Abnormally moist atmosphere across the mid-Atlantic allowed showers and thunderstorms to produce exceptional rainfall rates across portions of Maryland as the remnants of Tropical Depression Lee interacted with a nearly stationary boundary near the Mason-Dixon line. Major flooding and flash flooding occurred in numerous areas.
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.
Abnormally moist atmosphere across the mid-Atlantic allowed showers and thunderstorms to produce exceptional rainfall rates across portions of Maryland as the remnants of Tropical Depression Lee interacted with a nearly stationary boundary near the Mason-Dixon line. Major flooding and flash flooding occurred in numerous areas. The highest rainfall and worst flooding happened in a band from Charles County northeastward into Baltimore County. The highest measured rainfall report during this period was 10.70 inches in Anne Arundel County.
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 Sep 7, 2:48 AM EST, 6 hours 34 minutes earlier.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
348 AM EDT WED SEP 7 2011
.SYNOPSIS...
LOW PRESSURE OVER EASTERN TENNESSEE AND AN ASSOCIATED WARM FRONT
ACROSS NORTH CAROLINA WILL SLOWLY LIFT NORTH ACROSS THE AREA
TODAY. TROPICAL MOISTURE WILL OVERRUN THE BOUNDARY CAUSING LOCALLY
HEAVY RAIN. A PROLONGED PERIOD OF RAIN WILL LINGER THROUGH MUCH OF
THE WORK WEEK...AS THE LOW LINGERS IN THE OHIO VALLEY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SFC LOPRES FM THE FORMER TS LEE IN WRN VA ELY THIS MRNG. BASED ON
WATER VAPOR LOOP...THE CIRCULATION ALOFT CENTERED IN THE TN VLY. THE
MOST CONCENTRATED AREA OF ASSOC PCPN HAS LIFTED NWD INTO PA ATTM.
HWVR...THERE/S STILL A FEEDER BAND STRETCHING SWD ACRS THE WRN
CWFA...BTWN LYH-RIC...AND DOWN ACRS ERN NC. THIS ZONE APPEARS TO BE
REPRESENTED IN THE SFC ANALY IN A WEAKNESS IN THE PRES PTTN. THERE
ARE TWO OTHER ZONES OF CONCERN NOTED FM THIS ANALY...NEAR THE BAY
WHERE NLY FLOW AND MOIST ELY ONSHORE FLOW COLLIDE /DEWPT DIFF ARND
10F/... AND ALSO ACRS NC WHERE A WK WMFNT EXISTS.
THE LOWS /SFC AND ALOFT/ WL LIFT NWD TDA. XPCT RICH TROPICAL MSTR
TO CONT TO STREAM NWD...PRBLY IN A CONCENTRATED BAND/ZONE AS
SUGGESTED BY ALL SYNOPTIC AND MESOSCALE GNDC. THE AREA WL LKLY
SHIFT EWD FM CURRENT ORIENTATION BLURDG-PTMC HIGLANDS TO SOMETHING
CLSR TO THE I-95 CORRIDOR. A DRY SLOT MAY WORK INTO THE MTNS...
ALSO ITS YET TO BE SEEN IF IT/LL MAKE IT THIS SIDE OF THE APLCHNS.
PWAT STILL 2.0-2.5 INCHES...MEANING WHERE IT RAINS...RATES WL BE
VERY EFFICIENT. PLUS...FFG LOW AFTER RECENT RAINS...AND AXIS WL BE
APPROACHING AREA WHICH RECEIVED RAFL FM IRENE. HV XTNDD FFA THRU
TNGT.
THE OTR CONSIDERATION TAFTN WL BE THE SVR THREAT. WHILE LLVLS
REMAIN STBL W/ A PRETTY DECENT INVSN...THAT INVSN SHUD ERODE W/
DAYTIME HEATING AS THE HUMID /70F DEWPT/ AMS WORKS INLAND IN ADVC
OF WMFNT...WHICH WL BE LIFTING NWD W/ THE LOW. SO WE/LL BE DEALING
W/ A WARM/HUMID AMS W/ GOOD INSTBY AND SUFFICIENT HELICITY.
