Popping Some PM Storms Wednesday

We have a couple of more days of 90 degree heat ahead before we take a brief break for a couple of days at week's end thanks to a cool front that crosses the region with little bite and some thundery bark to it on Thursday afternoon. Tomorrow is shaping up as the hottest day of the wave with low and mid 90's likely across the region, reaching 94 in Philadelphia if our projections are right.    Along with the heat comes the risk of a pop up thunderstorm in the afternoon hours from the combination of daytime heating and increasing low level moisture.

Computer modeling from the main models like the GFS and NAM, along with higher resolution guidance as seen above suggest the risk of a few pop up thunderstorms tomorrow afternoon and evening across the region.   In addition to the areas outlined above (Eastern PA, New Jersey) on the higher resolution model, the potential also exists in Delaware and in Maryland thanks to the presence of the sea breeze.   We're not looking at anything major in the forecast for the afternoon...just typical summertime heat and typical summertime thunderstorms in spots.   The strongest of storms could bring locally heavy rainfall for some as well.

Memorial Day Warmth Forthcoming

It's going to be a summery Memorial Day weekend, very similar in many respects to last year's weekend when we saw our first 90 degree day of many in 2010.   A summery pattern is generally kicking in starting tomorrow, which offers the outside chance of a 90 degree day in Philadelphia as southerly winds nudge northward and we stay on the warm side of a frontal boundary.   That front fizzles upon crossing the region on Friday night and Saturday, leaving a lingering boundary around on Saturday that could spark a thunderstorm.

The boundary essentially falls apart due to a strengthening upper level ridge of high pressure in the South, which will flex its heat muscle and push warmth up the East Coast.  The ridge weakens slightly on Friday and allows the surface front to push through and brings us scattered thunder chances in the afternoon, with only an outside chance for thunder on Saturday afternoon as the boundary fizzles away.

We could see a thunderstorm any afternoon over Memorial Day weekend but temperatures will be warm -- mid 80's on Saturday and Sunday afternoon, low 90's on Monday as the ridge strengthens further and high pressure entrenches at the surface off the Carolina coastline -- providing an optimal path for heat and humidity.   The Shore will be cooler but still summery -- 70's for highs each afternoon east of the Parkway, 80's west of it.   There could be a seabreeze that pushes further inland each afternoon but by and large it should be a nice weekend.   Again, each afternoon or evening could present an outside chance for thunder but much of the holiday weekend will be awesome.