Slow moving showers passed across northeast Maryland. With saturated ground in place, heavy downpours were enough to produce an isolated flash flood in Harford County.
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.
Slow moving showers passed across northeast Maryland. With saturated ground in place, heavy downpours were enough to produce an isolated flash flood in Harford County. An observer in Bel Air recorded 1.45 inches of rain.
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 19, 7:10 PM EST, 20 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
810 PM EDT MON SEP 19 2011
.SYNOPSIS...
SOUTHERLY FLOW WILL DEVELOP ACROSS THE AREA TONIGHT AS HIGH
PRESSURE MOVES EASTWARD OFF THE MID-ATLANTIC COAST. AN UPPER-LEVEL
DISTURBANCE WILL CROSS THE REGION TUESDAY. MOIST SOUTHERLY FLOW
IS EXPECTED THROUGH THE REST OF THE WEEK...WITH INCREASING CHANCES
FOR PRECIPITATION. A COLD FRONT MAY ARRIVE BY SATURDAY.
&&
.NEAR TERM /THROUGH TUESDAY/...
NO SGFNT CHGS MADE TO FCST. ONLY ADJUSTMENT WAS TO TIMING OF PCPN
ONSET E OF MTNS GIVEN RECENT RADAR TRENDS. FCST STILL CALLS FOR
INCRG CVRG OF SHWRS LATE TNGT. TSTM PSBLTYS WILL HINGE ON CLD
BREAKS DURG THE AFTN. MODELS SUGGEST BEST CHC FOR SUCH BREAKS WILL
BE ACRS SRN ZONES. PREV DISCUSSION FOLLOWS...
LOW PRESSURE OFF THE NEW ENGLAND COAST WILL DEVELOP AS IT MOVES
NORTHEAST...ALLOWING SFC HIGH PRESSURE TO MOVE OFF THE NRN MID
ATLANTIC COAST THIS EVENING. ELY FLOW ACROSS THE CENTRAL MID
ATLANTIC WILL VEER SELY THEN SLY TONIGHT. AN UPR TROUGH ASSOCIATED
WITH A LOW OVER NRN ONTARIO AND CURRENTLY STRETCHING DOWN THE
MIDWEST...WILL WEAKEN AS IT ENTERS THE ERN CONUS TONIGHT.
NUMEROUS SHOWERS ACROSS NRN WV TO GRAZE THE POTOMAC HIGHLANDS THIS
AFTERNOON...THEN THE MAIN SLUG OF MOISTURE AND ASSOCIATED RAIN
SPREADS EAST...MAINLY ACROSS THE NWRN HALF OF THE CWA TONIGHT.
CATEGORICAL POPS WEST OF THE SHEN VLY THROUGH MIDNIGHT...THEN UP
ALONG THE MASON-DIXON LINE LATE TONIGHT.
DROPPED TEMPS A BIT GIVEN LACK OF INSOLATION THIS AFTERNOON...UPR
60S MAX TEMPS...MIN TEMPS TONIGHT UPR 50S.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH 6 PM TUESDAY/...
FIRST FULL DAY OF SLY FLOW THIS WEEK. LOW TO MID 60F DEWPOINTS
SURGE INTO THE AREA. ONGOING SHOWERS ASSOCIATED WITH THE UPR
TROUGH IN THE MORNING...PARTICULARLY NORTH. MID AND UPR LEVELS DRY
OUT IN THE AFTERNOON...ALLOWING BREAKS IN THE OVC /WENT MOSTLY
CLOUDY/ AND LOW CAPE /UP TO 500 J/KG/. CHANCE SHOWERS/ISOLATED
THUNDERSTORMS ACROSS THE CWA...BEST CHANCES BLUE RIDGE AND WEST
WHERE CLOUD BREAKS OCCUR FIRST. MAX TEMPS MID TO UPR 70S.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
NEXT SVRL DAYS LOOK LK THERE'LL BE A LOT OF CLD CVR. ONE NOTABLE
EFFECT OF THIS WL BE LTL TEMP VARIATION THRU THE END OF THE WORK
WK - HIGHS IN THE U70S/A80 XCPT L70S IN THE HIGHLANDS...LOWS IN
THE 50S W OF THE BLUE RIDGE/60S E W/ WARMEST TEMPS ALONG THE CHES
BAY.
AREA UNDER THE EFFECTS OF CAD ATTM. APRCHG TROF WL ADD TO THE LO
LVL MOISTURE KEEPING THE RGN M CLDY. QSTN WL BE IF/HOW MUCH PCPN
CAN BE REALIZED IN THIS ENVIRONMENT? BEST CHCS WL WED NGT THRU FRI W/
UPPER LOW OVR WRN QUEBEC..LONG WV TROF XTNDG THRU MN/IA...AND A
COLD FNT/SHORT WV JUST W OF THE APLCHNS. THE FNT WL BE SLOW TO
MOVE THRU THE MID ATLC KEEPING AREA IN CHCS OF RW/ISOLD TSTMS. AS
CAN BE SEEN ON OUR WEB PAGE E OF THE MTNS...ESEPCIALLY IN THE I-95
CORRIDOR...HAS XPRNCD SOME TREMENDOUS AMTS OF RAFL IN THE PAST FEW
WEEKS. AND WHILE THIS WL ADD TO THE TOTAL AT THIS TIME NOT
THINKING ABT FLDG. WE'LL KEEP AN EYE ON THIS IN THE COMING DAYS.