THEREFORE WE/RE SUSCEPTIBLE TO A WIND/ISOL TORNADO THREAT. ALREADY
CARRYING THAT RISK IN THE HWO. HV OPTED NOT TO INCL IN GRIDS ATTM. THE
TRICKY PART IS FIGURING OUT HOW FAR W TO BRING THE HUMIDITY/INSTBY...
AS SVR WX WL ONLY RESIDE W/IN THAT ZN.
THE WMFNT...AND THE THREAT OF TSRA...WL PASS N OF AREABY ELY EVNG.
ALSO SINCE THE EFFECTS OF DAYTIME HEATING WL WANE...HV ENDED TSTM
MNTN IN GRIDS SOON AFDK. HWVR...STILL HV A CHANNEL OF VERY MOIST
AIR IN THE ERN CWFA OVNGT...AND AM CARRYING CAT POPS ERN WV PANHANDLE
TO THE NRN PIEDMONT EWD TO THE BAY OVNGT.
GIVEN ANTICIPATED CLDCVR...DID NOT GO AS WARM AS MAV MAXT. THAT
SAID...XPCT A TEMP SPIKE TO COINCIDE W/ WWD MSTR /HIER DEWPT/
ADVCTN. THINK THE TRUTH WL RESIDE BTWN MAV/MET MOS...BUT RECOGNIZE
THAT ANY INSOALTION WUD EASILY MAKE MAV NUMBERS REACHABLE. FOR A
SIMILAR REASONAING...STUCK W/ HIER MET MOS MIN-T.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
BOTH THE SFC AND UPPER LOWS WL REMAIN OVER THE OHIO VALLEY THU-FRI.
THEREFORE...THE CWFA WILL REMAIN IN A RELATIVELY HIGH PRECIPITABLE
WATER ENVIRONMENT. IT LOOKS AS IF AN AXIS OF CONVERGENCE WILL
REMAIN OVER THE CWA AS WELL...NOT TO MENTION SHORTWAVES EJECTED
FROM THE BASE OF THE UPPER LOW. RESULT WILL BE A CONTINUATION OF
UNSETTLED CONDITIONS ACROSS THE CWA. POPS REMAIN ABOVE CLIMATOLOGY
AND WITH THE GROUND ALREADY SATURATED AT THAT POINT ANY ADDITIONAL
RAINFALL MAY PROMOTE/EXACERBATE FLOODING PROBLEMS.
GIVEN CLOUDS/UNSETTLED CONDITIONS...CONTINUED TO FORECAST HIGH
TEMPERATURES THURSDAY/FRIDAY BELOW MOS VALUES AND NEAR MOS VALUES
AT NIGHT.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
GUIDANCE SHOWS A STAGNANT PATTERN CONTINUING INTO THE WEEKEND. WHAT
REMAINS OF TROPICAL STORM LEE WILL RETROGRADE SLIGHTLY FROM ITS
LOCATION OVER EASTERN TENNESSEE TO PERSIST AS A STACKED UPPER LEVEL
LOW OVER THE CENTRAL CONUS. THIS WILL ASSIST IN FUNNELING MOISTURE
FROM THE GULF INTO THE CWA THROUGH THE WEEKEND. DUE TO THE ABUNDANT
MOISTURE AVAILABLE...SHOWERS AND THUNDERSTORMS ARE POSSIBLE EACH
DAY. MODERATE DAYTIME HIGHS IN THE LOW 80S WITH OVERNIGHT LOWS IN
THE LOW TO MID 60S ARE EXPECTED EACH DAY. THE LATEST TRACK FROM THE
HURRICANE CENTER FOR KATIA SHOWS THE CENTER MOVING ABOUT 450 MILES
TO THE EAST OF THE DELMARVA COAST. FLOW AROUND KATIA WILL ALSO
ASSIST IN CHANNELING MOISTURE RICH AIR INTO THE CWA FOR FRIDAY AND
SATURDAY.
SUNDAY LOOKS TO START A POSSIBLE DRYING TREND FOR THE EXTENDED
PERIOD. THE STACKED LOW OVER THE CONUS WILL BEGIN TO DRIFT OFF THE
ATLANTIC THROUGH THE BEGINNING OF THE WEEKEND TRANSITIONING
PREVAILING MID AND UPPER LEVEL FLOW FROM SOUTHWEST TO NORTHWEST.
