Generous Rains For Some...Others Could Use More

Yesterday's rains and thunderstorms put a dent into our muggies for a couple of days, coming with the price of localized flooding and damage to property and tree, but bringing some decent dents into the rainfall deficit that's been a part of our region for the past couple of months.  Rainfall totals varied a good deal based on location, with localized downpours bringing some folks two inches of rain while bringing others just a half inch 10 minutes down the road.   Philadelphia did pick up 1.48" of rain yesterday but that was hardly a representative total of the whole region as some spots picked up over two inches and others did not fare as well.   Regardless, most everyone saw at least some rain yesterday.  

Yesterday's thunderstorms were brought to you by a disturbance tracking along a stalled frontal boundary.   This weak low enhanced thunderstorms across our region while bringing additional fuel in along its path.   You can see the evolution of those storms in three separate radar screen shots (from wunderground.com) at 12:30, 2:30, and 4:30 PM.

Storms initially popped up and moved little, leading to highway flooding across South Jersey during the early and mid afternoon hours.   Thunderstorm coverage in the early afternoon was initially scattered and slowly spread out to become more widespread as the atmosphere "broke" from the heat cap that had been in place. Whether the expanding thunderstorm coverage looked like abstract art or The Blob (hat tip to the festival in Phoenixville this weekend) is up to the eye of the beholder but thunderstorms increased in coverage through the afternoon.

By 4:30, a bit of a squall line developed across New Jersey back into Delaware, with a secondary line back to the northwest over the Lehigh Valley through Lancaster.  This secondary line joined up with the Jersey line and the larger line of thunderstorms gradually pushed themselves east to the coast over the course of several hours.  

By 7 PM, the line (below) and the band of thunderstorms took up the width of New Jersey, taking another three hours or so to pull off the coast completely due to their relatively slow movement.   While rainfall totals were scattered around through the region, areas to the south and southeast of Philly did pick up more rain on the whole than areas north/west (in some cases more than two inches in parts of the Pinelands).

Yesterday's storms won't take away the warmth -- but they did take away the humidity as dew point values will be closer to 60 today than yesterday's lower and middle 70's.   While it will still be warm (approaching 90), the humidity will be tolerable.

Tonight's Storms Primer

A warm afternoon across the Delaware Valley will give way to a rather warm night -- with temperatures hard pressed to drop below 60 in many locations overnight as increasing clouds and gusty winds from the south help maintain warmth through the Delaware Valley.   Radar is showing a couple of bands of thunderstorms across Pennsylvania -- generally across Northern and Western Pennsylvania -- ahead of the cold front that is still back in Ohio.  Those thunderstorms...and the ones along the front...are moving northeast and it will take much of the night for the storms to reach the Philadelphia region.

Radar simulation from the Storm Prediction Center is suggesting storms should not reach the Philadelphia region until the early morning -- generally after 2 AM in Berks and the Lehigh Valley, after 4 AM in the Philadelphia region.   Thunderstorms will bring gusty winds with them -- perhaps to over 50 mph in the strongest of storms and a few severe warnings can't be ruled out late tonight or early tomorrow morning.

Storms will move through until midday -- ending from west to east.   The warmth that will last through the night will end quickly tomorrow morning with the frontal boundary crossing the region.   Temperatures will drop from the lower 60's to perhaps the middle and upper 40's before temperatures rebound somewhat in the afternoon hours as the sun tries to return.    Our "Spring Fling" will be short lived...and end with a rumbling.

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