Wednesday, July 24, 2013

Respite Of Heat And Humidity Brings Coolest Night Since June For Many

Sunday's conclusion of an eight day heat wave produced the third consecutive year where Philadelphia notched an eight day heat wave -- the first time in Philadelphia's history (since 1872) where we have notched such an accomplishment.  It's a lengthy, although far from a record setting heat wave...but it does set a precedent in Philadelphia.

The other "streak" of note is our streak of consecutive days where the temperature has resided at or above 70 degrees. We're currently entering our 31st day rollin' in this streak.  Whether or not we stay above 70 through 1 AM (midnight standard time) remains to be seen...more on that in a minute.

The 70's streak is probably the most noteworthy thing that comes out of this summer besides the tropical torrent of thunderstorms in much of June or on the couple of soaking occasions in July...or the 90 degree streak -- having seen Philadelphia go a full month without dropping below 70 is unprecedented and breaking a record that's 137 years in the making. This record-setting streak will, ultimately, end tonight at some point as the draw of lower humidity pulls into the region and sets the stage for a couple of relatively cool nights in the Delaware Valley.  Temperatures north and west of the city have a good chance of dropping below 60 degrees by morning as dew points drop into the 50's north and west of Philadelphia.  This will allow for a cool night across Pennsylvania, Northwest New Jersey...however, with the frontal boundary lurking nearby, the threat of showers looms at the Shore and perhaps even up to the New Jersey Turnpike across the Garden State.

You can see how the NAM has the temperature profile cut off pretty sharply from the coast to Pennsylvania -- the frontal boundary lurks along the coast tonight and a ripple of low pressure may fire along the front and bring some showers to Jersey and Delaware overnight.  It looks like the city and points northwest *should* stay dry...and if skies can clear enough, those 50's would definitely seem plausible.