Alert archive / Virginia / Flash Flood Warnings in 2001
Flash Flood Warning 41, NWS Baltimore/Washington
NWS Baltimore/Washington issued this flash flood warning at Aug 11, 2001, 4:16 PM EDT for Howard County, Montgomery County, Prince George's County, Maryland; 11 counties in Virginia. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.
The area
The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties.
The facts
- Issued
- Aug 11, 2001, 4:16 PM EDT (20:16 UTC)
- Expired
- Aug 11, 2001, 6:30 PM EDT
- In force
- 2 hr
- Issued by
- NWS Baltimore/Washington
- Area
- Whole counties; the outline is the Mesonet’s reconstruction
Counties Howard County, MD, Montgomery County, MD, Prince George's County, MD, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Loudoun County, VA, Prince William County, VA
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 12:00Z, 8.3 hours before the alert went out and 13 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 725 J/kg
- Mixed-layer CIN
- -68 J/kg
- Mixed-layer LCL
- 880 m above ground
- 0-6 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- -4 m²/s²
- 0-3 km storm-relative helicity
- 19 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000 WGUS51 KLWX 112025 FFWLWX DCC001-MDC027-031-033-VAC013-107-047-059-061-153-510-600-610-683-685- 112230- BULLETIN - EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE BALTIMORE-WASHINGTON 416 PM EDT SAT AUG 11 2001 THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A * FLASH FLOOD WARNING FOR... DISTRICT OF COLUMBIA IN DISTRICT OF COLUMBIA HOWARD COUNTY IN CENTRAL MARYLAND MONTGOMERY COUNTY IN CENTRAL MARYLAND PRINCE GEORGES COUNTY IN CENTRAL MARYLAND ARLINGTON COUNTY IN NORTHERN VIRGINIA CITY OF ALEXANDRIA IN NORTHERN VIRGINIA CITY OF FAIRFAX IN NORTHERN VIRGINIA CITY OF FALLS CHURCH IN NORTHERN VIRGINIA CITY OF MANASSAS IN NORTHERN VIRGINIA CITY OF MANASSAS PARK IN NORTHERN VIRGINIA CULPEPER COUNTY IN NORTHERN VIRGINIA FAIRFAX COUNTY IN NORTHERN VIRGINIA FAUQUIER COUNTY IN NORTHERN VIRGINIA PRINCE WILLIAM COUNTY IN NORTHERN VIRGINIA EASTERN LOUDOUN COUNTY * UNTIL 630 PM EDT * AT 415 PM EDT...WEATHER SERVICE DOPPLER RADAR INDICATED A LINE OF THUNDERSTORMS WITH TORRENTIAL RAINFALL FROM HOWARD AND MONTGOMERY COUNTIES SOUTH ACROSS THE DISTRICT OF COLUMBIA FAIRFAX COUNTY PRINCE GEORGES EASTERN LOUDOUN PRINCE-WILLIAM FAUQUIER AND CULPEPER COUNTIES. THIS LINE OF THUNDERSTORMS WAS NEARLY STATIONARY AND PRODUCING RAINFALL RATES OF 2 TO 3 INCHES PER HOUR. FLOODING HAS ALREADY BEEN REPORTED IN MONTGOMERY COUNTY. EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF SMALL CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS. EXCESSIVE RUNOFF FROM THIS STORM WILL CAUSE FLASH FLOODING OF SMALL CREEKS AND STREAMS...COUNTRY ROADS...OTHER POOR DRAINAGE OR LOW LYING AREAS. IF WATER IS FLOWING ACROSS A ROADWAY TURN YOUR VEHICLE AROUND AND FIND AN ALTERNATE ROUTE. THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO CROSS SAFELY. VEHICLES CAUGHT IN RISING WATER SHOULD BE ABANDONED QUICKLY. MOVE TO HIGHER GROUND. A FLASH FLOOD WARNING MEANS THAT FLOODING IS OCCURRING OR IS IMMINENT. MOST FLASH FLOOD DEATHS OCCUR IN AUTOMOBILES. IF YOU ENCOUNTER WATER FLOWING ACROSS BRIDGES...DIPS...OR OTHER LOW SPOTS TURN AROUND AND FIND AN ALTERNATE ROUTE. NEVER TRY TO CROSS A FLOWING STREAM...EVEN A SMALL ONE...ON FOOT. TO ESCAPE RISING WATER MOVE UP TO HIGHER GROUND. A FLASH FLOOD WARNING MEANS THAT FLOODING IS IMMINENT OR OCCURRING. IF YOU ARE IN THE WARNING AREA MOVE TO HIGHER GROUND IMMEDIATELY. RESIDENTS LIVING ALONG STREAMS AND CREEKS SHOULD TAKE IMMEDIATE PRECAUTIONS TO PROTECT LIFE AND PROPERTY. DO NOT ATTEMPT TO CROSS SWIFTLY FLOWING WATERS OR WATERS OF UNKNOWN DEPTH BY FOOT OR BY AUTOMOBILE. IF YOUR VEHICLE STALLS, ABANDON IT IMMEDIATELY AND SEEK HIGHER GROUND. LAT...LON 3927 7699 3842 7800 3842 7793 3880 7684 $$ JLW/ABW
What forecasters said that day
The local office's own words before this flash flood warning went out, 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 this flash flood warning went out at Aug 11, 2:05 PM EDT, 2 hours 11 minutes earlier.
