An upper level low moved into the Mid Atlantic and showers and thunderstorms formed as a shortwave trough moved across.
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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 upper level low moved into the Mid Atlantic and showers and thunderstorms formed as a shortwave trough moved across.
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 21, 2:05 PM EST, 2 hours 15 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 305 PM EDT WED AUG 21 2013 .SYNOPSIS... AN UPPER LOW APPROACHES FROM THE MIDWEST THROUGH TONIGHT. THE UPPER LOW WILL PASS THROUGH THE REGION ON THURSDAY. A COLD FRONT WILL MOVE THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY MORNING BEFORE HIGH PRESSURE BUILDS OVERHEAD DURING THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AN UPPER LOW NEAR THE IN-OH BORDER THIS AFTN WILL CONTINUE TO MOVE EWD TNGT TOWARD THE CENTRAL APPALACHIANS. SWLY FLOW AHEAD OF THIS LOW AND AROUND THE BACKSIDE OF THE WRN ATLANTIC HIGH WILL CONTINUE TO DRAW A PLUME OF TROPICAL MOISTURE UP THE ERN SEABOARD. AFTN TEMPS IN THE MU 80S AND DEWPOINTS NEAR 70F HAS RESULTED IN ABOUT 2000 J/KG OF MLCAPE AS ANALYZED ON SPC MESOANALYSIS AND RECENT ACARS SOUNDINGS. UPPER DIVERGENCE/DPVA AHEAD OF THE LOW IN COMBINATION WITH LOCAL CONVERGENCE VIA TERRAIN CIRCULATIONS HAVE PROVIDED THE NECESSARY LIFT FOR SHOWERS AND STORMS TO DEVELOP ALONG THE RIDGES OF THE POTOMAC HIGHLANDS AND BLUE RIDGE. CONVECTION WILL BE SLOW TO ADVANCE EWD WITH WEAK STEERING FLOW. MAJORITY OF THE THIS ACTIVITY THRU SUNSET MAINLY CONFINED TO THE HIGHER TERRAIN... ALTHOUGH A FEW SHOWERS OR STORMS MAY TRY TO MOVE INTO THE WRN SUBURBS OF DC/BALTIMORE LATE IN THE DAY. THE MAIN IMPACT FROM THIS CONVECTION WILL BE LOCALLY HVY RAINFALL...BUT FLASH FLOODING THREAT IS LIMITED WITH DRY ANTECEDENT CONDITIONS. CONVECTION THAT DEVELOPED OVER THE MTS THIS AFTN MAY EVENTUALLY SPREAD EWD INTO THE I-95 CORRIDOR TNGT AS LOW ADVANCES EWD. DESPITE THE LOSS OF DAYTIME HEATING....MODEL SOUNDINGS SHOW VERY MOIST LLVLS WITH ENOUGH ELEVATED INSTABILITY PRESENT FOR AN ISO TSTM EVEN OVNGT. LEANED ON THE WARMER SIDE OF MIN TEMP GUIDANCE WITH CLOUD COVER OVERHEAD AND HIGH DEWPOINTS IN PLACE. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/... UPPER TROUGH WILL MOVE THRU THE MTS THU MRNG. EXPECT SOME SHOWERS TO BE ONGOING IN THE MRNG MAINLY ALONG AND EAST OF THE I-95 CORRIDOR... AS LIFT AND DEEP MOISTURE PLUME WILL BE SHIFTING EWD IN ADVANCE OF THE TROUGH. THE UPPER TROUGH IS EXPECTED TO PROGRESS EWD OVER THE CHSPK BAY IN THE AFTN. PRECIP CHANCES SHOULD END OVER THE MTS LATER IN THE MRNG AND AFTN AS SUBSIDENCE AND DRIER AIR IN WAKE OF THE TROUGH WORKS INTO THE AREA FROM WEST TO EAST. THE TIMING OF THE UPPER TROUGH PASSAGE MAY BE LATE ENOUGH IN THE DAY FOR THE SYNOPTIC LIFT TO COINCIDE WITH PEAK HEATING NEAR THE CHSPK BAY. SCT SHOWERS AND STORMS MAY TRY TO FOCUS ALONG A PRE-FRONTAL SFC TROUGH NEAR OR JUST EAST OF I-95 DURING THE AFTN. BOTH THE UPPER AND SFC TROUGH WILL MOVE EAST OF THE BAY BY THE EVE. PRIMARY COLD FRONT WILL ADVANCE SEWD TOWARD WRN MD OVNGT BEFORE THE FRONT JUMPS TO THE DOWNSTREAM SFC TROUGH FRI MRNG. 12Z NAM IS SLIGHTLY FASTER WITH SOUTHWARD PROGRESS OF THE COLD FRONT ON FRI THAN THE 12Z GFS AND MUCH FASTER THAN THE ECMWF. THIS WILL BE IMPORTANT FOR DETERMINING WHEN THE PUSH OF DRIER AIR BEHIND THE FRONT OCCURS. WITH A DECENT NWLY SURGE BEHIND THE FRONT (AT LEAST FOR THIS TIME OF YR)...TREND WAS TO BE MORE AGGRESSIVE WITH THE POST-FRONTAL DRYING. LOW CHANCE POPS NEAR THE FRONT CONFINED TO EXTREME SRN PORTIONS OF THE CWA FOR FRI. