MESOSCALE PRECIPITATION DISCUSSION 0243
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 PM EDT THU MAY 31 2018
AREAS AFFECTED......EASTERN WV TO NORTHERN VA AND THE DC TO
BALTIMORE METRO...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 311827Z - 010027Z
SUMMARY...HEAVY SHOWERS/STORMS ARE FORECAST TO MOVE EAST ACROSS
EASTERN WV AND MD/NORTHERN AND CENTRAL VA THIS AFTERNOON. PRIOR
RAINS HAVE RESULTED IN AREAS PRONE TO FLASH FLOODING SO PATCHES OF
1-3 INCHES OF RAIN COULD CAUSE FLOODING.
DISCUSSION...REGIONAL RADARS AND SATELLITE HAVE SHOWN AN INCREASE
IN SHOWERS/STORMS ACROSS EASTERN WV AND WESTERN MD EARLY THIS
AFTERNOON. THESE STORMS WILL MOVE ACROSS NORTHERN VA AND CENTRAL
MD INTO THE WASHINGTON DC AND BALTIMORE CORRIDOR EITHER LATE THIS
AFTERNOON OR EARLY EVENING.
DIURNAL DESTABILIZATION AND DEEP MOISTURE WITH IMPRESSIVE MID 70S
DEWPOINTS FURTHER EAST SUPPORT ADDITIONAL SHOWERS/STORMS ...AIDED
BY LIFT CREATED BY UPPER LEVEL DIVERGENCE MAXIMA AND A WARM FRONT
CROSSING NORTHERN VA/MD.
THE MORNING SOUNDING FROM DULLES VA INDICATED SURFACE-500 MB
RELATIVE HUMIDITY OF 90 PERCENT...SO SHOWERS WILL BE EFFICIENT
RAINFALL PRODUCERS.
THESE AREAS HAVE RECEIVED HEAVY RAINS LAST NIGHT OR EARLIER THIS
WEEK SO ARE PRONE TO FLOODING IF ADDITIONAL HEAVY RAINS OCCUR.
SOME FLASH FLASH GUIDANCE IS AS LOW AS HALF AN INCH IN 6 HOURS IN
THE CHARLOTTESVILLE VA AREA WHERE HEAVY RAIN FELL LAST NIGHT.
THERE ARE A COUPLE OF DIFFERENT BANDS WITH THE POSSIBILITY OF MORE
THAN ONE BAND IMPACTING A GIVEN LOCATIONS...WHICH WOULD RESULT IN
LOCALIZED HEAVY RAIN TOTALS.
INFLOW FROM SOUTHERN VA HAS NEAR 1500-2000 J/KG OF MIXED LAYER
CAPE...WITH OUTFLOWS PROVIDING WELL DEFINED BOUNDARY LAYER
MOISTURE CONVERGENCE...SO ADDITIONAL SHOWERS/STORMS ARE EXPECTED.
THE WRF ARW AND ARW 2 AND THE 15-16Z HIGH RES RAPID REFRESH SHOW
SPOTTY 1-2 INCHES OF RAIN WITH MAXIMA TO 3 INCHES WHERE CELL
MERGERS...BRIEF TRAINING OR MORE THAN ONE ROUND OF SHOWERS/STORMS
OCCUR.
PETERSEN