RIGHT NOW...MONDAY LOOKS TO HAVE JUST A SLIGHT CHANCE FOR PRECIP.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
SHRA HV GNLY LIFTED N OF TERMINALS...BUT IFR CIGS REMAIN. VSBY
THRU THE ELY MRNG WL BE SPOTTY BTWN MVFR/VRB AND IFT...BASED ON SHRA
CVRG. REGARDLESS...FLGT RESTRICTIONS FOR THE MRNG PUSH.
LKLY TO GET LIFTING CIGS DURING THE DAY...BUT WL HV PLENTY OF SHRA
TOO...AND PERHAPS A FEW TSRA. THAT MAKES TAFS CHALLENGING...AS
CONDS WL BE BOUNCING ARND. LTST FCST MARKS AN IMPVMT TO MVFR FOR
THE AFTN...RECOGNIZING THAT ANY TSRA WL BRING ADDTL RESTRICTIONS.
AT THIS POINT CANNOT PINPOINT WHEN/WHERE HVR RA/TSRA WL BE. THE
CURRENT NNELY FLOW SHUD BECOME SELY BHD WMFNT.
EXPECT CONDITIONS TO DEGRADE BACK TO IFR FOR WEDNESDAY NIGHT AS
EASTERLY FLOW CONTINUES. MVFR-IFR RESTRICTIONS MAY PERSIST INTO
THE END OF THE WEEK DURING THE NIGHTTIME AND MORNINGS WITH
RELATIVE IMPROVEMENTS EACH AFTERNOON.
VISIBILITY REDUCTIONS AS WELL AS LOW CEILINGS DUE TO CONTINUING
SHOWERS WILL BE POSSIBLE ACROSS ALL TERMINALS THROUGH THE
BEGINNING OF THE WEEKEND. CONDITIONS COULD BEGIN TO IMPROVE SUNDAY
AS THE CLOSED UPPER LEVEL LOW OVER THE CONUS BEGINS TO DRIFT OFF
THE ATLANTIC COAST.
&&
.MARINE...
MAROBS ATTM ALL BLO SCA...AND GDNC GNLY SUGGESTING IT/LL STAY THAT
WAY AS HIER WNDS PRESENTLY TRAPPED ABV INVSN. A WWD MVG WMFNT WL
CASE NNELY WNDS TO VEER SELY. THE MIXING PROFILE ACRS WATERS
DURING THE DAYTIME HRS SHUD BE POOR. BUT...SHOWERS AND SCATTERED
THUNDERSTORMS WILL PRODUCE LOCALLY HEAVY RAINFALL THAT CAN REDUCE
VSBYS. HV OPTED TO CANX SCA AS ANY HIER WNDS SHUD BE ASSOC W/
TSRA...IN WHICH CASE SMW/S WUD BE REQD.
EAST/SOUTHEAST WINDS WL CONTINUE WEDNESDAY NIGHT THROUGH FRIDAY.
SHRA AND ISOLATED THUNDERSTORMS WILL RESULT IN LOCAL VISIBILITY
RESTRICTIONS.
THE PRIMARY MARINE CONCERNS FOR THE EXTENDED PERIOD ARE VISIBILITY
REDUCTIONS DUE TO SHOWERS AND THUNDERSTORMS. THE UPPER LEVEL PATTERN
WILL BEGIN TO TRANSITION AT THE END OF THE WEEKEND CAUSING DECLINING
PRECIPITATION CHANCES FOR THE BEGINNING OF THE WORK WEEK.
&&
.HYDROLOGY...
HERE ARE SOME OF THE LATEST RVR STAGE FCSTS BASED ON RAINFALL FCSTS:
PTMC RVR MODERATE STAGE FCST
PAW PAW 28 FT 29.0 FT THU EVE
HANCOCK 33 FT 29.2 FT THU EVE
WILLIAMSPORT 25 FT 24.0 FT THU EVE
PT OF ROCKS 20 FT 29.3 FT FRI AFTN
SHENANDOAH RVR FLOOD STAGE FCST
MILLVILLE 13.5 FT 13.8 FRI MORN
THE LATEST FORECAST CALLS FOR MAJOR FLOODING ALONG THE POTOMAC RIVER
AT SHEPHERDSTOWN...POINT OF ROCKS...AND LITTLE FALLS. MAJOR FLOODING
IS ALSO PROJECTED ON CONOCOCHEAGUE CREEK.
