A high pressure system developing off the North Carolina coast this morning will transport the Summer's first hazy, hot, and humid air mass into the Philadelphia and New York City metropolitan areas. Along with the rising temperatures to above normal levels will come the threat for widely scattered showers and strong to severe thunderstorms each afternoon. The hot and humid pattern will break just in time for next weekend but not without a very stormy night on Friday.
Today, as high pressure becomes established off the North Carolina coast, clouds will increase and winds will back to the southwest at 5 to 15 mph. An isolated shower or thunderstorm will be possible this afternoon. Temperatures will rise into the mid 80's over the Philadelphia metropolitan area, lower to mid 80's in the New York City metropolitan area, and mid to upper 70's over Long Island.
As the tropical air mass becomes established over the northern Mid Atlantic tonight, scattered clouds can be expected with areas of fog developing towards morning. The fog will be locally dense leading to visibility falling below 2 miles at times. Low temperatures will fall into the lower to mid 60's.
The hazy, hot, and humid weather pattern will be locked in tomorrow on through Friday. Fog will be a threat each morning, reducing visibility below 2 miles at times. Disturbances diving from the Great Lakes towards the Philadelphia and New York City metropolitan areas will support the threat for widely scattered showers and strong to severe thunderstorms. The strongest thunderstorms will be capable of wind gusts over 50 mph, frequent lightning, hail, very heavy downpours, and even an isolated tornado. Complex of showers and thunderstorms featuring very heavy rainfall, wind gusts over 60 mph, and frequent lightning will be a threat in the late night and early morning hours as well. Low temperatures through the period will range from the mid to upper 60's over the interior and upper 60's to lower 70's along the coast and in urban locations. High temperatures will range from the lower to mid 90's in the Philadelphia metropolitan area, upper 80's to lower 90's in the New York City metropolitan areas, and lower to mid 80's over Long island.
A powerful cold front will move through the region on Friday evening with widespread showers and thunderstorms. High pressure from the Canadian Maritimes will build south on Saturday and Sunday with scattered cloud cover. Low temperatures will range from the upper 50's to lower 60's. High temperatures will range from the upper 70's to lower 80's.