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... IN COMPARISON...THE XTNDD FCST IS SOMEWHAT BORING. SFC HIPRES BLDS ATOP CWFA THIS WKND. THE H5 RDG BLDS MON-TUE. LOOKING FOR 4 DAYS OF MOSUN-SUNNY SKIES AND CLR NGTS. DUE TO CNDN SOURCE RGN...TEMPS FOR THE WKND WL BE BLO CLIMO...W/ NICE DRY AIR TO BOOT. TEMPS DO CREEP UP AGN BY ELY NEXT WK...BUT ONLY TO SEASONABLE VALUES. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... SHOWERS AND STORMS THAT ARE DEVELOPING ALONG THE RIDGES THIS AFTN WILL BE SLOW TO ADVANCE FARTHER EWD...BUT MAY REACH CHO AND MRB BETWEEN 21Z-00Z. WHAT EVER IS LEFT OF THIS ACTIVITY WILL MOVE EWD LATER THIS EVE AND OVNGT TOWARD THE REST OF THE TERMINALS AS AN UPPER LOW APPROACHES FROM THE WEST. TEMPORARY VSBY RESTRICTIONS POSSIBLE AT ANY OF THE TERMINALS WITH HEAVIER SHOWERS AND STORMS. CLOUD COVER TNGT WILL LIMIT THE POTENTIAL FOR FOG/STRATUS OVNGT COMPARED TO IN RECENT NGTS. REDUCED VSBYS TO IFR DURING THE ERY MRNG AT CHO...WHERE THERE IS A BETTER CHANCE TO SEE SOME CLEARING OVNGT IN WAKE OF THE PRECIP. CHANCE FOR SHOWERS EXPECTED TO CONTINUE EAST OF THE BLUE RIDGE THU MRNG AS THE UPPER LOW MOVES THRU. ADDITIONAL SCT SHOWERS AND STORMS POSSIBLE IN THE ERN TERMINALS THU AFTN...WHERE A SFC TROUGH IS FCST TO DEVELOP. COLD FRONT MOVES THRU THU NGT-FRI MRNG. EXPECT THIS FROPA TO BE MAINLY DRY. NW FLOW PTTN CONTS INTO FRI. VFR INTO THE WKND. && .MARINE... RETURN FLOW AROUND OFFSHORE HIGH PRESSURE WILL PROVIDE A LGT SLY WIND AROUND 10 KT THRU THE REMAINDER OF THE AFTN. SLY CHANNELING MAY ENHANCE WINDS TO NEAR 15 KT TNGT IN THE MAIN STEM OF THE CHSPK BAY. SOUTHERLY FLOW WILL CONTINUE THROUGH THURSDAY AS A TROUGH OF LOPRES APPROACHES. WINDS WILL REMAIN AROUND 10 KT. A FEW TSTMS MAY CONTAIN GUSTY WINDS DURING THE AFTN. COLD FROPA LATE THU NGT AND FRI MRNG. NW WNDS WL PICK UP ELY FRI MRNG BHD FROPA...W/ NW WNDS CONTG THRU FRI. DONT THINK THAT WNDS WL REACH SCA CRITERIA ATTM...DO RECOGNIZE THAT IT MAY BE CLOSE. HIPRES WL BE BLDG THIS WKND. LGT NW WNDS SAT...VEERING SELY BY SUN. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && SYNOPSIS...JRK NEAR TERM...JRK SHORT TERM...JRK LONG TERM...HTS AVIATION...JRK/HTS MARINE...JRK/HTS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 454 PM EDT WED AUG 21 2013 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 221000- 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- 454 PM EDT WED AUG 21 2013 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...TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504- WVZ050>053-055-501>506-221000- 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- 454 PM EDT WED AUG 21 2013 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...TONIGHT NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
The Sterling radar (KLWX), 109 km away, was scanning. The volume nearest the first event began at 21:19 UTC.
5 thunderstorm wind. Local standard time, as filed.
There were a few signs down near mile marker 264 along Interstate 81.
There was a large tree branch that snapped.
There was a tree reported down blocking the Southbound side of Route 11 on the 16000 block.
There was a tree reported down on power lines on the 5500 Block of Singers Glen Road.
There were multiple tree limbs and branches down along Community Center Drive.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Virginia in 2013Every state in 2013This day in weather historyWarnings in Virginia, August 2013
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: 473646, 473647, 473648, 473650, 473649.