Early in the last week of September, a rich plume of tropical moisture, originating from the western Caribbean Sea, spread northward along the east coast of the United States. As this moisture interacted with a stationary boundary across Virginia, widespread moderate to heavy rain fell across the Mid-Atlantic September 27.
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.
Early in the last week of September, a rich plume of tropical moisture, originating from the western Caribbean Sea, spread northward along the east coast of the United States. As this moisture interacted with a stationary boundary across Virginia, widespread moderate to heavy rain fell across the Mid-Atlantic September 27. Rainfall amounts of 2 to 4 inches caused minor isolated flash flooding in Montgomery County, Maryland.
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 27, 10:22 AM EST, 1 hour 59 minutes earlier.
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1122 AM EDT MON SEP 27 2010
.SYNOPSIS...
LOW PRESSURE OVER GEORGIA WILL MOVE NORTHWARD ALONG THE APPALACHIANS
TODAY AND INTO THE EASTERN GREAT LAKES TUESDAY. DEEP MOISTURE WILL
BE DRAWN INTO THIS SYSTEM...BRINGING A SOAKING RAIN TO THE REGION
TONIGHT THROUGH TUESDAY. HIGH PRESSURE WILL BUILD INTO THE AREA
WEDNESDAY. A COLD FRONT WILL MOVE THROUGH THE REGION
FRIDAY...FOLLOWED BY A RETURN TO HIGH PRESSURE FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
A RAPIDLY CHANGING WEATHER SITUATION OVER THE PAST SEVERAL HRS.
THE LOW PRESSURE SYSTEM RESPONSIBLE IS STILL WELL TO THE
SOUTH...BUT ITS EFFECTS ALREADY BEING NOTICED ACROSS THE EASTERN
SEABOARD. AN UPPER LOW THAT INITIALLY BEGAN AS A CUT-OFF WAVE OVER
THE NRN PLAINS HAS WRAPPED UP DOWN ACROSS THE DEEP SOUTH...AND HAS
TAPPED COPIOUS AMOUNTS OF GULF MOISTURE - SPREADING IT FROM THE
GULF COAST TO NEW ENGLAND.
NEARLY 2 INCHES OF RAIN HAS FALLEN ACROSS THE SWRN TIER OF THE CWA
/LOCALIZED AREAS OF NELSON-ALBEMARLE/. THE REST OF THE AREA HAS
RECEIVED ONLY A COUPLE TENTHS OF AN INCH ON AVERAGE. A FLOOD WATCH
IS IN EFFECT FROM LATE THIS EVENING INTO THE OVERNIGHT HRS. THE
AREA BEING UNDER VARIOUS LEVELS OF DROUGHT HAVE HIGH FFG VALUES.
THESE AREAS WOULD NEED A COUPLE MORE INCHES OF RAIN TO BEGIN TO
OVERCOME THE DEFICIT IN TERMS OF FFG...BUT THE ACTIVITY APPROACHING
FROM THE GULF IS FAIRLY TROPICAL IN NATURE SO EVEN MINOR ACTIVITY
ON RADAR WOULD POTENTIALLY PRODUCE HIGH RAINFALL RATES /ESPECIALLY
THE LATE NIGHT ACTIVITY EXPECTED/.
PLENTY OF LOW LEVEL SHEAR ON THE WAY FROM THE SOUTH AS
WELL...SHORT TERM GUIDANCE GIVING A CLEAR SIGNAL THAT THESE LOW
LEVEL JET MAXES WILL INCREASE IN STRENGTH OVER TIME AS THE LOW
NEARS THE MID ATLC OVER THE NEXT 12-24 HRS. HELICITY VALUES WILL
INCREASE...SHEAR WILL BE IMPRESSIVE AND LOCALIZED SMALL-SCALE
VORTICES ARE EXPECTED TO APPEAR IN WEAK/MODERATE CONVECTION THAT
DEVELOPS DURING THIS TIME PERIOD. EVEN A FEW OF THE CURRENT
SHOWERS AFFECTING THE I-95 CORRIDOR HAVE INDICATIONS OF WEAK LOW
LEVEL ROTATION.
