A cold front combined with an upper level low pressure system to trigger numerous showers and thunderstorms central Maryland during the afternoon and evening of July 29th. Several of these storms became severe, producing damaging winds in Prince Georges and Frederick Counties.
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.
A cold front combined with an upper level low pressure system to trigger numerous showers and thunderstorms central Maryland during the afternoon and evening of July 29th. Several of these storms became severe, producing damaging winds in Prince Georges and Frederick Counties.
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 Jul 29, 10:30 AM EST, 2 hours 10 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1130 AM EDT SUN JUL 29 2007 .SYNOPSIS... A STALLED FRONT ACROSS NORTHERN VIRGINA WILL MOVE SLOWLY SOUTH AND TRACK SOUTH OF THE REGION BY TUESDAY NIGHT. IN THE MEANTIME...SHOWERS AND THUNDERSTORMS WILL CONTINUE TO TRACK ALONG THE FRONTAL BOUNDARY...SOME THUNDERSTORMS COULD PRODUCE LOCALLY HEAVY RAIN TODAY. HIGH PRESSURE WILL BUILD INTO THE AREA FOR TUESDAY NIGHT AND KEEP THE AREA MOSTLY DRY INTO THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... WEAK BOUNDARY HAS SLIPPED THROUGH BALTIMORE AND DC...AND WAS LOCATED FROM ABOUT THE NORTHERN CHESAPEAKE BAY TO LOWER SOUTHERN MARYLAND TO CENTRAL VIRGINIA LATE THIS MORNING. EARLIER MASS OF CONVECTION THAT AFFECTED NORTHERN MARYLAND HAS SHIFTED EAST...BUT ADDITIONAL ACTIVITY IS ALREADY BEGINNING TO DEVELOP OVER MARYLAND. DONT EXPECT THE BOUNDARY TO MOVE MUCH FOR THE REST OF TODAY. IT WILL SERVE AS ONE FOCUSING MECHANISM FOR CONVECTION...AS WILL THE UPPER LEVEL TROUGH OVER THE AREA. OTHER MESOSCALE INFLUENCES WILL BE AT PLAY TOO. SHOULD EXPERIENCE A DECENT COVERAGE OF CONVECTION THIS AFTERNOON...HIGHEST ACROSS NORTH AND WEST MARYLAND AND THE EASTERN WEST VIRGINIA PANHANDLE (BASED ON RADAR TRENDS AND 12Z GUIDANCE) WHERE LIKELY POPS WILL BE IN PLACE. CHANCE POPS WILL RESIDE ELSEWHERE. 12Z KIAD RAOB MODIFIED FOR 86/68 SHOWED A VERY MOIST AND MODERATELY UNSTABLE ATMOSPHERE. PRECIPITABLE WATER VALUE HAD INCREASED TO ABOUT 1.9 INCHES...AND MODIFICATION YIELDED ABOUT 2500 J/KG OF SURFACE BASED CAPE. 0 TO 6 KM SHEAR...WHILE IN THE WEAK CATEGORY...WAS BIT BETTER THAN RECENT DAYS TOO /UP TO 25 KT/. THEREFORE...IN ADDITION TO A HEAVY RAINFALL THREAT DUE TO HIGH PRECIPITABLE WATER VALUES AND RELATIVELY SLOW STORM MOTION (10 KT OR LESS)...THERE WILL BE AN ISOLATED SEVERE RISK AS WELL MAINLY DUE TO THE HIGH CAPE ENVIRONMENT. THIS COULD SUPPORT ISOLATED DAMAGING WET MICROBURST WINDS. HWO WILL CONTINUE TO HIGHLIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... COLD FRONT WILL BEGIN TO PUSH SOUTH ACROSS REGION AS ANOTHER SURFACE LOW TRACKS NORTHEAST ON MONDAY. PWATS BEGIN TO LOWER SO THREAT OF HEAVY RAIN REDUCED BUT STILL AN ISOLATED SEVERE STORM POSSIBLE MONDAY AFTERNOON. WILL KEEP SLIGHT CHC POPS IN FORECAST TONIGHT AND THEN INCREASE TO CHANCE FOR MONDAY WITH NEXT SFC WAVE TRACKING NE ACROSS EASTERN ZONES. MET MOS LOOKED TOO LOW...MOST MOS GNDC COMPARABLE. BLENDS TAKEN...WEIGHTED TWD HIER VALUES FOR BOTH MIN AND MAX T. