On the afternoon of the 11th, thunderstorms with very heavy rainfall, frequent lightning, and damaging winds moved across north central Maryland. In Harford County, a downburst estimated between 60 and 70 MPH downed trees, damaged homes, and destroyed buildings at a marina about 4 miles east of Edgewood.
Every event with a place to put it; 6 filed by county or forecast zone are drawn at its center, in a lighter ring. 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.
On the afternoon of the 11th, thunderstorms with very heavy rainfall, frequent lightning, and damaging winds moved across north central Maryland. In Harford County, a downburst estimated between 60 and 70 MPH downed trees, damaged homes, and destroyed buildings at a marina about 4 miles east of Edgewood. The most concentrated area of damage was along the Bush River between Flying Point and Aberdeen Proving Grounds. Over 30 trees were downed in Flying Point Park. At the Flying Point Marina, a large pole barn was downed resulting in $100,000 damage. Small trees were downed and gutters were damaged just west of the park in the Harbor Oaks subdivision. A person on Flying Point Road observed a 6 foot wide waterspout moving west across the Bush River toward Flying Point during the height of the storm. Across from Flying Point on the other side of the river, numerous trees were downed in the Bush River Manor subdivision. Fifteen mobile homes in this community suffered damage from flying debris like metal supports from porches and pieces of skirting. One metal support rammed into a cinder support block under a trailer and pushed it out of alignment. The damage path continued south across Boyer Road to the Sod Run Wastewater Treatment Plant where roofing and flashing was ripped off a building. Airborne gravel and debris knocked out windows on several vehicles. Next to the plant, a cornfield was flattened, trees were downed, and a fence was blown over. Nearby on Aberdeen Proving Grounds, about 100 trees were downed and 75 trees were snapped north of Romney Creek. A wind gauge about a mile south of the downed trees recorded a gust of 40 MPH. The downburst apparently originated between the water treatment plant and Perryman Road. Heavy rainfall flooded roads in the Riverside, Edgewood, and Belcamp areas. Route 7 was closed when 4 feet of water covered the road. Several motorists were caught in rapidly rising water in Edgewood. A total of 4.65 inches of rain was recorded in Fallston and 2.7 inches was reported in Bel Air. A man climbing a ladder in his attic was struck by lightning in Bel Air. He felt the bolt enter his left hand then he slid down the ladder and called for help. He was treated for injuries to his palm, arm, shoulder, and chest. In Howard County, high water closed Route 29 at the intersection of Route 216. Six additional roads in the Elkridge area were closed by flooding. Heavy rainfall downed trees onto three roads in the Ellicott City and Lisbon areas. In Clarksville, a home sustained $100,000 damage from a lightning fire. A total of 2.54 inches of rain was recorded in Ellicott City. In Montgomery County, rainfall totals included 4.68 inches in Gaithersburg, 3.22 inches in Bethesda, 2.63 inches in Glenmont, and 2.60 inches in Rockville. In Gaithersburg, a large store was evacuated after excessive rainfall collected on its roof. A stream and wetland area flooded onto Clopper Road near I-270. Trees were downed along Rock Creek after it overflowed. Motorists were rescued from cars stalled in high water in several spots including Little Falls Parkway, River Road, Connecticut Avenue, and Beach Drive. Lightning struck a home in Gaithersburg causing minor damage. In Prince George's County, four people were killed in weather related traffic accidents.
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 11, 1:05 PM EST, 40 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON 205 PM EDT SAT AUG 11 2001 WESTERLIES REMAIN JUST N OF THE AREA OVR THE NEXT 24 HOURS. BY SUN AND MON...UPR LVL RDG DEVELOPS OVR THE WRN U.S. WITH A DOWNSTREAM TROF DEVELOPING OVR THE ERN U.S. FNT REMAINS STALLED JUST TO OUR N SEPARATING THE COOL DRY AIR TO THE N OF THE FNT FROM THE VERY MOIST/HUMID AIR MASS OVR OUR AREA. WITH THE FNT ON THE SRN EDGE OF THE WESTERLIES...PARALLEL TO THE UPR LVL FLOW...IT WILL NOT MOVE MUCH THROUGH SUN. MEANWHILE...WEAK WAVES OF LOW PRES WILL MOVE EWD ALG THE FNT. BY SUN NGT AND MON...WITH HGTS FALLING OVR THE ERN U.S. AND THE UPR LVL TROF DEEPENING...THE FNT WILL FINALLY START TO MOVE SWD THRU THE AREA WITH THE