MORE CLOUDS AND PRECIP FOR THE REMAINDER OF THE DAY...AND
INCREASED ACTIVITY LATER THIS EVE AND TONIGHT. HIGHS WILL ONLY
REACH THE L-M70S AND STAY VERY MOIST THIS AFTN.
&&
.SHORT TERM /TUESDAY/...
TNGT LOOKS TO BE ACTIVE AS WELL. HV ISSUED A FLASH FLD WATCH FOR
TNGT FM NELSON-HIGHLAND-PENDLETON-GREENE. THE RAFL OF TDA WL PRIME
THE RGN FOR TNGT. FFG VALUES ARE 4.5" IN 3 HR...WHICH CERTAINLY IS
A LARGE NUMBER...BUT I'VE SEEN THIS ENOUGH TO KNOW THAT FLDG CAN
BE INITIATED W/ LESSER AMTS. BLV THAT A PD OF FAIRLY HVY RAIN
COULD OCCUR THIS EVE IN THE CENTRAL SHEN/HIGHLANDS B4 A QUICK END
TO THE RA HAPPENS THERE LATE TNGT.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
LOW PRESSURE WILL CONTINUE TO MOVE THROUGH THE EASTERN GREAT LAKES
TUESDAY AND INTO SOUTHERN CANADA BY TUESDAY NIGHT. THE COLD FRONT
ASSOCIATED WITH THIS SYSTEM WILL PASS THROUGH THE EASTERN PORTION OF
OUR CWA DURING THE MORNING HOURS. DEEP MOISTURE AHEAD OF THE FRONT
WILL CAUSE SHOWERS AND POSSIBLE T-STORMS TUESDAY MORNING MAINLY FOR
LOCATIONS EAST OF THE BLUE RIDGE MOUNTAINS.
STRONG DEEP LAYER SHEAR AHEAD OF THE FRONT WILL COMBINE WITH LIMITED
INSTABILITY FOR THUNDERSTORMS TO HAVE THE POTENTIAL TO PRODUCE GUSTY
WINDS MAINLY FROM WASHINGTON AND BALTIMORE METROPOLITAN AREAS
EASTWARD. AN ISOLATED TORNADO IS POSSIBLE DUE TO THE STRONG
LOW-LEVEL JET AHEAD OF THE FRONT. TIMING FOR THE SEVERE THREAT IS
STILL A LITTLE UNCERTAIN AT THIS TIME...BUT AM LEANING TOWARD A
FASTER SOLUTION THAT WOULD HAVE ANY SEVERE THREAT OFF TO OUR EAST BY
MID-MORNING.
UPSLOPE SHOWERS WILL CONTINUE TUESDAY AFTERNOON FOR LOCATIONS ALONG
AND WEST OF THE ALLEGHENY FRONT. ELSEWHERE...STRONG SUBSIDENCE FROM
THE DRY SLOT WILL BRING SOME SUNSHINE. ISOLATED SHOWERS CANNOT BE
RULED OUT WITH THE MID-LEVEL TROUGH AXIS STILL TO THE WEST. SURFACE
HIGH PRESSURE WILL BUILD OVERHEAD BEHIND THE COLD FRONT FOR TUESDAY
NIGHT AND WEDNESDAY...BRINGING DRY CONDITIONS TO MOST AREAS.
HOWEVER...UPSLOPE SHOWERS MAY STILL IMPACT LOCATIONS ALONG AND WEST
OF THE ALLEGHENY FRONT.
UPR CIRCULATION DVLPS OVER SERN CONUS WED EVE...WITH COASTAL LOPRES
XPCD TO NR COASTAL CAROLINAS THU AFTN. SHARP GRADIENT OF PCPN XPCD
WITH THIS SYSTEM...WITH PCPN MAINLY FCSTD TO IMPACT ERN ZONES. POPS
WERE INCRD DRAMATICALLY THU AND THU NGT.
