Dry air and strong wind shear have decimated tropical storm Karen, which is barely hanging on in the northern Gulf of Mexico.  Any meaningful impact from Karen in the D.C. area has evaporated, but a strong cold front is still likely to bring some heavy rain and possible thunderstorms to the D.C. area on Monday.

Water vapor image of Karen shows huge area of dry air (in brown) near its center and west of its thunderstorms. (NOAA)

Karen’s peak winds have weakened to 40 mph, and is a minimal tropical storm.  It’s currently stationary, about 290 miles south-southwest of the mouth of the Mississippi river.  It is expected to resume a track to the north and then northeast, moving over southeast Louisiana early Sunday and then towards coastal Alabama and Mississippi later in the day.  It’s likely to lose more steam along the way and become a depression.

(National Hurricane Center)
(National Hurricane Center)

By Monday, what’s left of Karen will drift across the Southeast and dissipate, avoiding the Mid-Atlantic.  So we will need to rely on an inbound cold front, which should draw up some tropical moisture, for our rain.

This front will be dynamic and on the slow-moving side with the potential to bring a period of heavy rain and possible thunderstorms. Rainfall amounts of 0.5-1.5 inches are possible, with the most likely period for rain between midday and around 10 p.m.

Rainfall forecast through Thursday (National Weather Service)

If there is some sunshine Monday before the rain moves in, there’s a possibility of some strong storms and even an isolated tornado threat given strong low level wind shear ahead of the front.  We’ll have additional updates on the storm potential over the next couple days.