What was a potential heat wave is now down the toilet for the forecast area, as once again the core of the heat remains to the west thanks to a continued negative NAO pattern.
Saturday and Sunday will be the warmest days as a ridge tries to control our weather before a cold front comes through Sunday afternoon and spoils the fun for heat lovers. Winds will briefly change SW and so highs on Saturday and Sunday will range from the low 80s along the coast to mid to upper 80s for the rest. Sunday some areas around Philadelphia may touch 90 before the cold front comes crashing through
Basically what was possible at first was an area of high pressure and a big ridge building in from the west leading to a potential heat wave, I was never really excited about it given the fact that the real and sustained heat has avoided our area so far this season. Now thanks to a developing upper level low to the east of Maine, the heat will remain away from the area. The circulation around that low will form what we call a “back door cold front” which is a cold front that comes from the East and NE instead of the west due to an upper level low forcing the trough back west. This leads to an easterly wind and so more of a Marine influence off of the Atlantic (still in the mid 50s to mid 60s) and so the core of te heat gets driven west
Above is the general set up for this upcoming week. Sunday late afternoon the cold front will approach from the NE with potential scattered showers and storms and a wind shift to the east, which will drive in a much cooler marine air mass for the start of the new work week, while the heat will be cranking over much of PA into the DC area back into the Midwest with a legit heat wave ( 3 consecutive days at or above 90) for many.
We will have to watch and see exactly where this front sets up and eventually stalls running into the central US ridge but this is the general idea. If your west of the front you can expect a hot start to the week and if your east of the front yu can expect average to slightly below average temperatures for much of next week.
For the forecast area, everyone will be under the influence of the backdoor front so Monday through Wednesday will feature partly sunny skies with temperatures around average to slightly below with highs in the low to mid 70s along the coast and upper 70s to around 80 interior, so still not too shabby as the ridge to the west ill drive in warm air aloft .
Wednesday a cold front will come from the west which will kick out the heat and the marine influence but lead to unsettled weather
This cold front will move east but potentially run into our ridge which is now off the coast, leading the front being very slow-moving and maybe even stall along the coast , which could lead to a wet end to the week, just something to keep an eye on
Behind this front another trough builds down as a ridge develops in the west leading to another potential stretch of below normal temperatures by next weekend.
Here is the summer pattern folks, dominant ridging remains west of us, an on and off negative NAO block with on and off troughs with ridges and heat trying to make a run at us when the NAO block dissipates , another trough comes in from the west , kicks out the heat leading to ridging in the west wash, rinse and repeat. Or basically a bit of a sea saw ride, back and forth with occasional thunderstorm chances