An exiting cold front over the DelMarVa became diffuse over southern Maryland and Central VA. Showers and thunderstorms formed and were mainly east of the Blue Ridge.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS LWX wrote it up.
An exiting cold front over the DelMarVa became diffuse over southern Maryland and Central VA. Showers and thunderstorms formed and were mainly east of the Blue Ridge. Isolated severe was possible with damaging winds and heavy rain.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Baltimore/Washington wrote its last area forecast discussion before the first event at Aug 15, 3:10 AM EST, 3 hours 50 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 410 AM EDT WED AUG 15 2012 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION TODAY. HIGH PRESSURE BUILDS INTO THE REGION THROUGH THURSDAY. A SECOND COLD FRONT WILL IMPACT THE MID-ATLANTIC REGION ON FRIDAY AND WILL STALL OVER THE WEEKEND IN SOUTHERN VIRGINIA. && .NEAR TERM /THROUGH TONIGHT/... 07Z SFC ANALYSIS SHOWS REMNANTS OF THE PRIMARY COLD FRONT OVER WRN PA AND CENTRAL WV WHILE A PRE-FRONTAL SFC TROUGH RESIDES FROM SRN NJ SWWD TOWARD SRN MD. ALOFT...A POTENT SHORTWAVE TROUGH OVER WRN KY WILL MOVE EWD...CROSSING THE CENTRAL APPALACHIANS THIS MRNG AND MID-ATLANTIC STATES THIS AFTN. EXPECT THE PRIMARY COLD FRONT BOUNDARY TO JUMP TO THE SFC TROUGH THIS MRNG AS THE UPPER SHORTWAVE TROUGH APPROACHES. THE SFC TROUGH/COLD FRONT WILL NOT ADVANCE EWD MUCH TDA AS SLY FLOW ALOFT PARALLELS THE BOUNDARY. SOME BREAKS IN THE CLOUDS ARE EXPECTED THIS MRNG PRIOR TO THE ARRIVAL OF THE UPPER TROUGH...ESPECIALLY EAST OF THE BLUE RIDGE. FAVORABLE UPPER DYNAMICS AHEAD OF THE TROUGH AND ASSOCIATED ULVL JET STREAK THAT IS ROUNDING THE BASE OF THE TROUGH WILL PROMOTE DEVELOPMENT OF SHOWERS AND STORMS THIS AFTN ONCE THE BOUNDARY LAYER DESTABILIZES SUFFICIENTLY. THE BEST INSTABILITY THIS AFTN IS EXPECTED TO RESIDE NEAR THE FRONT AS A MOIST LLVL AIRMASS LINGERS CLOSE TO THE CHSPK BAY. THERE IS A POTENTIAL FOR SEVERE STORMS /DAMAGING WINDS AND LARGE HAIL/ THIS AFTN ALONG AND EAST OF I-95 WITH MODERATE INSTABILITY...DEEP-LAYER BULK SHEAR INCREASING TO 30-35 KT AND THE AFOREMENTIONED LIFT. FARTHER WEST...DRIER SFC AIR AND MORE CLOUD COVER WILL LIMIT STRENGTH OF CONVECTION. UPPER SHORTWAVE TROUGH AND COLD FRONT EXIT THE REGION BY THIS EVE. CONVECTIVE CHANCES WILL QUICKLY END BY SUNSET AS NW FLOW BEHIND THE FRONT ADVECTS DRIER AIR INTO THE REGION. HIPRES BUILDS IN FROM THE WEST TNGT. CLEARING SKIES AND LGT WINDS WILL PROVIDE DECENT RADIATIONAL COOLING CONDITIONS OVNGT. MIN TEMPS WILL RANGE FROM THE UPPER 50S IN THE WRN HIGHLANDS TO NEAR 70F IN THE CITIES AND ALONG THE COAST. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... UPR RDG AND ATTENDANT SFC HIPRES WILL BE DOMINANT FEATURES THU-THU NGT IN THE MID-ATLC RGN. SLGT DRYING OF LOW LVLS AND SUBSIDENCE WILL YIELD MOSTLY CLR CONDS FOR MUCH OF THU...WITH ONLY A MODEST TERRAIN-FOCUSED CU FIELD. A STRONG CLOSED H5 LOW OVER S-CNTRL CANADA WILL ACQUIRE NEGATIVE TILT AS IT MOVES SLOWLY EWD THU NGT. SWLY LOW-LVL FETCH AHD OF ITS ASSOCIATED CDFNT WILL AID IN MSTR TRANSPORT INTO THE MID-ATLC RGN. THICK CI XPCD TO APRCH THE FCST AREA ON THU NGT FROM THE NW...WITH PCPN XPCD TO APRCH THE WRN ZONES BY FRI MRNG. THERE IS A PSBLTY OF SVR TSTMS FRI AFTN ALONG AND AHD OF THE CDFNT...BUT THERE ARE SVRL PSBL FAILURE