For the second time in the last three weeks, a large quantity of rainfall is targeting the D.C. metro region – focused Thursday into Friday.
The front crawling through the center of the nation (see below) will draw a deep plume of tropical moisture northward, setting the stage for showers and thunderstorms that may be prolific rain producers.
Writes the National Weather Service forecast office in Sterling:
A STRONG LOW LEVEL JET AHEAD OF THE FRONT WILL EFFECTIVELY USHER MOISTURE INTO THE MID ATLANTIC THROUGH THE DAY THURSDAY. WITH PRECIPITABLE WATER VALUES BETWEEN ONE AND A HALF AND TWO INCHES OVER THE AREA FROM THURSDAY EVENING THROUGH FRIDAY MORNING AND MODERATE INSTABILITY AHEAD OF THE FRONT…PERSISTENT MODERATE TO HEAVY RAINS COULD LEAD TO FLOODING CONCERNS.
We do not expect this to be the kind of long duration heavy rain event that set records to close April, but the rains could be just as intense (if not a little heavier) for a time.
The heaviest rainfall may set up along the spine of the Appalachians, but models suggest the potential for a few inches of rain in the immediate metro region. Officially, the National Weather Service Weather Prediction Center forecasts 2-4 inches of rain in the region.
Timingwise, both the European and GFS models suggest the heaviest rain will fall locally late Thursday night into early Friday morning, but may linger through midday Friday.
I wouldn’t be surprised to see flash flood watch issued in the next couple days.
Jeff Halverson, our severe weather expert, will have more on the late week rain-storm threat tomorrow.