410
AWUS01 KWNH 112245
FFGMPD
NJZ000-PAZ000-DEZ000-MDZ000-VAZ000-DCZ000-WVZ000-OHZ000-120430-
MESOSCALE PRECIPITATION DISCUSSION 1482
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
643 PM EDT SUN OCT 11 2026
AREAS AFFECTED...OHIO VALLEY...CENTRAL APPALACHIANS...MID-ATLANTIC
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 112245Z - 120430Z
SUMMARY...A STRENGTHENING AREA OF LOW PRESSURE IN CENTRAL VIRGINIA
IS LIKELY TO PRODUCE A PIVOTING AXIS OF HEAVY SHOWERS AND
THUNDERSTORMS OVER SOILS THAT RECEIVED 1.5-3" OF RAINFALL TODAY.
WITH RAINFALL RATES BETWEEN 1-2"/HR POSSIBLE, AND MORE URBAN
COMMUNITIES CONTAINING MORE HYDROPHOBIC SURFACES AT-RISK, FLASH
FLOODING WILL BE POSSIBLE THIS EVENING.
DISCUSSION...21Z SURFACE ANALYSIS SHOWS A SURFACE LOW OVER
SOUTHERN WV WEAKENING AT THE SAME TIME SURFACE PRESSURES ARE
LOWERING IN THE MID-ATLANTIC. THE 850MB LOW OVER CENTRAL WV
CONTINUES ITS SLOW PROGRESSION EAST WITH WITH ELEVATED MOISTURE
AND THETA-E LEVELS STARTING TO DECREASE AS THE BEST LIFT AND
MOISTURE MOVES EAST OF THE APPALACHIANS. STILL, ITS SLOW
PROGRESSION IS RESULTING IN STORM STORMS PRODUCING LOCALIZED
RAINFALL RATES OF 1"/HR OVER THE FLASHY PORTIONS OF WESTERN WV.
FARTHER EAST, A WARM FRONT IS SLOWLY LIFTING NORTH AND WEST OVER
THE DELMARVA, BUT IS UNLIKELY TO MAKE IT WEST OF THE I-95 CORRIDOR
BETWEEN DC AND BALTIMORE.
OVER THE NEXT FEW HOURS, AS THE SURFACE LOW STRENGTHENS IN CENTRAL
VA, THE SURFACE-925MB FLOW WILL INTERSECT THE WARM FRONT AND ITS
VAPOR TRANSPORT WILL REVOLVE AROUND THE 925MB LOW'S NORTHERN AND
WESTERN FLANK. THIS SETUP NOT ONLY LEADS TO SOME ADDITIONAL
UPSLOPE ENHANCEMENT INTO THE CENTRAL APPALACHIANS (PARTICUARLY THE
BLUE RIDGE), BUT ALSO CAUSES SURFACE-925MB FGEN OVER THE I-95
CORRIDOR. 21Z RAP SHOWS >1.5" PWS PIVOTING OVER NORTHERN VA,
NORTHEAST MD, AND INTO THE DELAWARE VALLEY AT THE SAME TIME THAT
AS MUCH AS 500 J/KG OF MUCAPE BECOMES AVAILABLE. MOST RAP MODEL
SOUNDINGS ON THE 21Z HRRR SHOW WARM CLOUD LAYERS BETWEEN
10,000-12,000FT DEEP, AND LOW-MID LEVEL RH VALUES AVERAGING CLOSE
TO 90%.
THE LOW PRESSURE SYSTEM EXIT OFF THE COAST LATER TONIGHT, AND THE
WINDOW FOR SLOWER MOVING STORMS MAY BE A FEW HOURS AT MOST. THAT
SAID, FFGS HAVE DIPPED SUBSTANTIALLY OVER WESTERN AND NORTHERN VA,
CENTRAL MD, AND EVEN AS FAR NORTH AND EAST AS SOUTHEAST PA WITH
SOME 1-HR FFGS UNDER 1". UNIVERSITY OF MARYLAND MESONET SITES SHOW
BETWEEN 2-3" OF RAIN HAVE FALLEN SINCE MIDNIGHT IN CENTRAL MD, AND
WHEN FACTORING IN THESE STORMS OCCURRING NEAR A MORE URBANIZED
CORRIDOR FROM NORTHERN VA TO SOUTHEAST PA, THERE IS SOME CONCERN
THAT 1-2"/HR RAINFALL RATES COULD RESULT IN LOCALIZED FLASH
FLOODING THIS EVENING.
MULLINAX
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...AKQ...CTP...LWX...PBZ...PHI...RLX...RNK...
ATTN...RFC...ALR...RHA...TIR...NWC...
LAT...LON 40187596 40167499 39637503 38517636 37927713
37347821 37417913 37608043 37968165 38328211
38928219 39528179 39267989 39567818 40077676
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