10:15 AM (Thursday) | ***Threat of heavy downpours/strong storms late tonight/early Friday in the DC-to-Philly-to-NYC corridor***

A vigorous wave will cross the Great Lakes today and destabilize the atmosphere in the I-95 corridor later tonight and early Friday. As a result, the threat of showers and thunderstorms will increase in the wee hours of the morning along the DC-to-Philly-to-NYC corridor and continue into Friday morning. Map courtesy ECMWF, Pivotal Weather

Overview

There is a good chance for scattered showers and thunderstorms this afternoon and early evening in the DC-to-Philly-to-NYC corridor and then the threat exists for more widespread showers and thunderstorms late tonight and early Friday. Any of these showers and thunderstorms can result in heavy downpours and localized flash flooding. A combination of ingredients will come together to destabilize the atmosphere in the Mid-Atlantic region including a vigorous upper-level trough of low pressure, strong jet streak and high available moisture. A frontal system involved in this active weather pattern will push through the area later tomorrow likely setting the stage for back-to-back rain-free days this weekend with quite reasonable temperatures for this time of year.

Another key ingredient to the active weather pattern expected late tonight and early Friday is a strong upper-level jet streak. This jet streak will enhance upward motion in the Mid-Atlantic region in the overnight hours contributing to an increasing chance of heavy downpours and strong storms. Map courtesy ECMWF, Pivotal Weather

Details

While there can be scattered showers and thunderstorms this afternoon and early evening, a threat for more widespread showers and thunderstorms exists for late tonight and early Friday. A combination of ingredients will come together later tonight for the destabilization of the atmosphere and the chance of showers and thunderstorms (and heavy downpours) will increase in the wee hours of the morning and that threat will continue into Friday morning along the DC-to-Philly-to-NYC corridor. The greatest chance for severe thunderstorm activity is likely to be in areas to the north and west of the I-95 corridor; however, all areas to the coast can experience strong thunderstorms.

A line of showers and embedded thunderstorms is likely to reach the western part of the Mid-Atlantic region early tonight and then make its way to the I-95 corridor by late tonight or tomorrow morning. Map courtesy ECMWF, Pivotal Weather

A potent upper-level trough of low pressure will cross the Great Lakes later today at the same time a frontal system begins to advance to the north as a warm front into the Mid-Atlantic region. This upper-level low will have a supporting strong upper-level jet streak and this system will tend to take on more of a “neutral” or “negatively-tilted” trough axis (i.e., oriented from northwest-to-southeast) later tonight into early Friday. In addition, another important ingredient is the high level of moisture that is available for the atmosphere to tap into leading to a threat of heavy downpours. Given the already well-saturated grounds, any heavy rainfall late tonight/early Friday can lead to localized flash flooding conditions.

NOAA’s Storm Prediction Center has placed much of the Mid-Atlantic region in the risk zone for severe weather from later today through tonight. The greatest chance of severe thunderstorm activity will likely be to the north and west of the I-95 corridor; however, strong thunderstorms are possible all the way to the coast. Map courtesy NOAA/SPC

Showers and thunderstorms may linger for awhile along and east of I-95 on Friday and then the frontal system responsible for this activity should finally slide through the area by tomorrow night.  Following the passage of the front, drier air should result in back-to-back rain-free days this weekend in the Mid-Atlantic region. Temperatures will be in the moderately warm zone on both Saturday and Sunday with afternoon highs generally confined to the 80’s.

Meteorologist Paul Dorian
Arcfield
arcfieldweather.com

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