A strong cold front combined with a humid and unstable air mass across the Mid Atlantic on August 9th. Scattered showers and thunderstorms developed across western and central Maryland during the late morning and spread east towards the Baltimore metro and into lower southern Maryland during the early and mid afternoon.
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 strong cold front combined with a humid and unstable air mass across the Mid Atlantic on August 9th. Scattered showers and thunderstorms developed across western and central Maryland during the late morning and spread east towards the Baltimore metro and into lower southern Maryland during the early and mid afternoon. Several of these storms became severe, producing large hail and damaging winds that downed trees and power lines.
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 9, 9:13 AM EST, 1 hour 17 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1013 AM EDT THU AUG 9 2007 .SYNOPSIS... A HUMID AIRMASS WILL REMAIN OVER THE AREA TODAY ALTHOUGH TEMPERATURES WILL BE COOLER. A COLD FRONT WILL APPROACH THE AREA LATE TODAY AND TRACK SOUTH OF THE REGION BY LATE FRIDAY. HIGH PRESSURE WILL BUILD OVER THE AREA FOR THE WEEKEND. ANOTHER COLD FRONT WILL TRACK ACROSS THE AREA LATE MONDAY INTO TUESDAY. HIGH PRESSURE WILL RETURN FOR MID WEEK. && .NEAR TERM /THROUGH TONIGHT/... HV COORDINATED SVR TSTM WTCH W/ SPC BASED ON STRONG CELLS IN VCNTY JST MOVG SEWD ALONG STATIONARY BNDRY. W/ THIS MUCH PTNL ENERGY AVBL AND NO CAP IN EITHER OUR OR APG SNDGS STORMS WL BE ABLE TO GROW. WOODY && .SHORT TERM /FRIDAY/... INTERESTING FORECAST FOR THIS AFTERNOON AND TONIGHT. CURRENT THINKING WOULD SUGGEST WE WILL HAVE TWO ROUNDS OF CONVECTION. THE FIRST ROUND WILL DEVELOP AS WIDELY SCATTERED THUNDERSTORMS THIS AFTERNOON. CONVECTIVE TEMPS SHOULD BE QUICKLY REACHED. SREF ALSO FORECASTING A BETTER THAN 50 PERCENT CHANCE OF CAPE GREATER THAN 2000 J/KG. LAPSE RATES WILL ALSO STEEPEN WITH A PUSH OF DRY AIR ALOFT INTO AREA. THE SECOND ROUND OF CONVECTION WILL OCCUR WITH TRAILING TROF AXIS FROM SURFACE LOW MOVING ACROSS PA TONIGHT. STORM MOVEMENT WILL BE SE AT 15 MPH. FORECAST WINDS UNI-DIRECTIONAL WITH WEAK SHEAR. MAIN THREAT FROM AFTERNOON AND EVENING CONVECTION WILL BE VERY HEAVY RAIN WITH PWATS JUST OVER 2.00 INCHES. POSSIBLE BOW-TYPE STRUCTURES IF WE GET A ORGANIZED LINE/S FORMING THIS EVENING. ISOLATED DAMAGING WINDS AND HAIL POSSIBLE. ITS QUITE POSSIBLE CONVECTION COULD CONTINUE THROUGH LATE TONIGHT. NAM INDICATES A SECONDARY MCS WILL PASS BY TO OUR NORTH AFTER MIDNIGHT. SPC HAS OUR AREA OUTLINED UNDER SLIGHT RISK FOR SEVERE. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... RESIDUAL SCATTERED CONVECTION AND LIGHTER ACTIVITY WILL PUSH SE ACROSS THE MID ATLANTIC LATE FRI INTO EARLY SAT MORN AHEAD OF THE UPPER TROF WHICH QUICKLY EXISTS THE COAST DURING THE DAY SAT. SFC HIGH PRESSURE BUILDS INTO THE EASTERN GREAT LAKES AND NORTHEAST ON SUNDAY. RAISED TEMPS SLIGHTLY FOR THE WEEKEND AS HIGH PRESSURE APPROACHES AND INFLUENCES THE AREA MORE THAN PREVIOUSLY SHOWN. HUMIDITY LEVELS ARE NOT EXPECTED TO FLUCTUATE MUCH DURING THE EXTENDED...WITH SOUTHERN STREAM RETURN FLOW UP AND ALONG THE ATLANTIC COAST THRU MUCH OF NEXT WEEK. GFS DEVELOPS AN MCS OVER THE UPPER MIDWEST THAT CONTINUES ALL THE WAY TO THE EAST COAST...WHILE CONJOINING WITH THE BOOKEND OF WEAKENING COLD FRONT OVER THE LOWER GREAT LAKES REGION. THE MODEL DEVELOPS CONVECTION IN THE LEE OF THE BLUE RIDGE...FROM MD TO SC. THIS DOES NOT LOOK TO BE A PLAUSIBLE SCENARIO...THOUGH ANY AMOUNT OF MID AND UPPER LEVEL ENERGY THAT SKIRT ACROSS THE REGION MIGHT BE RESPONSIBLE FOR ISOLATED ACTIVITY THROUGHOUT THE MID ATLANTIC MON AND TUES OF NEXT WEEK. AS THIS WEAK COLD FRONT IS MAKING A SLOW EXIT OFF THE COAST...ANOTHER UPPER WAVE WILL BEGIN MOVING ACROSS THE GREAT LAKES...WITH ANOTHER WEAK SFC BOUNDARY MOVING OFF TO THE NORTH AND EAST. ONE KEY FEATURE THAT WILL BE A MAJOR PLAYER IN NEXT WEEK/S CONDITIONS IS THE POSITION OF THE UPPER HIGH OVER THE CENTRAL PLAINS. LATEST LR MODELS ARE BRINGING THE HIGH CENTER FURTHER SOUTH AND WEST...WHICH WOULD BE MORE FAVORABLE FOR AN ACTIVE SCENARIO OVER THE MID ATLANTIC THROUGH LATE NEXT WEEK. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... SCATTERED THUNDERSTORMS TO DEVELOP ACROSS ALL TERMINALS THIS AFTERNOON AND EVENING. DAMAGING WINDS PSBL. SHOULD REMAIN DRY OVER THE WEEKEND. NEXT COLD FRONT AND ASSOCIATED THUNDERSTORMS... WILL TRACK INTO AREA LATE MONDAY INTO TUESDAY. && .MARINE... A WEAK BOUNDARY WILL REMAIN OVER THE WATERS WILL BE THE FOCUS FOR AFTERNOON AND EVENING THUNDERSTORMS...ESPECIALLY ACROSS THE NORTHERN BAY. A COLD FRONT WILL PASS THROUGH LATER ON FRIDAY...THEN HIGH PRESSURE WILL BUILD IN BEHIND THIS FRONT FOR THE WEEKEND THROUGH EARLY NEXT WEEK. ANOTHER COLD FRONT WILL APPROACH AREA LATE MONDAY AND TUESDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1039 AM EDT THU AUG 9 2007 ANZ530>537-DCZ001-MDZ003>007-009>011-013-014-016>018-501-502- VAZ021-025>031-036>042-050>057-WVZ050>055-501>504-101045- 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- 1039 AM EDT THU AUG 9 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...TODAY AND TONIGHT THE COMBINATION OF HIGH HUMIDITY...HOT TEMPERATURES AND A WEAK FRONT OVER THE AREA WILL TRIGGER STRONG THUNDERSTORMS LATE THIS MORNING AND THIS AFTERNOON. A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR CENTRAL MARYLAND...THE EASTERN PANHANDLE OF WEST VIRGINIA... NORTHERN VIRGINIA..AND THE DISTRICT OF COLUMBIA. THE POTOMAC RIVER AND THE NORTHERN CHESAPEAKE BAY ARE ALSO AT RISK. VERY HEAVY RAINFALL AND DAMAGING WINDS ARE THE MAIN THREATS WITH THESE STORMS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY A COLD FRONT WILL SWEEP INTO EASTERN VIRGINIA...MARYLAND AND PORTIONS OF THE CHESAPEAKE BAY FRIDAY AFTERNOON AND TRIGGER THUNDERSTORMS. A FEW STORMS COULD BE SEVERE. .SPOTTER INFORMATION STATEMENT... SKYWARN ACTIVATION HAS BEEN MADE.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1040 AM EDT THU AUG 9 2007 MDZ003>005-009-502-VAZ042-WVZ051>053-091700- WASHINGTON MD-CARROLL MD-FREDERICK MD-MONTGOMERY MD-LOUDOUN VA- JEFFERSON WV-BERKELEY WV-MORGAN WV-CENTRAL AND EASTERN ALLEGANY MD- 1040 AM EDT THU AUG 9 2007 ...SEVERE WEATHER LIKELY TO IMPACT NORTH CENTRAL MARYLAND...EXTREME EASTERN WEST VIRGINIA...AND EXTREME NORTHERN VIRGINIA BETWEEN 11:00 AM AND 1:00 PM... AT 1040 AM EDT...A LARGE THUNDERSTORM COMPLEX WITH A HISTORY OF PRODUCING WIND DAMAGE AND FLASH FLOODING WAS MOVING NORTHWEST TO SOUTHEAST ACROSS SOUTHERN PENNSYLVANIA NEAR EVERETT AND MCCONNELLSBURG. THIS COMPLEX WILL REACH THE HAGERSTOWN MARYLAND AND BERKELEY SPRINGS WEST VIRGINIA AREA AROUND 11:15 AM...FREDERICK MARYLAND AND NORTHERN LOUDOUN COUNTY VIRGINIA AROUND NOON...AND THE WESTERN PORTION OF THE BALTIMORE METROPOLITAN AREA AROUND 1:00 PM. DAMAGING WIND AND FREQUENT CLOUD TO GROUND LIGHTNING WILL BE LIKELY AS THESE STORMS PASS THROUGH THE REGION. RESIDENTS IN THESE AREAS SHOULD REMAIN ALERT IN THE LIKELY CASE WARNINGS ARE ISSUED...AND BE PREPARED TO TAKE SHELTER. A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR THIS ENTIRE AREA UNTIL 4:00 PM.
The Sterling radar (KLWX), 75 km away, was scanning. The volume nearest the first event began at 15:29 UTC.
6 thunderstorm wind. Local standard time, as filed.
Washington County Emergency Management reported a power line down in Halfway, MD.
A newspaper reported trees down on West Second Street near Upper College Terrace in downtown Frederick, MD.
Carroll County Emergency Management reported trees down on Clear Ridge Road in New Windsor. Law Enforcement reported trees and power lines down on Little Town Pike and Gorsuch Road in Westminster.
St. Mary's County Emergency Management reported trees down on Baptist Church Road in Mechanicsville, MD.
The Fire and Rescue Department reported trees down on power lines on Route 77 and Old Mill Road west of Rocky Ridge, MD.
The local Fire and Rescue reported trees and wires down in Westminster, 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, August 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: 51836, 51837, 51838, 51841, 51839, 51840.