THESE WL OBVIOUSLY BE UPDATED SVRL TIMES IN THE COMING
DAYS. ALL W/ INTERESTS ON THESE RVRS SHOULD BEGIN TAKING
PRECAUTIONS. RIVER FLOOD WATCHES ARE IN EFFECT FOR LOCATIONS ALONG
THE POTOMAC RIVER BASIN. IN ADDITION...RIVER FLOOD WARNINGS HAVE
BEEN ISSUED FOR SENECA CREEK...CONOCOCHEAGUE CREEK...AND OPEQUON
CREEK. A RIVER FLOOD WARNING IS ALSO IN EFFECT FOR THE POTOMAC RIVER
AT PAW PAW.
A FLASH FLOOD WATCH HAS NOW BEEN EXTENDED UNTIL MIDNIGHT TNGT.
WIDESPREAD ONE TO THREE INCHES RAINFALL IS EXPECT THROUGH THIS
EVENING...WITH ISOLATED AMOUNTS OVER 5 INCHES. HEAVIEST RAINFALL
AMOUNTS TODAY AND TONIGHT ARE LIKELY TO BE ALONG AND EAST OF THE
BLUE RIDGE. THE FLASH FLOOD WATCH MAY NEED TO BE EXTENDED INTO
THURSDAY AS HVY RN MAY CONTINUE. THE THREAT FOR HEAVY RAIN WILL
PERSIST INTO FRIDAY AS WELL.
&&
.TIDES/COASTAL FLOODING...
WATER LEVELS NEAR NRML ERY THIS MRNG ACRS TIDAL POTOMAC AND WRN
SHORE OF MD CHESAPEAKE BAY. HWVR...XPCT SELY FLOW TO DVLP AND INCR
DURG THE DAY TDA...WHICH COMBINED WITH PERSISTENT LOPRES WILL
CAUSE POSITIVE ANOMALIES TO DVLP. WATER LEVELS SHUD STAY WITHIN
ONE FOOT OF NRML THRU THE EVE HIGH TIDE...PRECLUDING MINOR COASTAL
FLOODING. TNGTS HIGH TIDE WILL LIKELY COINCIDE WITH POSITIVE
ANOMALIES OF NEAR 2 FT...AND THIS WILL CREATE AT LEAST MINOR
INUNDATION. THREAT FOR MDT FLOODING EXISTS...AND COASTAL FLOOD
WATCH IN EFFECT TNGT THRU THU NGT. FRESHWATER RUNOFF WILL LEAD TO
SIGNIFICANT RISES UPSTREAM OF TIDAL POTOMAC...WHICH MAY CAUSE
ADDITIONAL FLOODING PROBLEMS BY AS EARLY AS LATE TMW.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...FLASH FLOOD WATCH THROUGH THIS EVENING FOR DCZ001.
COASTAL FLOOD WATCH FROM THIS EVENING THROUGH FRIDAY MORNING
FOR DCZ001.
MD...FLASH FLOOD WATCH THROUGH THIS EVENING FOR MDZ003>007-009>011-
013-014-016>018-501-502.
COASTAL FLOOD WATCH FROM THIS EVENING THROUGH FRIDAY MORNING
FOR MDZ007-011-013-014-016>018.
VA...FLASH FLOOD WATCH THROUGH THIS EVENING FOR VAZ025>031-036>040-
042-050>057-501>504.
COASTAL FLOOD WATCH FROM THIS EVENING THROUGH FRIDAY MORNING
FOR VAZ052>055-057.
WV...FLASH FLOOD WATCH THROUGH THIS EVENING FOR WVZ050>053-055-
501>506.
MARINE...NONE.