Area forecast discussion, Aug 11, 2:05 PM EDT, 2 hours 11 minutes before
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.
In the hours before
Local storm report, Aug 11, 11:15 AM EDT, 5 hours 1 minute before
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
WALSTONLocal storm report, Aug 11, 11:15 AM EDT, 5 hours 1 minute before
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
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
WALSTONSpecial weather statement, Aug 11, 4:10 PM EDT, 6 minutes before
DCZ001-MDZ004>007-009>011-013-014-016>018-VAZ021-025>031-036>042- 050>057-WVZ048-054-055-112300- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE BALTIMORE-WASHINGTON 410 PM EDT SAT AUG 11 2001 ...NUMEROUS THUNDERSTORMS WITH TORRENTIAL RAINS... AT 410 PM EDT DOPPLER RADAR SHOWED NUMEROUS SLOW MOVING STRONG THUNDERSTORMS OVER A WIDE AREA OF NORTHERN AND CENTRAL VIRGINIA AND CENTRAL AND SOUTHERN MARYLAND. MANY OF THE STORMS WERE CONCENTRATED IN AN AREA FROM HOWARD AND MONTGOMERY COUNTIES SOUTH ACROSS THE DISTRICT PRINCE-GEORGES CHARLES FAIRFAX PRINCE-WILLIAM FAUQUIER COUNTIES AND THROUGH THE CENTRAL PIEDMONT COUNTIES OF MADISON ORANGE AND ALBEMARLE. THE GENERAL MOVEMENT OF THESE STORMS WAS A SLOW DRIFT TOWARD THE NORTHEAST BUT MANY WERE SHOWING ERRATIC MOVEMENT OR WERE NEARLY STATIONARY. THE PRIMARY THREAT FROM THESE IS LOCALLY VERY HEAVY RAINS CAPABLE OF PRODUCING RAINFALL RATES OF 2 TO 3 INCHES PER HOUR. LOCALIZED FLOODING OF SMALL STREAMS CREEKS AND PONDING OF WATER ON ROADWAYS UNDERPASSES AND OTHER LOW LYING AREAS IS A DISTINCT POSSIBILTY INTO THIS EVENING UNTIL AT LEAST 6 TO 8 PM. RESIDENTS IN FLOOD PRONE AREAS SHOULD BE ALERT FOR HEAVY RAINS IN THEIR AREA AND BE PREPARED TO SEEK HIGHER GROUND SHOULD FLOODING BE OBSERVED. MOTORISTS SHOULD UNDER NO CIRCUMSTANCE ATTEMPT TO DRIVE INTO FLOOD WATERS. LOCALLY GUSTY WINDS AND HAIL ARE ALSO POSSIBLE IN THE STRONGER THUNDERSTORMS. STAY TUNED TO NOAA WEATHER RADIO AND OTHER LOCAL MEDIA FOR FURTHER DETAILS OR UPDATES. FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT HTTP://WWW.NWS.NOAA.GOV/ER/LWX JLW
The office that day
Everything else NWS Baltimore/Washington issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 11, 2:23 PM EDT | Flash Flood Warning | LWX | Harford | 97 min |
| Aug 11, 12:36 PM EDT | Flash Flood Warning | LWX | Nelson | 114 min |
| Aug 11, 5:43 PM EDT | Flash Flood Warning | LWX | Clarke, Loudoun | 2 hr |
| Aug 11, 6:10 PM EDT | Flash Flood Warning | LWX | Frederick, City of Winchester | 110 min |
Nearby
Flash Flood Warnings in Virginia, 2001Flash Flood Warnings in Maryland, 2001Flash Flood Warnings in District of Columbia, 2001Every flash flood warning in 2001
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.