Scattered showers and isolated thunderstorms formed as an upper level trough swung through the northeast overnight. An abundance of moisture from persistent southerly flow led to enough instability to result in scattered convection and embedded stronger to severe thunderstorms.
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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.
Scattered showers and isolated thunderstorms formed as an upper level trough swung through the northeast overnight. An abundance of moisture from persistent southerly flow led to enough instability to result in scattered convection and embedded stronger to severe thunderstorms.
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 10, 8:30 PM EST, 5 hours 20 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
930 PM EDT MON AUG 10 2015
.SYNOPSIS...
AS LOW PRESSURE MOVES THROUGH THE GREAT LAKES...A WARM FRONT WILL
LIFT THROUGH THE AREA TONIGHT...FOLLOWED BY A COLD FRONT SWEEPING
EASTWARD ON TUESDAY. HIGH PRESSURE WILL THEN MOVE ACROSS THE MID-
ATLANTIC FROM WEDNESDAY INTO FRIDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
SHOWERS WILL OVERSPREAD THE ENTIRE REGION FROM WEST TO EAST
OVERNIGHT. A FEW RUMBLES OF THUNDER CANNOT BE RULED OUT BUT
OVERALL THE CONVECTIVE THREAT IS MARGINAL AT BEST. MOST AREAS WILL
PICK UP 0.25 TO 0.50 INCHES OF QPF WITH LOCALIZED HIGHER AMOUNTS
UP TO 1.0 INCH POSSIBLE. AM NOT EXPECTING FLOODING CONCERNS.
OVERNIGHT LOWS WILL BOTTOM OUT IN THE UPPER 60S IN MOST
LOCATIONS...EXCEPT LOWER TO MIDDLE 70S IN THE BALTIMORE AND
WASHINGTON DC METRO AREAS. SOME PATCHY FOG COULD ALSO DEVELOP
AFTER MIDNIGHT.
AFTER THE WARM FRONT LIFTS NORTH...THERE MAY BE A BIT OF A BREAK
IN THE PRECIPITATION LATER TUESDAY MORNING. BY THIS POINT THE
COLD FRONT WILL BE CROSSING THE APPALACHIANS AND REACHING
SOMEWHERE IN THE VICINITY OF I-81 BY MIDDAY. THERE WILL NOT BE A
LOT OF TIME FOR THE ATMOSPHERE TO RECOVER AND IT WILL LIKELY
REMAIN FAIRLY CLOUDY. HOWEVER STEEPER LAPSE RATES WILL ADVECT IN
ALOFT...RESULTING IN SOME INSTBY. DEEP LAYER SHEAR IS EXPECTED TO
BE 25-35 KT RANGE. SO SOME STRONGER STORMS COULD DEVELOP AS THE
FRONT HEADS EAST FROM THE BLUE RIDGE. AS LONG AS IT DRIES
OUT...HIGHS WILL REACH THE LOWER TO MID 80S.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
THE FRONT PUSHES EAST QUICKLY TUESDAY EVENING AND THE AREA WILL
DRY OUT OVERNIGHT. THE COOLER/DRIER AIR MAY NOT QUITE HAVE AN
EFFECT ON EASTERN AREAS WITH LOWS IN THE MID TO UPPER 60S
EXPECTED...ALTHOUGH WESTERN AREAS COULD DROP INTO THE 50S.
A LARGE AREA OF HIGH PRESSURE AT THE SURFACE WILL BUILD OVER THE
AREA FROM THE OHIO VALLEY ON WEDNESDAY INTO WEDNESDAY NIGHT.
ALOFT...A TROUGH AXIS AT 500 MB WILL PIVOT ACROSS THE AREA.
NORTHWEST FLOW AND PVA MAY SPAWN A FEW POP UP SHOWERS OVER THE
WESTERN RIDGES...OTHERWISE THE AREA WILL BE DRY AND MILD.