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... LONG TERM... THE BIG CHANGE TO THE EXTENDED IS THE INCREASE IN DAILY HIGHS THROUGHOUT THE FORECAST PERIOD. ALL LATEST MED AND LONG RANGE GUIDANCE WENT UPWARDS OF 5 DEGREES WARMER THAN PREV RUNS FROM TUES THRU SAT OF NEXT WEEK. GFS DEVELOPS A CLOSED UPPER HIGH PRESSURE AREA OVER THE MID MISSISSIPPI VALLEY DURING THE EARLY PART OF THE WEEK. AS THE RIDGE BUILDS OVER THE GREAT LAKES REGION OVER THE MIDDLE PART OF THE WEEK...THE RESULT WILL BE A REINTRODUCTION TO SUMMERLIKE TEMPS ACROSS THE MID ATLANTIC. THE UPPER TROUGH WILL SLOWLY MOVE OFF THE ATLANTIC AND NORTHEAST COAST THROUGH THE EARLY PART OF THE WEEK...KEEPING A SHARP GRADIENT OF CLOUD COVER AND POSSIBLE PRECIP FOR REGION CLOSER TO THE COAST MON AND TUES...WITH DRIER CONDITIONS...CLEARING SKIES AND WARMER TEMPS INLAND. THE NAM ESSENTIALLY DRIES HAS AN EVEN SLOWER EXIT FOR THE UPPER TROF...THOUGH IT DRIES OUT THE REGION FOR EFFICIENTLY WITH A FEW DIURNAL SHRA/TSRA ACTIVITY DEVELOPING AND PUSHING SOUTHWARD THROUGH THE WESTERN HALF OF THE CWA. IT LOOKS AS THOUGH THE UPPER LOW OVER THE TX/LA REGION WILL NOT BE OF MUCH CONSEQUENCE TO AREAS OUTSIDE THE DEEP SOUTH. BESIDES AN EFFICIENT MOISTURE RETURN THROUGHOUT THE SOUTHEAST AND SCATTERED ACTIVITY IN THE WARM CORRIDOR SOUTH OF THE STATIONARY FRONT...THE SFC HIGH PRESSURE WILL DRY OUT THE OHIO RIVER VALLEY INTO THE MID ATLANTIC FOR MUCH OF NEXT WEEK...INTO THE LATTER PART OF THE WEEK. LATEST GFS RUN KEEPS THE STRONG UPPER CENTRAL CANADIAN TROF WELL TO THE NORTH...WITH THE ASSOCIATED COLD FRONT PASSING TO THE NORTH BY THE END OF NEXT WEEK...WEAKENING AS ZONAL FLOW DEVELOPS ACROSS THE REGION...BRINGING MORE STABILITY TO THE REGION UNTIL ANOTHER POSSIBLE WAVE DEVELOPS ACROSS THE UPPER MIDWEST BY THE END OF NEXT WEEKEND. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... SHOWER AND THUNDERSTORM COVERAGE WILL INCREASE THROUGH THIS AFTERNOON. WILL LIKELY HIT MOST TAFS INCLUDING THE HUBS HARDER IN THE 18Z ISSUANCE WITH AT LEAST SOME MVFR CONDITIONS. A WEAK FRONT HAS SLIPPING SOUTHEAST THROUGH THE TERMINALS...SO WINDS WILL PRIMARILY BE FROM THE EAST OR NORTHEAST TODAY. LCL RESTRICTIONS W/IN ANY TSTM FOR MONDAY ALSO. VFR CONDITIONS EXPECTED TUE-FRI. && .MARINE... WINDS MAINLY FROM THE EAST FOR THE REST OF TODAY...BUT 10 KT OR LESS. NO FLAGS XPCTD...BUT TSRA CUD YIELD LCLLY HIER WNDS/WVS... AND MAY NECESSITATE SMW. NO FLAGS EXPECTED IN THE EXTENDED WITH HIGH PRESSURE BUILDING INTO AREA. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && SYNOPSIS...RW NEAR TERM...BPP SHORT TERM...RW LONG TERM...GMS AVIATION...BPP/GMS/RW MARINE...BPP/GMS/RW
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1134 AM EDT SUN JUL 29 2007 ANZ530>537-DCZ001-MDZ003>007-009>011-013-014-016>018-501-502- VAZ021-025>031-036>042-050>057-WVZ050>055-501>504-301000- 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- DISTRICT OF COLUMBIA-WASHINGTON-FREDERICK MD-CARROLL- NORTHERN BALTIMORE-HARFORD-MONTGOMERY-HOWARD-SOUTHERN BALTIMORE- PRINCE GEORGES-ANNE ARUNDEL-CHARLES-ST. MARYS-CALVERT- EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-HIGHLAND- AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE- NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-FAUQUIER-LOUDOUN- ORANGE-CULPEPER-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX- ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA- KING GEORGE-HAMPSHIRE-MORGAN-BERKELEY-JEFFERSON-PENDLETON-HARDY- WESTERN GRANT-EASTERN GRANT-WESTERN MINERAL-EASTERN MINERAL- 1134 AM EDT SUN JUL 29 2007 THIS HAZARDOUS WEATHER OUTLOOK IS FOR MARYLAND WEST OF THE EASTERN SHORE INCLUDING THE CHESAPEAKE BAY AND EAST OF GARRETT COUNTY...EASTERN