Monday Mid-Day Update - ***Tropical moisture enhances the threat of flooding downpours in the Mid-Atlantic region...daily threat of showers and storms likely to last right to the weekend***
Paul Dorian
“Precipitable water” amounts are high today along much of the Atlantic seaboard with tropical moisture firmly in place. As a result, there can be tropical downpours during the next couple of days in the Mid-Atlantic region with flash-flooding a high concern given the already well saturated grounds in most areas. Map courtesy NOAA/SPC
Overview
A very unsettled stretch of weather is in store for the Mid-Atlantic region with a shot of showers and thunderstorms on a daily basis right into the upcoming weekend. The rainfall during the next few days will be enhanced by a tropical air mass that pushed northward this weekend along with the remnants of Tropical Storm Chantal. In addition, a slow-moving upper-level trough of low pressure now centered over the Great Lakes will enhance upward motion in the Mid-Atlantic region between now and mid-week. As a result, tropical downpours are possible during each of the next few days which can bring flash-flooding conditions to portions of the Mid-Atlantic region with today’s greatest concern centered around the Chesapeake Bay region. Any thunderstorm from later today into the mid-week can reach strong-to-severe levels with perhaps the highest risk of severe weather coming on Tuesday afternoon and evening.
Tropical Storm Chantal formed during the weekend over the western Atlantic and then its remnants pushed northward into the southern Mid-Atlantic region by early today. While the system has weakened, its tropical moisture field will enhance rainfall in the region during the next couple of days. Map courtesy NOAA/NHC
Details
A tropical system that was meandering around the Florida Peninsula during much of last week drifted northeastward this past weekend to a position over the very warm waters of the southwestern Atlantic Ocean. As such, atmospheric conditions became quite favorable for intensification and Tropical Storm Chantal was born just off the Carolina coastline and it then drifted northward into the southern Mid-Atlantic region by early today. Tropical moisture is now fully entrenched in the Mid-Atlantic region, and it is “available for the taking” by the atmosphere once there is some kind of lift or upward motion. Indeed, that lift or upward motion in the atmosphere is already happening because of some daytime heating, and the increasing influence by an upper-level trough now situated over the Great Lakes.
A very unsettled stretch of weather is coming to the Mid-Atlantic region and some spots can receive as much as half a foot of rain with flash-flooding a high concern. Map courtesy NOAA/WPC
Tropical downpours are likely both today and tonight in the Mid-Atlantic region and flash-flooding conditions can develop with the likelihood of this heavy rainfall on top of already well-saturated grounds. The threat of heavy rain will continue Tuesday and Wednesday, and strong-to-severe thunderstorms can enter the picture. In terms of rainfall amounts, a couple of inches is likely in most areas by mid-week and - with the extremely humid air mass in place - there is the potential that some spots receive as much as 4-6 inches of rain with perhaps the highest region of concern being near the Chesapeake Bay (e.g., eastern side of DC metro, Delmarva Peninsula). With the upper-level trough hanging nearby, the Thursday through Sunday time period will be unsettled as well with the threat of daily showers and thunderstorms likely to continue.
As far as temperatures are concerned, clouds and rainfall will be a limiting factor during much of this unsettled stretch resulting in highs generally in the 80’s across the DC-to-Philly-to-NYC. The one exception may be on Tuesday when temperatures could peak in the 90–95-degree range for afternoon highs all along the I-95 corridor making for very uncomfortable conditions as humidity levels will remain quite high and uncomfortable...no intense heat is in sight.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com
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