AS THE HIGH MOVES OVERHEAD AND RIDGING BUILDS ALOFT WEDNESDAY NIGHT
INTO THURSDAY...MOSTLY CLEAR AND DRY WEATHER IS EXPECTED.
TEMPERATURES WILL DROP TO SEVERAL DEGREES BELOW NORMAL DURING THIS
TIME.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
HIGH PRESSURE WILL MOVE OVER THE AREA THROUGH FRIDAY...BEFORE
MOVING OFFSHORE FRIDAY NIGHT INTO SATURDAY. A COLD FRONT WILL
APPROACH FROM THE NORTH ON SATURDAY...AND CROSS THE AREA THROUGH
SUNDAY. A FEW ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE OVER
NORTHWESTERN PARTS OF THE CWA DURING THIS TIME...BUT POTENTIAL
LIMITED MOISTURE MAY PRECLUDE BETTER COVERAGE.
HIGH PRESSURE LOOKS TO NOSE BACK INTO THE AREA LATE IN THE WEEKEND
INTO EARLY NEXT WEEK. TEMPERATURES SHOULD BE RIGHT AROUND NORMAL FOR
THIS TIME OF YEAR THROUGH THE WEEKEND...WITH HIGHS IN THE 80S AND
LOWS IN THE UPPER 50S AND 60S.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
CONDITIONS WILL DETERIORATE OVERNIGHT AND INTO TUESDAY MORNING.
MVFR TO IFR CIGS AND LOWERED VSBYS ARE LIKELY AT ALL TERMINAL
SITES. WIDESPREAD SHOWERS...PERHAPS A FEW RUMBLES OF THUNDER WILL
BE POSSIBLE OVERNIGHT. SOME PATCHY FOG WILL ALSO BE POSSIBLE.
SCATTERED SHOWERS AND STORMS POSSIBLE TUESDAY AFTERNOON AND
EVENING.
VFR EXPECTED WED-FRI AS HIGH PRESSURE MOVES ACROSS. NWLY
FLOW 10-15 KT WED...LIGHT/VARIABLE THU AS HIGH MOVES OVERHEAD THEN
SWLY AOB 10 KT FRI.
&&
.MARINE...
SOUTHERLY FLOW WILL PRODUCE SCA CONDITIONS TONIGHT ACROSS ALL THE
WATERS. THE GUSTS WILL LIKELY RELAX ON THE UPPER TIDAL POTOMAC AND
FAR NORTHERN BAY TUESDAY MORNING...BUT INCREASE AGAIN AFTER A COLD
FRONT PUSHES THROUGH TUESDAY EVENING. THE SCA HAS BEEN ADJUSTED
ACCORDINGLY. WIDESPREAD SHOWERS...PERHAPS A FEW RUMBLES OF
THUNDER ARE EXPECTED OVERNIGHT INTO TUESDAY.
SCA GUSTS COULD LINGER ON NWLY FLOW WEDNESDAY
MORNING...BUT SHOULD DIMINISH BELOW THRESHOLDS DURING THE DAY AS
HIGH PRESSURE BUILDS TOWARDS THE REGION. THE WEAK GRADIENT WILL
REMAIN OVER THE AREA THURSDAY INTO FRIDAY AS THE HIGH MOVES OVERHEAD.
&&
.TIDES/COASTAL FLOODING...
COASTAL FLOOD WARNINGS AND ADVISORIES HAVE BEEN ISSUED FOR MUCH OF
THE WATERS. ABOVE NORMAL TIDES EXPECTED ON THE NEXT HIGH TIDE
CYCLE. SOME MODERATE FLOODING MAY DEVELOP AT ANNAPOLIS.
A COLD FRONT WILL HELP DECREASE ANOMALIES BEGINNING TUESDAY
NIGHT.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...COASTAL FLOOD ADVISORY FROM 3 AM TO 9 AM EDT TUESDAY FOR
DCZ001.
MD...COASTAL FLOOD ADVISORY FROM 2 AM TO 11 AM EDT TUESDAY FOR
MDZ011-508.