WEST VIRGINIA...NORTHERN AND CENTRAL VIRGINIA... WASHINGTON DC AND THE TIDAL POTOMAC RIVER. .DAY ONE...THIS AFTERNOON AND TONIGHT SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED ACROSS THE REGION THIS AFTERNOON. DUE TO HIGH MOISTURE CONTENT AND WEAK STEERING WINDS ALOFT...STORMS WILL MOVE SLOWLY AND WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL. IN ADDITION...ONE OR TWO ISOLATED SEVERE THUNDERSTORMS WILL BE POSSIBLE. DAMAGING WINDS WILL BE THE PRIMARY THREAT IN ANY SEVERE THUNDERSTORM. .DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED AGAIN MONDAY. A FEW OF THE STORMS MAY BECOME SEVERE WITH A THREAT OF LOCALLY DAMAGING WINDS...HAIL...AND HEAVY RAIN. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT ANTICIPATED THROUGH TONIGHT.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 911 AM EDT SUN JUL 29 2007 MDZ007-291400- HARFORD MD- 911 AM EDT SUN JUL 29 2007 ...STRONG THUNDERSTORM TO AFFECT NORTHERN HARFORD COUNTY... AT 911 AM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM NEAR CARDIFF...MOVING EAST AT 5 MPH. THIS STORM WILL BE CAPABLE OF PRODUCING SMALL HAIL AND WIND GUSTS TO 40 MPH...IN ADDITION TO FREQUENT LIGHTNING AND HEAVY RAINFALL. THE COMMUNITIES OF SCARBORO AND DARLINGTON WILL BE AFFECTED BY THIS STORM. PELOQUIN
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
944 AM EDT SUN JUL 29 2007
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1100 PM TSTM WND DMG ROMNEY 39.35N 78.76W
07/28/2007 HAMPSHIRE WV TRAINED SPOTTER
TREES DOWN
0625 AM TSTM WND DMG BEL AIR 39.53N 76.35W
07/29/2007 HARFORD MD EMERGENCY MNGR
ROOF TORN OFF BUILDING IN DOWNTOWN BEL AIR.
&&
HTSSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1244 PM EDT SUN JUL 29 2007 WVZ054-291730- PENDLETON WV- 1244 PM EDT SUN JUL 29 2007 ...STRONG THUNDERSTORM TO AFFECT EASTERN PENDLETON COUNTY... AT 1244 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM 3 MILES NORTHEAST OF DEER RUN...NEARLY STATIONARY. THIS STORM WILL PRODUCE TORRENTIAL DOWNPOURS...AND MAY ALSO PRODUCE SMALL HAIL AND WIND GUSTS TO 40 MPH. THE COMMUNITY OF DEER RUN WILL BE AFFECTED BY THIS STORM. PELOQUIN
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1258 PM EDT SUN JUL 29 2007 DCZ001-MDZ013-291745- DISTRICT OF COLUMBIA DC-PRINCE GEORGES MD- 1258 PM EDT SUN JUL 29 2007 ...STRONG THUNDERSTORM TO AFFECT PORTIONS OF THE DISTRICT OF COLUMBIA AND WESTERN PRINCE GEORGES COUNTY... AT 1258 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM NEAR BOLLING AIR FORCE BASE...MOVING EAST AT 5 MPH. THIS STORM WILL BE CAPABLE OF PRODUCING VERY HEAVY RAINFALL...FREQUENT CLOUD TO GROUND LIGHTNING STRIKES AND WIND GUSTS TO 35 MPH. THE COMMUNITIES OF OXON HILL...MARLOW HEIGHTS...CORAL HILLS...CAMP SPRINGS...ANDREWS AFB...FRIENDLY AND CLINTON WILL BE AFFECTED BY THIS STORM. PELOQUIN
The Sterling radar (KLWX), 47 km away, was scanning. The volume nearest the first event began at 17:39 UTC.
3 thunderstorm wind. Local standard time, as filed.
An off duty NWS Employee reported large tree branches down in Oxon Hill, MD.
Law Enforcement reported trees down in the city of Frederick as well as the southeast section of the county.
Law Enforcement reported trees down in near Maugansville, MD.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2007Every state in 2007This day in weather historyWarnings in Maryland, July 2007
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: 47614, 47612, 47613.