1:00 PM (Monday) - ****It’s déjà vu all over again...strong storms and flooding downpours on the table for the DC-to-Philly-to-New York City corridor****
Paul Dorian
Numerous showers and thunderstorms are likely by later today and early tonight in the Mid-Atlantic region with tropical downpours on the table and there can be isolated damaging winds. Map courtesy NOAA, tropicaltidbits.com
Overview
The combination of a tropical air mass, a slow-moving surface cold front, and an upper-level disturbance raises the chance for afternoon and evening showers and thunderstorms in the Mid-Atlantic region. And, as has been the case quite often in recent days, some of the storms can be strong-to-severe and flooding downpours are on the table with a few inches possible in some spots in a short period of time. While flash-flooding is the greatest concern in this scenario, isolated damaging wind gusts are also possible later today associated with “downburst-type” thunderstorm activity. Looking ahead, while the threat of showers and thunderstorms may diminish on Tuesday, it is likely to rise again at mid-week as a stalled-out frontal system makes a turnaround and heads back to the north as a warm front.
All it takes is a “short-wave” in the upper part of the atmosphere to set off the development of showers and thunderstorms in this tropical environment and that is what we are dealing with today in the Mid-Atlantic region (circled region). Torrential rainfall is on the table all along the Mid-Atlantic’s I-95 corridor from DC-to-Philly-to-NYC. Map courtesy NOAA, tropicaltidbits.com
Details
The atmosphere is destabilizing this afternoon daytime heating approaches its peak for the day and an upper-level shortwave edges eastward towards the Mid-Atlantic region. Showers and thunderstorms are now popping in parts of the area, and the intensity and coverage should increase markedly during the next few hours. Thunderstorms that form in this tropical environment will tend to be slow-movers and capable of producing more than 2 inches of rain per hour with localized amounts of 3-6 inches possible anywhere along the DC-to-Philly-to-NYC corridor. Any rain that falls will come on well-saturated grounds raising the serious concern for flash-flooding conditions which has been a rather persistent problem in recent weeks.
The risk is high in the Mid-Atlantic’s I-95 corridor for excessive rainfall later today and tonight which can cause localized flash-flooding conditions in the DC-to-Philly-to-NYC corridor. Map courtesy NOAA/SPC
In terms of winds, while widespread damage is not likely, however, there certainly can be some “downdraft-related” high wind gusts potentially producing damage in isolated spots later today and early tonight. Looking ahead, while the threat of showers and thunderstorms may diminish in much of the Mid-Atlantic region on Tuesday, an enhancement of the threat of rain is likely to return later Wednesday as a stalled-out frontal system makes a turnaround and heads back north as a warm front. Heat and humidity for the week will likely peak on Thursday following the passage of the warm front with low-to-mid 90’s possible for afternoon highs in the I-95 corridor, and the unsettled weather pattern will continue with a daily shot at showers and thunderstorms.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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