COASTAL FLOOD ADVISORY UNTIL 4 AM EDT TUESDAY FOR MDZ017-018.
COASTAL FLOOD WARNING UNTIL 9 AM EDT TUESDAY FOR MDZ014.
VA...COASTAL FLOOD ADVISORY FROM 3 AM TO 9 AM EDT TUESDAY FOR
VAZ054.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT WEDNESDAY FOR ANZ531>534-
537>543.
COASTAL FLOOD ADVISORY FROM 2 AM TO 11 AM EDT TUESDAY FOR
ANZ538.
COASTAL FLOOD ADVISORY UNTIL 4 AM EDT TUESDAY FOR ANZ542.
SMALL CRAFT ADVISORY UNTIL 11 AM EDT TUESDAY FOR ANZ530-535-
536.
SMALL CRAFT ADVISORY FROM 10 PM TUESDAY TO 6 AM EDT WEDNESDAY
FOR ANZ530-535-536.
COASTAL FLOOD ADVISORY FROM 3 AM TO 9 AM EDT TUESDAY FOR
ANZ535.
&&
SYNOPSIS...ADS
NEAR TERM...KRW
SHORT TERM...ADS/DFH
LONG TERM...DFH
AVIATION...KRW/DFH
MARINE...KRW/DFH
TIDES/COASTAL FLOODING...KRWHAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 555 PM EDT MON AUG 10 2015 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-111200- 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-SOUTHERN BALTIMORE-PRINCE GEORGES- ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT-SOUTHEAST HARFORD- PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX- ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA- KING GEORGE- 555 PM EDT MON AUG 10 2015 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 A COASTAL FLOOD WARNING IS IN EFFECT FOR LOW LYING AREAS OF ANNE ARUNDEL COUNTY...PARTICULARLY ANNAPOLIS. MODERATE INUNDATION IS EXPECTED DURING THE OVERNIGHT HIGH TIDE CYCLE. COASTAL FLOOD ADVISORIES ARE IN EFFECT FOR WASHINGTON DC...SOUTHERN MARYLAND...BALTIMORE AND HARFORD COUNTIES. MINOR INUNDATION IS EXPECTED LATE TONIGHT INTO THE OVERNIGHT HIGH TIDE CYCLES. PLEASE REFER TO THE LATEST CFWLWX FOR FURTHER DETAILS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY COASTAL FLOOD WARNINGS AND ADVISORIES CONTINUE INTO MID MORNING TUESDAY. WEDNESDAY THROUGH SUNDAY...NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-111200- WASHINGTON-FREDERICK MD-CARROLL-NORTHERN BALTIMORE- EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY- NORTHWEST MONTGOMERY-CENTRAL AND SOUTHEAST MONTGOMERY- NORTHWEST HOWARD-CENTRAL AND SOUTHEAST HOWARD-NORTHWEST HARFORD- AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE- NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-ORANGE-CULPEPER- NORTHERN FAUQUIER-SOUTHERN FAUQUIER-WESTERN HIGHLAND- EASTERN HIGHLAND-WESTERN LOUDOUN-EASTERN LOUDOUN- NORTHERN VA BLUE RIDGE-CENTRAL VA BLUE RIDGE-HAMPSHIRE-MORGAN- BERKELEY-JEFFERSON-HARDY-WESTERN GRANT-EASTERN GRANT- WESTERN MINERAL-EASTERN MINERAL-WESTERN PENDLETON- EASTERN PENDLETON- 555 PM EDT MON AUG 10 2015 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...TUESDAY THROUGH SUNDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.
The Sterling radar (KLWX), 67 km away, was scanning. The volume nearest the first event began at 06:47 UTC.
1 thunderstorm wind. Local standard time, as filed.
A 10 inch in diameter tree limb was snapped near the intersection of Crain Hwy and Route 4. Reported by spotter PGE38.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2015Every state in 2015This day in weather historyWarnings in Maryland, August 2015
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: 593082.