MECHANISMS. INCRG CLD CVR AND LMTD MSTR RETURN MAY YIELD ONLY MODEST DESTABILIZATION IN A LRG PORTION OF THE RGN. A LONGER PD OF HEATING IS FCSTD E OF BLUE RDG...WHICH MAY CONTRIBUTE TO GREATER INSTBY AND CONSEQUENT TSTM INTENSITY. CDFNT CROSSES THE RGN FRI EVE. NLY WINDS IN WAKE OF CDFNT WILL SCOUR OUT LOW-LVL MSTR...BUT CLD CVR MAY LINGER INTO SAT MRNG. && .LONG TERM /SATURDAY THROUGH TUESDAY/... HIGHLY-AMPLIFIED UPR AIR PATTERN XPCD THIS WKEND...WITH DP TROF OVER ERN HALF OF CONUS AND STRONG RDG OVER WRN CONUS. FRI CDFNT WILL STALL IN SRN VA ON SAT BFR MOVG SLGTLY NWD IN RESPONSE TO SHRTWV TROF THAT WILL APRCH ON SUN. THE STALLED BNDRY WILL BE THE FOCUS FOR SHWRS AND TSTMS ON SAT. WSWLY STEERING FLOW MAY DIRECT A FEW OF THESE TSTMS INTO SRN PORTIONS OF THE FCST AREA...SO POPS WERE FOCUSED IN SRN ZONES. CHCS FOR PCPN DECR CONSIDERABLY WITH NWD EXTENT. SHRTWV TROF WILL APRCH ON SUN...INDUCING ELY LOW-LVL FLOW N OF THE STALLED FRONTAL BNDRY. THIS MAY ENABLE THE BNDRY TO MOVE SLGTLY NWD ON SUN. THE PRESENCE OF THE BNDRY AND UPSLP ELY LOW-LVL FLOW MAY AID IN GENERATION OF TERRAIN-FOCUSED SHWRS AND TSTMS SUN-SUN NGT. COMPARABLY COOLER AMS WILL ENGULF THE FCST AREA ON SAT AND WILL LINGER THRU EARLY NEXT WK. DAILY MAXIMA WILL BE IN THE UPR 70S-LWR 80S. ONSHORE FLOW XPCD TUE-WED WILL PRESERVE A MOIST BNDRY LYR IN MUCH OF FCST AREA. VERY WEAK MID-LVL FLOW BUT THE PRESENCE OF A WEAK UPR WAVE MAY SUPPORT LOW CHCS FOR SHWRS LATE IN THE FCST PD AS TEMPS RECOVER SLOWLY. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... OVNGT FOG HAS ALREADY LED TO A REDUCTION OF VSBY TO MVFR LVLS AT MRB/CHO....WHERE IT RAINED YDA EVE AND SOME BREAKS IN THE CLOUDS HAVE OCCURRED. IFR CONDITIONS POSSIBLE IN FOG AND/OR LOW STRATUS ERY THIS MRNG AT MRB/CHO. MID-LVL CLOUDS MOVING FROM THE WEST SHOULD PREVENT DENSE FOG FROM FORMING. COLD FRONT/SFC TROUGH HAS PUSHED THRU THE TERMINALS...YIELDING A LGT NWLY FLOW TDA. GENERALLY VFR CONDITIONS AFTER SUNRISE. HOWEVER...SCT SHRA/TSRA EXPECTED TO DEVELOP THIS AFTN AHEAD OF AN UPPER DISTURBANCE. LOCAL/BRIEF RESTRICTIONS POSSIBLE IN STORMS. ACTIVITY SHOULD BE EAST OF BWI/MTN/DCA BY THE EVE AS THE COLD FRONT MOVES OFF THE COAST. DRIER AIR BEHIND THE FRONT SHOULD PREVENT ANY DEVELOPMENT OF FOG. VFR CONDS XPCD THU-THU NGT. CDFNT WILL APRCH FROM THE NW ON FRI AND WILL PROVIDE A FOCUS FOR SHWRS AND TSTMS FRI AFTN AT ALL TERMINALS. CDFNT WILL STALL IN SRN VA ON SAT. BEST CHC FOR CNVCTN DURG THE WKEND WILL BE AT KCHO...WHOSE PROXIMITY TO THE BNDRY MAY ENABLE TSTMS TO IMPACT THE TERMINAL. && .MARINE... AS OF 08Z...SFC COLD FRONT BETWEEN COBB POINT AND LEWISETTA IN THE LOWER TIDAL POTOMAC AND JUST SOUTH OF COVE POINT IN THE MD CHSPK BAY. LGT SLY FLOW RESIDES SOUTH OF THE FRONT AND NWLY FLOW TO THE NORTH. WINDS WILL REMAIN BELOW SCA LVLS TDA. MAIN CONCERN OVER THE WATERS TDA IS POTENTIALLY STRONG STORMS THIS AFTN. SMWS MAY BE NEEDED FOR GUSTY WINDS AND LARGE HAIL. NO SGFNT HAZARDS ANTICIPATED UNTIL FRI...WHEN CDFNT WILL CROSS THE RGN. TSTMS ALONG THIS BNDRY WILL IMPACT THE WATERS FRI AFTN-EVE AND MAY WARRANT SPCL MARINE WRNGS. NLY WINDS XPCD ON SAT BFR AN UPR WAVE APRCHS FROM THE W. THE APRCH OF THIS WAVE WILL YIELD ONSHORE ELY FLOW ACRS THE WATERS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && KLEIN/KRAMAR
