11:40 AM | ***Heavy rain and a strong-to-severe thunderstorm threat in the Mid-Atlantic region from early tonight into early Thursday***
Paul Dorian
A low-level jet streak will develop later tonight over the Mid-Atlantic region and it will play a key role in increasing instability in the atmosphere. Map courtesy Canadian Met Centre, tropicaltidbits.com
Overview
An active weather pattern continues across the nation with multiple upper-level disturbances moving along in a west-to-east fashion and this is resulting in numerous rain threats for the Mid-Atlantic region. One such upper-level disturbance will help set off the formation of a low pressure system today over the Upper Midwest and this system will intensify later tonight over the Mid-Atlantic region enhancing the chance here for some heavy rainfall, flash-flooding, and potentially strong-to-severe thunderstorm activity.
A frontal boundary zone exists at mid-day near the east coast and this will form the region where low pressure intensifies in the overnight hours. Map courtesy NOAA/WPC
Details
A frontal boundary zone along the east coast will act as a focus area later today and tonight for the intensification of low pressure. This developing system is now over the Upper Midwest and will deepen later tonight after moving northeastward towards the Mid-Atlantic coastline. This system will be supported by a vigorous wave of energy in the mid-levels of the atmosphere that will help to produce strong upward motion later tonight in the Mid-Atlantic.
Another key player in the unfolding weather event for the Mid-Atlantic region is a vigorous wave aloft that will enhance upward motion later tonight. Map courtesy NOAA, tropicaltidbits.com
Another key factor in this unfolding scenario will be the formation of a strong low-level jet streak of around 50 knots that will be just a few thousand feet off the surface. This jet streak will act in a couple of ways to increase instability in the atmosphere. First, these winds will advect some high humidity air into the region which increases the chance for heavy rainfall and perhaps sets the stage for localized flash-flooding. Second, wind shear associated with this low-level jet streak will increase the chances for damaging wind gusts in any late night strong-to-severe thunderstorm. The rain later tonight can come through the Mid-Atlantic region in multiple bands and can last all the way into the early morning hours on Thursday with around 0.75 to 1.5 inches likely in most areas, but even higher amounts are possible in spots.
High-resolution forecast map of radar reflectivities as of 4AM, Thursday, June 9th. Map courtesy NOAA, tropicaltidbits.com
The overall weather pattern will calm down some by tomorrow afternoon following clouds early in the day and the possibility of lingering showers and thunderstorms. High pressure takes control later in the day, dry air pushes into the region on NW winds, and a comfortably cool night will follow. The weather remains nice on Friday, but then the weather goes downhill later Friday night. Another low pressure system will develop in the Mid-Atlantic region on Saturday and there will be a noticeably cooler air mass pushing into the area. Showers are likely on Saturday to go along with the unusually cool conditions and temperatures doing no better than the lower 70’s for afternoon highs. It’ll stay unsettled on Sunday given the chilly air aloft with the continuation of below-normal temperatures and the threat of showers.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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