SOME VARIANCE IN THE XTND MDLS OVR THE WKND W/ GFS SHOWING A MOVE
VIGOROUS UPR LOW OVR MI/IN. ONE THING LOOKS CERTAIN IS WE WON'T
EXPRNC ANY WIDE TEMP SWINGS IN THE MID ALTC - HIGHS IN THE
M70S/LOWS IN THE M50S AND L60S. THERE IS MORE UNCERTAINTY
REGARDING POPS FOR THE WKND.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
MVFR CIGS XPCD TO DVLP TNGT AS SHWRS SPREAD EWD ACRS MTNS. UNTIL
PCPN ARRIVES...VFR-MVFR FOG PSBL AS CIGS LWR SLOWLY. GUIDANCE
SUGGESTS PSBLTY OF IFR CIGS LATE TNGT AND EARLY TMW...BUT FCST
DOES NOT REFLECT THIS SCENARIO ATTM OWING TO VERY LOW CONFIDENCE.
IN WAKE OF MRNG PCPN...CIGS MAY INCR TO VFR.
AREA WL RMN UNDER XTNSV CLD CVR THRU THE END OF THE WK W/ CHCS OF
RW/TRW WED NGT-FRI. AT THIS TIME UNSURE THAT THERE WL BE
SIG LIMITATIONS OF CIG/VSBY. LATER SHIFTS CAN HONE IN ON THIS
FURTHER.
&&
.MARINE...
LGT WINDS XPCD FOR THE WATERS AMID VACATING SFC HIPRES. PCPN WILL
SPREAD E OF MTNS LATE TNGT AND TMW MRNG AND COULD IMPACT THE
WATERS. DP CNVCTN NOT XPCD ATTM...SO NO HAZARDS ANTICIPATED.
MUCH CLD CVR OVR THE WATERS IN THE COMING DAYS W/ CHC OF RW/ISOLD
TRW...ESPECIALLY WED NGT THRU FRI. WL KEEP WINDS BLO SCA LVLS.
&&
.TIDES/COASTAL FLOODING...
ELY FLOW HAS BCM SELY OVER THE WATERS...WHICH WILL SUPPORT CONTD
POSITIVE TIDAL ANOMALIES...WHICH RECENTLY WERE NOTED TO BE 1.0-1.5
FT ABV NRML. GIVEN THESE ANOMALIES AND FCSTD WATER LVLS...MINOR
FLOOD THRESHOLDS SHOULD BE EXCEEDED EASILY DURG THE OVNGT HIGH
TIDE. COASTAL FLOOD ADZY HAS BEEN CONTD.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...COASTAL FLOOD ADVISORY UNTIL 5 AM EDT TUESDAY FOR DCZ001.
MD...COASTAL FLOOD ADVISORY UNTIL 5 AM EDT TUESDAY FOR MDZ007-011-
013-014-016>018.
VA...COASTAL FLOOD ADVISORY UNTIL 5 AM EDT TUESDAY FOR VAZ052>055-
057.
WV...NONE.
MARINE...NONE.
&&
UPDATE...KRAMAR
PREV DISCUSSION...JACKSON/WOODY!HAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 603 PM EDT MON SEP 19 2011 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 201000- 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- 603 PM EDT MON SEP 19 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...TONIGHT A COASTAL FLOOD ADVISORY IS IN EFFECT THROUGH LATE TONIGHT ALONG THE TIDAL POTOMAC RIVER AND THE WESTERN SHORE OF THE MARYLAND CHESAPEAKE BAY. REFER TO THE LATEST HAZARD MESSAGE /CFWLWX/ FOR DETAILS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY SOUTHERLY FLOW WILL PROLONG THE THREAT OF MINOR COASTAL FLOODING THROUGH FRIDAY ALONG THE TIDAL POTOMAC RIVER AND THE WESTERN SHORE OF THE MARYLAND CHESAPEAKE BAY. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504- WVZ050>053-055-501>506-201000- 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- 603 PM EDT MON SEP 19 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...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. KRAMAR
The Sterling radar (KLWX), 110 km away, was scanning. The volume nearest the first event began at 00:31 UTC.
1 flash flood. Local standard time, as filed.
High water over the road in a few spots around Route 23 and Salem Church Road. An observer nearby recorded 1.12 inches of rain.
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: 347120.