&&
SYNOPSIS...HTS/LARSEN
NEAR TERM...HTS
SHORT TERM...HTS/PELOQUIN
LONG TERM...LARSEN
AVIATION...HTS/PELOQUIN/LARSEN
MARINE...HTS/PELOQUIN/LARSEN
HYDROLOGY...SBK
TIDES/COASTAL FLOODING...SBKHAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 531 AM EDT WED SEP 7 2011 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 081000- 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- 531 AM EDT WED SEP 7 2011 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...TODAY AND TONIGHT A FLASH FLOOD WATCH REMAINS IN EFFECT FOR THE ENTIRE AREA THROUGH THIS EVENING. PLEASE REFER TO THE LATEST HAZARD MESSAGE /FFALWX/ FOR FURTHER DETAILS. SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING. LOCALLY DAMAGING WIND GUSTS AND ISOLATED TORNADOES WILL BE POSSIBLE. A PERSISTENT ONSHORE FLOW WILL DEVELOP TODAY AND LIKELY RESULT IN MINOR COASTAL FLOODING NEAR TIMES OF HIGH TIDE. THERE IS ALSO THE POTENTIAL FOR MODERATE COASTAL FLOODING TONIGHT. A COASTAL FLOOD WATCH REMAINS IN EFFECT. RIVER FLOOD WARNINGS ARE IN EFFECT FOR CONOCOCHEAGUE AND OPEQUON CREEKS AS WELL AS THE POTOMAC RIVER AT PAW PAW. SEE FLOOD WARNINGS /WBCFLWLWX/ FOR DETAILS. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THE THREAT FOR HEAVY RAIN WILL PERSIST THROUGH AT LEAST THURSDAY... WITH A CONTINUED RISK OF FLASH FLOODING. THE POTENTIAL FOR MODERATE COASTAL FLOODING CONTINUES THURSDAY INTO FRIDAY. A COASTAL FLOOD WATCH REMAINS IN EFFECT. RIVER FLOODING...SOME OF IT MAJOR...IS EXPECTED ALTHOUGH THE POTOMAC RIVER THURSDAY AND FRIDAY...INCLUDING THE POTOMAC RIVER AT LITTLE FALLS. A RIVER FLOOD WATCH IS IN EFFECT FOR THIS PERIOD. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS ON WEDNESDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING. PLEASE RELAY REPORTS OF FLOODING AND HEAVY RAINFALL TOTALS TO THE NATIONAL WEATHER SERVICE. MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504- WVZ050>053-055-501>506-081000- 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- 531 AM EDT WED SEP 7 2011 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...TODAY AND TONIGHT A FLASH FLOOD WATCH IS IN EFFECT FOR THE ENTIRE AREA THROUGH THIS EVENING. PLEASE REFER TO THE LATEST HAZARD MESSAGE /FFALWX/ FOR FURTHER DETAILS. RIVER FLOOD WARNINGS ARE IN EFFECT FOR THE POTOMAC RIVER AT PAW PAW...AND THE OPEQUON AND CONOCOCHEAGUE CREEKS. SEE PRODUCT /WBCFLWLWX/ FOR DETAILS. SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EVENING. LOCALLY DAMAGING WIND GUSTS AND ISOLATED TORNADOES WILL BE POSSIBLE...ROUGHLY EAST OF A HAGERSTOWN TO ORANGE LINE. .DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY THE THREAT FOR HEAVY RAIN WILL PERSIST THROUGH AT LEAST THURSDAY... WITH A CONTINUED RISK OF FLASH FLOODING. RIVER FLOOD WARNINGS CONTINUE INTO THURSDAY FOR SOME LOCATIONS...AND RIVER FLOOD WATCHES ARE IN EFFECT FOR MUCH OF THE POTOMAC RIVER AS WELL AS THE MONOCACY RIVER AT FREDERICK. MINOR TO MODERATE RIVER FLOODING IS FORECAST INTO FRIDAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING. PLEASE RELAY REPORTS OF FLOODING AND HEAVY RAINFALL TOTALS TO THE NATIONAL WEATHER SERVICE. HTS/SBK
The Sterling radar (KLWX), 81 km away, was scanning. The volume nearest the first event began at 14:20 UTC.
61 flash flood, 8 flood. Local standard time, as filed.