HIPRES BUILDS IN THE WAKE OF THIS DEPARTING SYSTEM AS AGGRESSIVE
CDFNT CROSSES THE RGN. DRY AIR WILL HELP SUPPRESS PCPN AS SLGTLY
BLW NRML TEMPS DOMINATE.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
CONDITIONS WL BE DEGRADING TDA AS LOW PRES TRACKS FM GA ALONG THE
APLCHNS. CIGS HV ALREADY DROPPED INTO IFR CAT..AND WL LKLY RMN AT
THE LVL FOR MUCH OF THE NEXT 24 HRS. HEAVIER RA IS XPCTD THIS
AFTN/TNGT WHICH WL CAUSE VSBYS TO DROP INTO THE IFR CAT AS WELL.
THERE WL ALSO BE LO LVL WIND SHEAR THIS AFTN/TNGT AS WINDS INCRS
TO 35 KT AT FL 020.
A COLD FRONT WILL PASS THROUGH THE EASTERN TERMINALS TUESDAY
MORNING. SHOWERS AND T-STORMS ARE EXPECTED AHEAD OF THE FRONT.
T-STORMS WILL BE CAPABLE OF PRODUCING GUSTY WINDS AND LOCALLY HEAVY
RAIN. CONDITIONS WILL IMPROVE BEHIND THE FRONT BY TUESDAY AFTERNOON
WITH VFR CONDITIONS EXPECTED.
SURFACE HIGH PRESSURE WILL BUILD OVERHEAD TUESDAY NIGHT AND
WEDNESDAY. PATCHY FOG MAY REDUCE VSBYS LATE TUESDAY NIGHT INTO
WEDNESDAY MORNING. ANOTHER STORM SYSTEM MAY IMPACT THE AREA
THURSDAY.
&&
.MARINE...
TIGHTENING PRES GRAD BTWN THE HIGH OVR NRN NEW ENGLAND AND NWD
TRACKING LOW WL RESULT IN SCA WINDS ACROSS ALL THE WATERS THIS
AFTN. GALE WRNG IN EFFECT FOR MUCH OF THE BAY OVERNIGHT. BELIEF
IS THAT WINDS WL GNRLY BE IN THE SCA RANGE...BUT THERE WL BE THE
PTNL FOR RW TO BRING DOWN HIGHER WIND GUSTS AHD OF THE CD FNT DURG
THE OVRNGT HRS.
A COLD FRONT WILL PASS THROUGH THE WATERS TUESDAY MORNING. GUSTY
SOUTH-SOUTHEAST WINDS ARE EXPECTED AHEAD OF THE FRONT. SHOWERS AND
THUNDERSTORMS ARE ALSO EXPECTED AHEAD OF THE FRONT. THUNDERSTORMS
WILL BE CAPABLE OF PRODUCING GUSTY WINDS AND HEAVY RAINFALL. AN
ISOLATED WATER SPOUT IS POSSIBLE DUE TO THE STRONG LOW-LEVEL JET.
CONDITIONS WILL IMPROVE BEHIND THE COLD FRONT TUESDAY
AFTERNOON...BUT SCA WINDS ARE STILL EXPECTED. HIGH PRESSURE WILL
BUILD OVER THE WATERS FOR TUESDAY NIGHT INTO WEDNESDAY. ANOTHER
STORM SYSTEM MAY IMPACT THE WATERS THURSDAY.
&&
.HYDROLOGY...
FLASH FLD WATCH HAS BEEN ISSUED FOR TNGT FOR THE CENTRAL SHEN VLLY
AND HIGHLANDS. QPF OF 2-4" PSBL OVR MUCH OF THE AREA. SEE TDA/TNGT
DSCNS ABV FOR DETAILS.
&&
.TIDES/COASTAL FLOODING...
ONSHORE FLOW WILL INCREASING LATE THIS MORNING...AS LOW PRESSURE
TRACKS JUST WEST OF THE APPALACHIANS. TIDAL ANOMALIES NOW CLIMBING
TO NEAR A FOOT ABOVE NORMAL...ACROSS THE MD BAY /ESPECIALLY THE
NRN AND CNTRL PORTIONS/. AS THE SOUTH-SOUTHEAST FLOW
INCREASES...TIDAL ANOMALIES ARE EXPECTED TO INCREASE THROUGH
TONIGHT AND INTO TUESDAY. MINOR COASTAL FLOODING EXPECTED AT TIMES
OF HIGH TIDE FOR THIS AFTERNOON THROUGH TUESDAY. THERE IS A
BETTER CHANCE FOR MODERATE COASTAL FLOODING TONIGHT INTO TUESDAY.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...COASTAL FLOOD WATCH FROM TUESDAY MORNING THROUGH TUESDAY
AFTERNOON FOR MDZ007-011-014-017-018.