FNT THRU THE CWA BY 00Z TUE. PWS IN EXCESS OF 2 INCHES OVR THE AREA THRU MON MORNING WITH PWS SLOWLY COMING DOWN LATE MON AS THE FNT PUSHES THRU THE AREA. PLENTY OF MOISTURE TO WORK WITH THE NEXT COUPLE OF DAYS. THIS COMBINED WITH AFTRN HEATING/INSTABILITY WILL RESULT IN THE DVLPMT OF CONVECTION ESP ALG THE RDGS AND ALG VARIOUS MESOSCALE BOUNDARIES. IN ADDTN...AS THE FNT SAGS SWD SUN NGT AND MON...THE FNT WILL ACT AS AN ADDITIONAL FOCUS FOR CONVECTION. WILL GO WITH LIKELY POPS THIS EVE (MAINLY BFR MIDNIGHT) AND LIKELY POPS AGAIN ON SUN BUT SAY MAINLY AFTRN. WITH FNT SLOWLY SAGGING SWD INTO THE AREA MON NGT WILL CONTINUE WITH LIKELY POPS. FNT SHOULD BE THRU THE NWRN ZNS BY 18Z MON SO WILL ONLY MENTION CHC MORNING SHRA NW ZNS. ELSEWHERE...WILL GO WITH 60 POPS FOR SHRA/TSRA. WITH HIGH PWS AND SLOW MOVEMENT OF CELLS...BIGGEST THREAT THE NEXT DAY OR SO FROM CONVECTION WILL BE FOR HEAVY RAIN AND SCT FLASH FLOODING. HOWEVER...CAN NOT PIN POINT ONE AREA THAT IS MORE VULNERABLE THAN THE REST OF THE AREA SO NO WATCH WILL BE ISSUED. AS FAR AS SVR POTENTIAL IS CONCERNED THE NEXT COUPLE OF DAYS...WET BULB ZERO HEIGHTS REMAIN HIGH SO A VERY LOW THREAT OF LARGE HAIL. AS FAR AS STRONG WINDS ARE CONCERNED...WE WILL HAVE WEAK SHEAR AND LGT WINDS ALOFT SO NOTHING MORE THAN AN ISOLD PULSE TYPE SVR EXPECTED (IF THAT). FNT CLEARS THE AREA BY 00Z TUE AND DRIER AIR MAKES ITS WAY INTO THE AREA TUE/WED AS HIGH PRES BUILDS INTO THE AREA. NEXT CDFNT THRU HERE ON FRI W/ SHRA/TSRA. FCSTID = 15 / DMW DCA 75 89 76 87 / 60 60 60 60 BWI 72 88 72 86 / 60 60 60 60 MRB 72 86 70 85 / 60 60 60 40 IAD 73 89 72 86 / 60 60 60 60 CHO 73 87 72 86 / 60 60 60 60 HGR 69 85 68 84 / 60 60 60 40 NHK 75 88 75 86 / 60 60 60 60 W99 72 86 70 85 / 60 60 60 40 .LWX... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE.
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
1115 AM EDT SAT AUG 11 2001
TIME(EDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0350 PM LANDOVER MD WIND DAMAGE
08/10/01 PRINCE GEORGES TREES AND WIRES DOWN
0427 PM WARRENTON VA WIND DAMAGE
08/10/01 FAUQUIER LARGE TREES DOWN
REPORTED BY METEOROLOGIST
0440 PM NEW BALTIMORE VA WIND DAMAGE
08/10/01 PRINCE WILLIAM LARGE TREES DOWN
REPORTED BY SPOTTERS
0450 PM CITY OF MANASSAS VA WIND DAMAGE
08/10/01 CITY OF MANASSAS TWO TREES DOWN
REPORTED BY EMERGENCY
MANAGEMENT
0458 PM GAINESVILLE VA WIND DAMAGE
PRINCE WILLIAM TREES DOWN AND A TRAILER
FLIPPED OVER
0524 PM 5 N FREDERICKSBURG VA WIND DAMAGE
08/10/01 STAFFORD TREES DOWN IN MICROBURST
PATTERN NEAR RT 17 AND I95
REPORTED BY PILOT REPORTED BY PILOT
0630 PM COUNTYWIDE MD WIND DAMAGE
08/10/01 CALVERT EOC HAD SEVERAL REPORTS OF
TREES DOWN COUNTYWIDE.
0645 PM 5 E OF LA PLATA MD WIND DAMAGE
08/10/01 CHARLES TREES DOWN ON ROUTE 6
5 MILES E OF LA PLATA
WALSTONPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON
1115 AM EDT SAT AUG 11 2001
TIME(EDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....
0350 PM LANDOVER MD WIND DAMAGE
08/10/01 PRINCE GEORGES TREES AND WIRES DOWN
0427 PM WARRENTON VA WIND DAMAGE
08/10/01 FAUQUIER LARGE TREES DOWN
REPORTED BY METEOROLOGIST
0440 PM NEW BALTIMORE VA WIND DAMAGE
08/10/01 PRINCE WILLIAM LARGE TREES DOWN
REPORTED BY SPOTTERS
0450 PM CITY OF MANASSAS VA WIND DAMAGE
08/10/01 CITY OF MANASSAS TWO TREES DOWN
REPORTED BY EMERGENCY
MANAGEMENT
0458 PM GAINESVILLE VA WIND DAMAGE
PRINCE WILLIAM TREES DOWN AND A TRAILER
FLIPPED OVER
0524 PM 5 N FREDERICKSBURG VA WIND DAMAGE
08/10/01 STAFFORD TREES DOWN IN MICROBURST
PATTERN NEAR RT 17 AND I95
REPORTED BY PILOT
0630 PM COUNTYWIDE MD WIND DAMAGE
08/10/01 CALVERT EOC HAD SEVERAL REPORTS OF
TREES DOWN COUNTYWIDE.
0645 PM 5 E OF LA PLATA MD WIND DAMAGE
08/10/01 CHARLES TREES DOWN ON ROUTE 6
5 MILES E OF LA PLATA
WALSTONThe national radar mosaic for the moment the first event began.
3 flash flood, 2 lightning, 1 thunderstorm wind, 1 waterspout. Local standard time, as filed.
A downburst estimated between 60 and 70 MPH downed several trees and damaged the Flying Point Marina.
A microburst spawned a small waterspout on the Bush River.
Several roads including Route 7 were flooded.
A man was struck by lightning while climbing a ladder in his attic.
Several roads were flooded after streams overflowed.
A home was damaged by lightning.
Several roads were closed by flooding and heavy rainfall downed trees.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2001Every state in 2001This day in weather historyWarnings in Maryland, August 2001
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: 5263701, 5263702, 5263703, 5266930, 5265437, 5265439, 5265438.