The ramp from Route 295 northbound to Interstate 95 was closed due to flash flooding. A nearby rain gauge measured 4.33 inches.
All westbound lanes of Route 40 west of Saint Johns Lane were closed due to flash flooding. A rain gauge near the event totalled 10.29 inches.
A portion of the outer loop of the Capital Beltway was flooded near Exit 19. A nearby rain gauge measured 4.76 inches.
Route 40 was closed at Normandy due to flash flooding. A nearby spotter observed 8.49 inches of rain.
Route 1 is closed at Patuxent Ridge due to flash flood. A trained spotter measured 7.93 inches of rain near this event.
Intersection of Roosevelt and Meadowridge Roads closed due to flash flooding. A nearby rain gauge reported 7.70 inches.
Stevens Forest Road was closed near Broken Land due to flash flooding. A rain gauge recorded 6.54 inches.
Route 108 was closed near Thunder Hill due to flash flooding. A nearby rain gauge measured 6.78 inches.
State Route 122 ramps were closed at Interstate 695 due to flash flooding. A nearby rain gauge totalled 7.87 inches.
Route 1 was completely closed at Ritz Way. A nearby rain gauge measured 7.09 inches.
The turn lane on Route 5 onto Surratts Road was closed due to flash flooding. A nearby rain gauge recorded 4.57 inches.
Three inches of water were flowing across Frederick Avenue at its intersection with Rolling and Overbrook Roads. A rain gauge in the vicinity measured 7.67 inches.
Beach Drive was closed due to flash flooding. A nearby spotter observed 8.50 inches of rain.
Portions of Main Street in Ellicott City was evacuated due to high water. A spotter nearby measured 6.33 inches of rain.
Valley Mede neighbor was evacuated due to high water. A nearby spotter recorded a storm total of 6.20 inches near the time of this event.
Route 50 Westbound was closed at Davidsonville Road due to flash flooding. A rain gauge near the event received a total of 7 inches.
Route 244 was closed due to flash flooding at Abell Creek. A spotter near the event observed 4.5 inches of rain.
Frederick road leading into the east side of Ellicott City is closed due to flash flooding. Water was at a depth above the bumpers of cars. A nearby spotter observed 9.40 inches of rain for a storm total.
Route 225 was flooded and closed near Route 224. A nearby rain gauge tallied 6.13 inches.
Route 648 was flooded and closed between Lake Front Drive and Nursery Road. Storm total precipitation at Baltimore-Washington International Airport, nearby, was 7.97 inches.
Route 1 was closed in both directions at Assateague Drive. A nearby rain gauge tallied 5.24 inches during the day.
Maryland Route 725 was flooded and closed at John Rogers Boulevard due to floodwaters at the confluence of Western Branch and Collington Branch. A nearby rain gauge reportedly measured 4.58 inches.
The intersection of Slade Avenue and Park Heights Avenue was closed at the Baltimore County and Baltimore City border. A nearby rain gauge had 7.21 inches in it.
Route 45 was closed at Beaver Run Lane due to flash flooding. The nearest rain gauge to the event measured 10.09 inches.
High water was blocking the northbound lanes of Route 29 between Routes 32 and 175. A spotter in Columbia measured 5.18 inches of rain.
High water was blocking lanes of the Route 50, 201, and 295 interchange. A nearby spotter observed 4.64 inches of rain.
Numerous roadways were closed due to flash flooding in Waldorf and across Charles County. A spotter in Waldorf measured 8.71 inches of rain.
The intersection of Houkes Mill and Turner roads was closed due to flash floodin. A nearby rain gauge recorded 3.84 inches.
Route 140 was closed at Kenmar Avenue due to flash flooding. A rain gauge near the event tallied 5.74 inches.
Route 450 was closed at Saint Stephens Church Road due to flash flooding. A nearby rain gauge at 6.76 inches.
Route 103 was closed at Roosevelt Boulevard due to flash flooding.
Mattaponi Creek flash flood forced the closure of Croom Road at Mattaponi Road. The spotter that observed the event recorded 6.20 inches.
Route 198 was closed at the Baltimore-Washington Parkway. A rain gauge near the event recorded 5.98 inches.
