787
AWUS01 KWNH 161401
FFGMPD
VAZ000-NCZ000-162000-
MESOSCALE PRECIPITATION DISCUSSION 1091
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1001 AM EDT TUE SEP 16 2025
AREAS AFFECTED...SOUTHEAST VA AND FAR NORTHEAST NC TIDEWATER
REGION
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 161400Z - 162000Z
SUMMARY...ONGOING HEAVY RAINFALL ACROSS PARTS OF SOUTHEAST VA AND
FAR NORTHEAST NC ASSOCIATED WITH A POTENT NEARBY COASTAL LOW IS
EXPECTED TO CONTINUE THROUGH AT LEAST THIS AFTERNOON. MAXIMUM
RAINFALL RATES ARE EXPECTED TO REMAIN IN THE 1-3"/HR RANGE, WITH
6-HR TOTALS UP TO 4". THIS IS ANTICIPATED TO LEAD TO SCATTERED
INSTANCES OF FLASH FLOODING, WHICH MAY BE EXACERBATED DUE TO
COASTAL FLOODING IMPACTS AND URBANIZED GROUND CONDITIONS.
DISCUSSION...LATEST GOES-EAST VISIBLE SATELLITE IMAGERY HIGHLIGHTS
A COMPACT SURFACE LOW PRESSURE SYSTEM ABOUT 40 MILES EAST OF THE
NC OUTER BANKS, WITH REGIONAL RADAR IMAGERY AND SURFACE
OBSERVATIONS DEPICTING MODERATE TO LOCALLY HEAVY RAINFALL ACROSS
COASTAL SECTIONS OF VA AND FAR NORTHEAST NC. RAINFALL AMOUNTS
THROUGH 1330Z OF 1.5-2.0" HAVE BEEN REPORTED IN THE
NORFOLK/VIRGINIA BEACH REGION, MAINLY ASSOCIATED WITH A BAND OF
HEAVY RAINFALL THAT MOVED WESTWARD THROUGH THE REGION THIS
MORNING. THE HIGHEST RAINFALL RATES (UP TO 3"/HR PER MRMS) ARE
CURRENTLY OFFSHORE AND ASSOCIATED WITH THE DEEPEST CONVECTION
(COLDEST CLOUD TOPS AROUND -66C) NEAR THE LOW PRESSURE CENTER.
HOWEVER, AN AXIS OF LOW-LEVEL CONVERGENCE EXTENDS TO THE NORTHWEST
ALONG THE VA/NC COASTLINE AND ENHANCED BY 30-40KT
EAST-NORTHEASTERLY 850MB WINDS AND AN ASSOCIATED WARM FRONT
EXTENDING EAST-NORTHEAST FROM THE LOW PRESSURE SYSTEM. THIS STRONG
EASTERLY FLOW, WHILE ENHANCING CONVERGENCE, IS ALSO MAYBE MORE
IMPORTANTLY AIDING TO INCREASE MUCAPE ABOVE 500 J/KG PER THE
LATEST RAP INTO NORTHEAST NC. ELEVATED INSTABILITY IS EXPECTED TO
CONTINUE INCREASING GRADUALLY THROUGH THIS AFTERNOON AS THE
SURFACE LOW SLOWLY DRIFTS NORTH-NORTHWESTWARD, AS WELL AS PWS
WHICH SHOULD REMAIN NEAR OR SLIGHTLY BELOW 2". THIS WILL HELP
MAINTAIN RAINFALL RATES IN THE 1-3"/HR RANGE AND EVENTUALLY LEAD
TO GREATER COVERAGE OF THESE HIGHER RATES THROUGH AROUND 20Z AS
ADDITIONAL RAINBANDS MOVE INLAND.
RADAR REPRESENTATIONS OVER THE NEXT 6-HRS WILL LIKELY EXHIBIT
NORTH-SOUTH BANDS OF HEAVY RAINFALL MOVING INLAND ALONG THE COAST
WHERE GREATEST CONVERGENCE EXISTS INTERSECTING THE COASTLINE AND
INFLUENCE FROM AN ASSOCIATED WARM FRONT AND EASTERLY FLOW. THESE
BANDS WILL LIKELY WEAKEN AS THEY PROGRESS WESTWARD, BEFORE BEING
REPLACED BY NEW HEAVY RAINFALL BANDS ORIENTED IN A SIMILAR FASHION
AS THE COASTAL LOW DRIFTS CLOSER TO SOUTHEAST VA. LATEST HRRR AND
EXPERIMENTAL RRFS GUIDANCE DEPICTS ADDITIONAL RAINFALL AMOUNTS UP
TO 4" POSSIBLE THROUGH 20Z AND MOST LIKELY ALONG THE IMMEDIATE
COAST OF SOUTHEAST VA AND THE SOUTHERN DELMARVA PENINSULA, BUT
WITH EVEN HEAVIER AMOUNTS POSSIBLE JUST AFTER 20Z. THESE RAINFALL
AMOUNTS WHEN COMBINED WITH COASTAL FLOODING AND ANY URBAN
INFLUENCE (I.E. NORFOLK/VIRGINIA BEACH) ARE LIKELY TO LEAD TO
SCATTERED INSTANCES OF FLASH FLOODING DURING THIS TIME PERIOD.
ADDITIONAL MPDS WILL LIKELY BE NEEDED THIS EVENING AS THE EVENT
CONTINUES THROUGH TONIGHT.
SNELL
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...AKQ...
ATTN...RFC...ALR...RHA...NWC...
LAT...LON 37727599 37647566 37447549 37257559 36887571
36457573 36377601 36707647 37107668 37427662
37647633
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