Mesoscale Precipitation Discussion 0572
NWS Weather Prediction Center College Park MD
1212 AM EDT Wed Aug 01 2018

Areas affected...Virginia Piedmont and Foothills to the DC Metro
Area

Concerning...Heavy rainfall...Flash flooding possible

Valid 010411Z - 011007Z

Summary...Embedded lines of thunderstorms should persist as they
lift north across the VA Piedmont to the DC metro area overnight.

Discussion...Southern Mid-Atlantic radars and GOES-16 imagery
reveals locally heavy scattered showers with a developing line of
heavy thunderstorms with rain rates of 2in/hr extending N-S over
the southern VA Piedmont. A curl in reflectivity on the southern
part of the line suggests an MCV which could aide development
through the overnight hours.

CAMs have not initialized well with this activity, but the latest
HRRR runs suggest heavy elements persisting to the DC metro as the
thunderstorms ride deep layer mean flow out of the SSW at 25kt.
MLCAPE of 500-1000J/kg should maintain convective growth as seen
in recent GOES-16 IR imagery. Moisture is very high across this
area with PW of 2.1in (two standard deviations above the mean) per
02Z GPS data. 1hr FFG is rather high over southern VA, around
2in/hr, but drops to around 1in/hr over the DC metro. The heaviest
rain associated with the MCV looks to track east of the earlier
rainfall over the central VA foothills, but could still cause
additional flooding concerns around KCHO. A track just east of
earlier activity would also reach the DC metro.

Jackson

ATTN...WFO...AKQ...LWX...RNK...

ATTN...RFC...MARFC...SERFC...

LAT...LON   39347768 39247692 38957684 37857741 37377785
            36967851 37277903 37887898 38637829