Route 257 was flooded and closed at Banks O Dee Road. A nearby spotter observed 4.52 inches of rain.
Route 145 was closed at Ashland Road due to flash flooding. A nearby rain gauge tallied 6.64 inches.
The Little Patuxent River at Volmerhausen Road topped the bridge and flooded it.
Water Street was closed north of Route 4 due to flooding. A nearby rain gauge totalled 4.63 inches.
Route 165 was closed due to flash flooding near Route 24. A nearby rain gauge recorded 3.85 inches.
Paper Mill Road was closed at Poplar Hill Road due to flash flooding. Rainfall in the area was measured at 4.80 inches.
Route 7 was closed from Route 136 to Route 543 due to flash flooding. Rainfall near the event was measured at 3.12 inches.
A 49 year old male drowned in floodwaters of the Magothy River on Riverside Drive.
Route 301 was closed at Route 6 due to flash flooding. A nearby rain gauge tallied a storm total of 7.83 inches.
Route 301 was closed at Chapel Point Road due to flash flooding. A rain gauge in the area recorded 6.91 inches.
Route 227 West was closed at Ray Drive due to flash flooding. A nearby spotter reported 5.84 inches of rain.
Port Tobacco Road was closed between Rose Hill and Valley Roads.
Route 4 at Woodyard Road was closed due to flash flooding. A nearby rain gauge tallied 6.72 inches.
Multiple roadways were closed in and around Bowie due to flash flooding. A nearby rain gauge totalled 4.53 inches.
Route 97 was closed due to flash flooding on Big Silver Run. A spotter near this event recorded 8.07 inches of rain.
Goshen Road was closed between East Village and Warbuild Road due to flash flooding. Storm total precipitation from near this event was 3.09 inches, according to rain gauge measurement.
Numerous high water rescues were ongoing across Waldorf and surrounding areas.
Intersection of Liberty Parkway and Dunman Way was closed due to flash flooding. A nearby rain gauge measured 4.60 inches.
North Point Road was closed at German Hill Road due to flash flooding.
Meritt Boulevard at Rabon Avenue was closed due to flash flooding.
Route 214 was closed near Beards Point Road due to flash flooding. A nearby rain gauge had a measurement of 5.30 inches.
Chesapeake Avenue was closed between 3rd and 4th Streets due to flash flooding. A nearby spotter measured 4.68 inches of rain.
Route 261 was closed at Summer City Boulevard due to flash flooding. A rain gauge near the event observed 4.67 inches.
Flash flooding caused landslide on Saint Paul Street. A tree was downed and landslide affected automobiles in the area.
Route 176 was closed between Route 648 and Central Avenue due to flooding. A nearby rain gauge had a measurement of 5.16 inches.
Fishers Station Road was closed due to flooding at Route 4.
Route 202 was closed at White House Road due to flash flooding. A rainfall amount of 4.30 inches was reported near the event.
Route 1 southbound was flooded and closed at Priestford Road. A nearby spotter observed 2.92 inches of rain.
Route 80 was flooded and closed west of Ed McClain Road.
Routes 108 and 109 near Damascus were closed due to flash flooding. A nearby rain gauge tallied 3.10 inches.
Kings Valley Road closed and under 2 feet of flowing water.
Muddy Branch Road closed due to flash flooding.
Flash flooding caused structural damage on the bridge over Dry Seneca Creek on Montevideo Road.
Port Tobacco Road was closed at Wards Run due to flash flooding.
Many roads were closed throughout the county due to flash flooding. A number of sinkholes were also reported.
Route 190 was closed between Violetters Lock Road and Manor Stone Drive.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Flood, Anne Arundel | 2011-09-07 | 49 | Male | Outside/Open Areas | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2011Every state in 2011This day in weather historyWarnings in Maryland, September 2011
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: 346625, 346628, 346635, 346638, 346640, 346641, 346642, 346643, 346644, 346646, 346647, 346733, 346648, 346735, 346736, 346738, 346739, 346740, 346741, 346742, 346744, 346746, 346748, 346750, 346751, 346753, 346755, 346757, 346756, 346758, 346761, 346762, 346765, 346764, 346766, 346767, 346769, 346770, 346771, 346772, and more.