COASTAL FLOOD ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT
TUESDAY FOR MDZ007-011-014-017-018.
VA...FLASH FLOOD WATCH FROM 8 PM EDT THIS EVENING THROUGH TUESDAY
MORNING FOR VAZ021-025-026-036>038.
WV...FLASH FLOOD WATCH FROM 8 PM EDT THIS EVENING THROUGH TUESDAY
MORNING FOR WVZ054.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
ANZ531>534-539>543.
GALE WARNING FROM 8 PM THIS EVENING TO 8 AM EDT TUESDAY FOR
ANZ531>534-539>543.
SMALL CRAFT ADVISORY UNTIL 8 AM EDT TUESDAY FOR ANZ530-537-538.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 AM EDT
TUESDAY FOR ANZ535-536.
&&
UPDATE...GMS
PREV DISCUSSION...WOODY!/LASORSAHAZARDOUS WEATHER OUTLOOK...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1049 AM EDT MON SEP 27 2010 ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057- 281300- 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- 1049 AM EDT MON SEP 27 2010 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 SMALL CRAFT ADVISORY IS IN EFFECT FOR THE TIDAL POTOMAC AND MARYLAND CHESAPEAKE BAY TODAY AND TONIGHT. A GALE WARNING HAS BEEN EXTENDED INTO THE MAIN CHANNEL OF THE MARYLAND CHESAPEAKE BAY FROM 8 PM TONIGHT INTO EARLY TUESDAY MORNING. THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS ALONG THE I-95 CORRIDOR FOR LATER THIS AFTERNOON AND INTO TONIGHT. SOME STORMS WILL HAVE THE POTENTIAL TO GENERATE STRONG GUSTY WINDS...AND THE POSSIBILITY OF ISOLATED TORNADOES. A COASTAL FLOOD ADVISORY IS IN EFFECT FROM 6 PM INTO EARLY TUESDAY MORNING FOR THE WESTERN SHORES OF THE MARYLAND CHESAPEAKE BAY. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY A SMALL CRAFT ADVISORY LIKELY WILL BE NEEDED FOR THE WATERS ON TUESDAY. SHOWERS AND THUNDERSTORMS CAPABLE OF HEAVY RAIN AND STRONG GUSTY WINDS ARE POSSIBLE EARLY TUESDAY ACROSS PORTIONS OF THE AREA. A COASTAL FLOOD WATCH IS IN EFFECT FROM 6 AM TUESDAY MORNING THROUGH LATE AFTERNOON FOR THE WESTERN SHORES OF THE MARYLAND CHESAPEAKE BAY. .SPOTTER INFORMATION STATEMENT... SPOTTERS SHOULD MONITOR THE LATEST FORECASTS AND BE PREPARED FOR POSSIBLE ACTIVATION THIS AFTERNOON INTO EARLY TUESDAY. MDZ003>005-009-010-501-502-VAZ021-025>031-036>040-042-050-051-501- 502-WVZ050>055-501>504-281300- WASHINGTON-FREDERICK MD-CARROLL-MONTGOMERY-HOWARD- EXTREME WESTERN ALLEGANY-CENTRAL AND EASTERN ALLEGANY-HIGHLAND- AUGUSTA-ROCKINGHAM-SHENANDOAH-FREDERICK VA-PAGE-WARREN-CLARKE- NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-LOUDOUN-ORANGE- CULPEPER-NORTHERN FAUQUIER-SOUTHERN FAUQUIER-HAMPSHIRE-MORGAN- BERKELEY-JEFFERSON-PENDLETON-HARDY-WESTERN GRANT-EASTERN GRANT- WESTERN MINERAL-EASTERN MINERAL- 1049 AM EDT MON SEP 27 2010 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 PORTIONS OF WEST CENTRAL VIRGINIA...FROM THE CHARLOTTESVILLE AREA TO THE CENTRAL APPALACHIANS. THE WATCH IS IN EFFECT FROM 8 PM THIS EVENING THROUGH EARLY TUESDAY MORNING. THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS EAST OF THE NORTHERN VIRGINIA BLUE RIDGE FOR LATER THIS AFTERNOON AND INTO TONIGHT. SOME STORMS WILL HAVE THE POTENTIAL TO GENERATE STRONG GUSTY WINDS...AND THE POSSIBILITY OF ISOLATED TORNADOES...MAINLY EAST OF THE NORTHERN VIRGINIA BLUE RIDGE AND FOOTHILLS. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SPOTTERS SHOULD MONITOR THE LATEST FORECASTS AND BE PREPARED FOR POSSIBLE ACTIVATION THIS AFTERNOON AND TONIGHT.
SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1203 PM EDT MON SEP 27 2010 MDZ009-010-271645- HOWARD MD-MONTGOMERY MD- 1203 PM EDT MON SEP 27 2010 ...STRONG THUNDERSTORMS TO AFFECT EASTERN HOWARD AND EXTREME EASTERN MONTGOMERY COUNTIES... AT 1203 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER BURTONSVILLE...MOVING NORTH AT 25 MPH. LOCATIONS IMPACTED INCLUDE ELLICOTT CITY AND FULTON. STORM INTENSITY IS INCREASING...AND SEVERE WEATHER MAY DEVELOP RAPIDLY. REMAIN ALERT...AND BE PREPARED TO TAKE ACTION IF WARNINGS ARE ISSUED. HEAVY RAIN WITH THIS STORM MAY REDUCE VISIBILITIES TO BELOW ONE MILE AND MAY CAUSE PONDING OF WATER ON ROADWAYS. WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM. && LAT...LON 3931 7702 3930 7682 3908 7692 3909 7699 TIME...MOT...LOC 1603Z 178DEG 22KT 3910 7693 GMS
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1207 PM EDT MON SEP 27 2010
MDZ004-005-271645-
CARROLL MD-FREDERICK MD-
1207 PM EDT MON SEP 27 2010
...STRONG THUNDERSTORMS TO AFFECT CARROLL AND FREDERICK COUNTIES...
AT 1207 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER
MOUNT AIRY...MOVING NORTH AT 25 MPH.
LOCATIONS IMPACTED INCLUDE MOUNT AIRY AND TANEYTOWN.
STORM INTENSITY IS INCREASING...AND SEVERE WEATHER MAY DEVELOP
RAPIDLY. REMAIN ALERT...AND BE PREPARED TO TAKE ACTION IF WARNINGS
ARE ISSUED.
HEAVY RAIN WITH THIS STORM MAY REDUCE VISIBILITIES TO BELOW ONE MILE
AND MAY CAUSE PONDING OF WATER ON ROADWAYS.
WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM.
&&
LAT...LON 3972 7699 3937 7708 3936 7721 3972 7728
3973 7700
TIME...MOT...LOC 1607Z 184DEG 23KT 3939 7715
GMSSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1217 PM EDT MON SEP 27 2010
MDZ009-271715-
MONTGOMERY MD-
1217 PM EDT MON SEP 27 2010
...STRONG THUNDERSTORMS TO AFFECT PORTIONS OF SOUTHERN AND CENTRAL
MONTGOMERY COUNTY...
AT 1216 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM 2
MILES SOUTH OF GLEN ECHO...MOVING NORTH AT 30 MPH.
LOCATIONS IMPACTED INCLUDE ASPEN HILL...ROCKVILLE...GAITHERSBURG...
OLNEY AND MONTGOMERY VILLAGE.
STORM INTENSITY IS INCREASING...AND SEVERE WEATHER MAY DEVELOP
RAPIDLY. REMAIN ALERT...AND BE PREPARED TO TAKE ACTION IF WARNINGS
ARE ISSUED.
HEAVY RAIN WITH THIS STORM MAY REDUCE VISIBILITIES TO BELOW ONE MILE
AND MAY CAUSE PONDING OF WATER ON ROADWAYS.
WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM.
