Sunday, July 08, 2012

Last Of Remarkable Heat Wave Today

Today is the last of the 90's for a while -- we think...or is that hope.  While we get tantalizingly close to that mark on a couple of occasions this week, we should avoid more than a nuisance flirtation with the 90 degree mark between now and week's end.   Highs reached 90 in a number of locations throughout the region -- including Pottstown, Quakertown, and Blue Bell today -- but lower humidity levels made that heat a good bit more tolerable and at worst, the apparent temperature was around 95 this afternoon at peak heat from the city on north, and in the middle to upper 90's south of the city and over 100 around Washington, DC, which set another record high today.  It's an improvement on 105+ and we're still a day away from breaking the heat wave completely but today should do it for 90's.

We can all celebrate the demise of a nasty, lengthy heat wave that ends up tied for the 7th longest in duration and has sole possession of 6th place on our "Heat Wave Index" for worst heat wave in Philly's modern record.   We've had longer heat waves (12 day heat waves in 1952 and 1999) that were not as intense in terms of temperature but because of six days of 95 or hotter during this last heat wave, plus several nights with high overnight lows, this heat wave does rank more oppressive under our criteria.  Our scoring method gives this a ranking of at least 190 (if you haven't read up with our calculations, here's the primer on it) but depending on the daily low temperature through the end of the day today it could score a little higher.  Regardless, it ranks 6th.  The worst 11 day heat wave was back in 1993...the infamous one that I've talked about several times because it lead to the study on heat that redid all of our heat warnings locally.

For comparison's sake, the worst heat wave last year (July 2011 with the back-to-back 100 degree days) scored 153 over eight days and is one of the top 15 heat waves in this city's history on this scale and is only one of two heat waves to rank in the top 15 through only eight days.  It isn't the first time we have had top 15 heat waves in consecutive years using this scale -- it's been done twice before (1900-1901, 1952-1953).  

Thankfully, it's over...and we should avoid any excessive heat for several days and enjoy a much more tolerable pattern this week.