, with two inches of rain not out of the question in the heaviest of rainfall totals later on.

The Euro and GFS both paint heavier swaths of rain to the northwest and to our southeast.  The NAM, which is not shown, was a bit more aggressive with heavy rainfall across Maryland and Delaware later on today in an early morning computer model run, sending that rain northeast into the Philly metro, painting the possibility of two inches of rain for the city and points south.  It is an outlier compared to the other computer models but if thunderstorms do develop to our south later on today and push northeast the potential for a heavier rain and thunder event across these areas could be realized.  It just may not be *that* aggressive compared to what the NAM wants to paint out.   Other runs of the NAM are more in line with the GFS and EURO, painting a heavier rainfall swath northwest and southeast of town.

Rainfall may be steadier, if not heavier, this afternoon and evening across the region.  The best timeframe for heavy rainfall appears to be after 2 PM locally.

While no flood watches are out today, localized ponding of water or some minor flooding can't be ruled out in the "usual suspect" streams and roads that are prone to flooding.   The good news with this front is that its faster movement should result in a relatively nice afternoon after a potentially cloudy and drizzly start tomorrow.