10:50 AM (Wednesday) | *Downpours/strong-to-severe thunderstorms on the table for Thursday/Thursday night in the Mid-Atlantic region…hot, humid weather for Sunday/Monday/Tuesday*
Paul Dorian
An upper-level trough to our west on Thursday will combine with two surface frontal systems and a moist air mass to produce some heavy shower activity in the Mid-Atlantic region and possible late day//evening strong-to-severe thunderstorms. Map courtesy NOAA, tropicaltidbits.com
Overview
The combination of an increasingly moist flow of air, two surface frontal systems, and a slow-moving upper-level trough will raise the prospects for downpours in the Mid-Atlantic region on Thursday and Thursday night and also the chance for strong-to-severe thunderstorm activity. The rain may actually come in two different waves – one late tonight/early Thursday associated with a warm frontal system and a second late tomorrow and tomorrow night associated with a cold front. High pressure builds across the eastern states this weekend and a classic summertime “Bermuda high” setup is likely to result in hot, humid and summer-like weather for Sunday, Monday and Tuesday with high temperatures at or above the 90 degree mark in the I-95 corridor.
The rain on Thursday and Thursday night may be concentrated in two waves with one early associated with a warm frontal system and one in the late day/evening time frame associated with a cold front. Maps courtesy NOAA, tropicaltidbits.com
Details
High pressure will remain in control of the weather around here through the remainder of today, but it’ll shift farther offshore and an increasingly moist south-to-southwest flow of air will intensify on its backside. A warm front will push northward along the east coast early Thursday and then a cold front will approach from the northwest on Thursday night. At the same time, a slow-moving (positively-tilted) upper-level trough of low pressure will approach from the west and it’ll play an important role in the threat of downpours for the Mid-Atlantic region and for the potential strong-to-severe thunderstorm activity.
A stretch of hot and humid weather is likely for the Mid-Atlantic region from Sunday through Tuesday of next week as high pressure shifts to the western Atlantic. Map courtesy ECMWF, tropicaltidbits.com
As the warm front pushes northward late tonight and early tomorrow, an initial round of rain is likely to develop along with a thunderstorm threat and some of this rain can be heavy at times in the increasingly humid air mass. The best chance for downpours during this initial band of rain is likely to be from the I-95 corridor eastward to the coastal sections of New Jersey and the Delmarva Peninsula. There is the chance that rain activity will slacken off or even stop completely during the late morning, mid-day and early afternoon hours on Thursday following the passage of the warm frontal system. By later tomorrow, however, the threat for rain will return as a surface cold front edges closer from our northwest and it’ll combine with the upper-level trough to produce strong upward motion in the Mid-Atlantic region. The combination of the upper-level feature, cold front and peak heating of the day will potentially lead to some strong-to-severe thunderstorm activity from late tomorrow into tomorrow night.
On Friday, the upper-level trough will swing across the east coast and the cold front will tend to fall apart as it clears the eastern seaboard. There can be some residual shower activity on Friday, maybe even a lingering thunderstorm, but the heavy rain threat should be much diminished compared to tomorrow and tomorrow night. High pressure ridging will build into the eastern states on Saturday and then shift off the east coast by Sunday. In this classic “Bermuda high” position over the western Atlantic Ocean, very warm and humid air will flow northeastward into the Mid-Atlantic region for the Sunday/Monday/Tuesday time period. As a result, high temperatures early next week in the DC-to-Philly-to-NYC corridor are likely to be at or above the 90 degree mark. In other words, the hot and humid weather coming for Sunday, Monday and Tuesday will be a true taste of summer - and a far cry from the unusual chill of last weekend.
Meteorologist Paul Dorian
Peraton
peratonweather.com
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