&&
LAT...LON 3922 7726 3920 7702 3895 7711 3897 7715
3898 7718
TIME...MOT...LOC 1616Z 193DEG 24KT 3896 7713
GMSSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1234 PM EDT MON SEP 27 2010
MDZ005-006-271715-
CARROLL MD-NORTHERN BALTIMORE MD-
1234 PM EDT MON SEP 27 2010
...STRONG THUNDERSTORMS TO AFFECT CARROLL AND NORTHERN BALTIMORE
COUNTIES...
AT 1234 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER
FINKSBURG...MOVING NORTH AT 30 MPH.
LOCATIONS IMPACTED INCLUDE HAMPSTEAD AND MANCHESTER.
STORM INTENSITY IS INCREASING...AND SEVERE WEATHER MAY DEVELOP
RAPIDLY. REMAIN ALERT...AND BE PREPARED TO TAKE ACTION IF WARNINGS
ARE ISSUED.
HEAVY RAIN WITH THIS STORM MAY REDUCE VISIBILITIES TO BELOW ONE MILE
AND MAY CAUSE PONDING OF WATER ON ROADWAYS.
WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM.
&&
LAT...LON 3957 7700 3965 7702 3969 7695 3965 7684
3947 7684 3945 7688 3946 7692
TIME...MOT...LOC 1634Z 169DEG 25KT 3949 7689
GMSSPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1237 PM EDT MON SEP 27 2010
MDZ009-010-271715-
HOWARD MD-MONTGOMERY MD-
1237 PM EDT MON SEP 27 2010
...STRONG THUNDERSTORMS TO AFFECT HOWARD AND MONTGOMERY COUNTIES...
AT 1237 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER
ASPEN HILL...MOVING NORTH AT 25 MPH.
LOCATIONS IMPACTED INCLUDE OLNEY....ROCKVILLE...ASPEN HILL AND
NORBECK.
STORM INTENSITY IS INCREASING...AND SEVERE WEATHER MAY DEVELOP
RAPIDLY. REMAIN ALERT...AND BE PREPARED TO TAKE ACTION IF WARNINGS
ARE ISSUED.
HEAVY RAIN WITH THIS STORM MAY REDUCE VISIBILITIES TO BELOW ONE MILE
AND MAY CAUSE PONDING OF WATER ON ROADWAYS.
WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM.
&&
LAT...LON 3926 7717 3933 7714 3930 7696 3905 7702
3907 7711
TIME...MOT...LOC 1637Z 185DEG 23KT 3909 7707
GMSSPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 112 PM EDT MON SEP 27 2010 MDZ005-010-271800- CARROLL MD-HOWARD MD- 112 PM EDT MON SEP 27 2010 ...STRONG THUNDERSTORMS TO AFFECT CARROLL AND HOWARD COUNTIES... AT 112 PM EDT...DOPPLER RADAR INDICATED A STRONG THUNDERSTORM OVER GLENWOOD...MOVING NORTH AT 25 MPH. LOCATIONS IMPACTED INCLUDE SYKESVILLE AND ELDERSBURG. STORM INTENSITY IS INCREASING...AND SEVERE WEATHER MAY DEVELOP RAPIDLY. REMAIN ALERT...AND BE PREPARED TO TAKE ACTION IF WARNINGS ARE ISSUED. HEAVY RAIN WITH THIS STORM MAY REDUCE VISIBILITIES TO BELOW ONE MILE AND MAY CAUSE PONDING OF WATER ON ROADWAYS. WIND GUSTS OF 40 TO 50 MPH CAN BE EXPECTED WITH THIS STORM. && LAT...LON 3944 7708 3944 7691 3925 7696 3927 7706 TIME...MOT...LOC 1712Z 184DEG 22KT 3929 7701 GMS
The Sterling radar (KLWX), 34 km away, was scanning. The volume nearest the first event began at 17:22 UTC.
1 flash flood. Local standard time, as filed.
Flash Flooding was reported at the intersection of Route 28 and Avery Road. There was also additional flooding along Rock Creek.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Maryland in 2010Every state in 2010This day in weather historyWarnings in Maryland, September 2010
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: 257326.