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 528 AM EDT WED AUG 15 2012 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 161000- CHESAPEAKE BAY NORTH OF POOLES ISLAND MD- CHESAPEAKE BAY FROM POOLES ISLAND TO SANDY POINT MD- CHESAPEAKE BAY FROM SANDY POINT TO NORTH BEACH MD- CHESAPEAKE BAY FROM NORTH BEACH TO DRUM POINT MD- CHESAPEAKE BAY FROM DRUM POINT MD TO SMITH POINT VA- TIDAL POTOMAC FROM KEY BRIDGE TO INDIAN HEAD MD- TIDAL POTOMAC FROM INDIAN HEAD TO COBB ISLAND MD- TIDAL POTOMAC FROM COBB ISLAND MD TO SMITH POINT VA- PATAPSCO RIVER INCLUDING BALTIMORE HARBOR- CHESTER RIVER TO QUEENSTOWN MD-EASTERN BAY- CHOPTANK RIVER TO CAMBRIDGE MD AND THE LITTLE CHOPTANK RIVER- PATUXENT RIVER TO BROOMES ISLAND MD- TANGIER SOUND AND THE INLAND WATERS SURROUNDING BLOODSWORTH ISLAND-DISTRICT OF COLUMBIA-NORTHERN BALTIMORE-HARFORD- SOUTHERN BALTIMORE-PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS- CALVERT-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX- ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA- KING GEORGE- 528 AM EDT WED AUG 15 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE MARYLAND PORTION OF THE CHESAPEAKE BAY...TIDAL POTOMAC RIVER...AND ADJACENT COUNTIES IN CENTRAL MARYLAND AND NORTHERN VIRGINIA AS WELL AS THE DISTRICT OF COLUMBIA. .DAY ONE...TODAY AND TONIGHT THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TODAY FOR THE OUTLOOK AREA. SOME THUNDERSTORMS THIS AFTERNOON WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND LARGE HAIL. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THUNDERSTORMS ARE EXPECTED ON FRIDAY AFTERNOON AS A COLD FRONT CROSSES THE REGION. SOME STORMS COULD BECOME SEVERE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND AGAIN FRIDAY AFTERNOON AND EVENING. MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504- WVZ050>053-055-501>506-161000- WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD- EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-AUGUSTA- ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE-NELSON- ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-LOUDOUN-ORANGE-CULPEPER- NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND- EASTERN HIGHLAND-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-HARDY- WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL- WESTERN PENDLETON-EASTERN PENDLETON- 528 AM EDT WED AUG 15 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR EASTERN WEST VIRGINIA... NORTHERN AND CENTRAL VIRGINIA...AND CENTRAL AND WESTERN MARYLAND WITH THE EXCEPTION OF GARRETT COUNTY. .DAY ONE...TODAY AND TONIGHT THUNDERSTORMS WILL DEVELOP ALONG A COLD FRONT THAT WILL CROSS THE REGION TODAY. A FEW STORMS EAST OF THE BLUE RIDGE MOUNTAINS COULD BECOME SEVERE AND WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS AND LARGE HAIL. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THUNDERSTORMS ARE EXPECTED ON FRIDAY AFTERNOON AS A COLD FRONT CROSSES THE REGION. SOME STORMS COULD BECOME SEVERE. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND AGAIN FRIDAY AFTERNOON AND EVENING.
The Sterling radar (KLWX), 133 km away, was scanning. The volume nearest the first event began at 11:59 UTC.
1 flash flood. Local standard time, as filed.
There was a road closed due to high water.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2012Every state in 2012This day in weather historyWarnings in Virginia, August 2012
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 409486.