Due to rain cooled air from a passing Mesoscale Convective System, think of a large complex of thunderstorms, the warm front has not yet moved through the Philadelphia and New York City metropolitan areas. However, the warm front is on the move and the development of locally dense fog this morning is a signal to the arrival of the hot and humid air mass on the way which could produce the first heat wave of the early Summer season. I should note Summer doesn’t officially begin into June 21.
Scattered showers will move from west to east and slowly lift north over northeastern Pennsylvania, the Hudson Valley, northern New Jersey, and Connecticut this morning. The showers will linger over Connecticut into the afternoon hours but will be widely scattered in nature. Otherwise, locally dense fog throughout the Philadelphia and New York City metropolitan with visibility below 2 miles in some locations will lift after 10 AM with scattered cloud cover expected. Winds will veer from the southeast to southwest at 5 to 10 mph. Temperatures will vary significantly throughout the region depending on when the warm front lifts through your location. Over Long Island, temperatures will struggle in the mid to upper 70’s. In Connecticut, the Hudson River Valley, and northern New Jersey, temperatures will rise into the upper 70’s to lower 80’s. Over the five boroughs of New York City, the New Jersey coast, and northeastern Pennsylvania temperatures will rise into the lower to mid 80’s. Over southeastern Pennsylvania and much of southern and central New Jersey including the immediate western suburbs of New York City, temperatures will reach the mid to upper 80’s. A marked increase in humidity can be expected.
Once the warm front lifts north, the entire Philadelphia and New York City metropolitan areas will be under the influence of a Bermuda High pattern from tonight on through Sunday. A southwesterly wind will be in place at all levels of the atmosphere transporting a hot, humid, tropical air mass from the Gulf Coast right into the region. Locally dense fog will develop each morning and then lift by 10 AM. Scattered clouds will follow with generally dry conditions. However, a rogue shower or thunderstorm will remain a threat each afternoon and evening. Low temperatures will range from the upper 50’s to lower 60’s over the interior and mid to upper 60’s along the coast. High temperatures will range from the mid to upper 80’s over northern Connecticut, upper 80’s to lower 90’s over the rest of the interior, the Philadelphia metropolitan area, and the immediate New York City metropolitan area, and lower to mid 80’s along the coast and Long Island. Should temperatures break 90 degrees for three straight days, the first official heat wave will be recorded.
A strong cold front will follow on Monday with scattered showers and strong to severe thunderstorms. The thunderstorms will be capable of wind gusts over 50 mph, large hail, frequent lightning, and heavy downpours. Temperatures on Monday will be dependent on the timing of the cold front but should range from the lower to mid 60’s for lows and upper 80’s to lower 90’s away from the coast, lower to mid 80’s along the coast for highs.
Canadian high pressure will take hold by Tuesday with clearing skies and lower humidity. Temperatures on Tuesday will range from the mid to upper 50’s for lows and lower to mid 80’s for highs.