Alert archive / Virginia / Flash Flood Warnings in 2011

Flash Flood Warning 125, NWS Baltimore/Washington

September 4, 2011Frederick County, Shenandoah County, Virginia; Hampshire County, Hardy County, West Virginia

NWS Baltimore/Washington issued this flash flood warning at Sep 4, 2011, 10:28 PM EDT for Frederick County, Shenandoah County, Virginia; Hampshire County, Hardy County, West Virginia. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Sep 4, 2011, 10:28 PM EDT (02:28 UTC)
Expired
Sep 5, 2011, 1:30 AM EDT
In force
3 hr
Issued by
NWS Baltimore/Washington
Area
Storm-based polygon
Flood severity
None

Counties Frederick County, VA, Shenandoah County, VA, Hampshire County, WV, Hardy County, WV

The radar

The Sterling radar (KLWX), 95 km from the middle of the area, began a volume at 02:29 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 2.5 hours before the alert went out and 103 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.

Skew-T log-pSkew-T log-p diagram, Washington/Dulle, VA at 00:00Z on 2011-09-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2382 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 00:00Z on 2011-09-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 63 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
2382 J/kg
Mixed-layer CIN
-2 J/kg
Mixed-layer LCL
895 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
63 m²/s²
0-3 km storm-relative helicity
64 m²/s²
Significant tornado parameter
0.3
Supercell composite
2.2

Open this sounding in Storm Lab

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 Sep 4, 9:24 PM EDT, 1 hour 4 minutes earlier.

Area forecast discussion, Sep 4, 9:24 PM EDT, 1 hour 4 minutes before
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Hazardous weather outlook, Sep 4, 8:08 PM EDT, 2 hours 20 minutes before
HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
808 PM EDT SUN SEP 4 2011

ANZ530>543-DCZ001-MDZ006-007-011-013-014-016>018-VAZ052>057-
051315-
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-
808 PM EDT SUN SEP 4 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

MINOR COASTAL FLOODING IS ANTICIPATED AROUND THE HIGH TIDE TONIGHT
ALONG THE UPPER PORTIONS OF THE TIDAL POTOMAC RIVER AND WESTERN
SHORES OF THE MARYLAND CHESAPEAKE BAY. A COASTAL FLOOD ADVISORY
HAS BEEN ISSUED FOR THE EVENING AND OVERNIGHT HIGH TIDE CYCLE. SEE
WBCCFWLWX FOR FURTHER DETAILS.

A SMALL CRAFT ADVISORY IS IN EFFECT TONIGHT FOR MUCH OF THE
MARYLAND CHESAPEAKE BAY AND THE LOWER TIDAL POTOMAC RIVER
TONIGHT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

THE SMALL CRAFT ADVISORY FOR MUCH OF THE MARYLAND CHESAPEAKE BAY
AND THE LOWER TIDAL POTOMAC RIVER CONTINUES THROUGH MONDAY.

SHOWERS AND THUNDERSTORMS MAY PRODUCE VERY HEAVY RAINFALL MONDAY
AND TUESDAY AS TROPICAL MOISTURE INTERACTS WITH A SLOW-MOVING COLD
FRONT. FLASH FLOODING MAY RESULT. HEAVY PRECIPITATION AND
POTENTIAL FLOODING COULD LAST WELL INTO NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TONIGHT.

MDZ003>005-009-010-501-502-VAZ025>031-036>040-042-050-051-501>504-
WVZ050>053-055-501>506-051315-
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-
808 PM EDT SUN SEP 4 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

THUNDERSTORMS ARE LIKELY WEST OF THE BLUE RIDGE THIS AFTERNOON
THROUGH TONIGHT. A FEW STORMS MAY BECOME SEVERE...WITH THE
POTENTIAL TO PRODUCE DAMAGING WIND GUSTS...LARGE HAIL AND LOCALLY
HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

SHOWERS AND THUNDERSTORMS MAY PRODUCE VERY HEAVY RAINFALL MONDAY
AND TUESDAY AS TROPICAL MOISTURE INTERACTS WITH A SLOW-MOVING COLD
FRONT. FLASH FLOODING MAY RESULT. HEAVY PRECIPITATION AND
POTENTIAL FLOODING COULD LAST WELL INTO NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TONIGHT.

In the hours before

Special weather statement, Sep 4, 5:07 PM EDT, 5 hours 21 minutes before
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
507 PM EDT SUN SEP 4 2011

MDZ501-502-WVZ050-055-501>505-042130-
HARDY WV-HAMPSHIRE WV-WESTERN GRANT WV-EASTERN GRANT WV-
CENTRAL AND EASTERN ALLEGANY MD-EXTREME WESTERN ALLEGANY MD-
WESTERN MINERAL WV-EASTERN MINERAL WV-WESTERN PENDLETON WV-
507 PM EDT SUN SEP 4 2011

...STRONG THUNDERSTORMS WITH HEAVY RAINFALL TO AFFECT
HARDY...HAMPSHIRE...GRANT...ALLEGANY...MINERAL AND WESTERN PENDLETON
COUNTIES...

AT 502 PM EDT...DOPPLER RADAR INDICATED STRONG THUNDERSTORMS ALONG A
LINE EXTENDING FROM 3 MILES WEST OF NEW CREEK TO 2 MILES SOUTH OF
MOUNT STORM TO KLINE GAP TO 6 MILES SOUTHWEST OF HOPEVILLE...MOVING
NORTHEAST AT 25 MPH.

THESE THUNDERSTORMS WILL PROVIDE THE MOUNTAIN COMMUNITIES OF
GRANT...MINERAL...AND NORTHWESTERN PENDLETON COUNTIES WITH
TORRENTIAL RAINFALL. TWO INCHES OF RAIN WILL BE POSSIBLE WITHIN AN
HOUR. THESE RAINFALL RATES WILL CAUSE RAPID WITHIN BANK RISES ON
CREEKS AND STREAMS...AS WELL AS CAUSE PONDING OF WATER IN LOW LYING
AREAS. RURAL UNPAVED ROADS MAY BECOME DIFFICULT TO CROSS.

AREA RESIDENTS SHOULD MONITOR THE LATEST WEATHER CONDITIONS FOR ANY
POSSIBLE WARNINGS. IF YOU LIVE OR CAMP IN A LOW LYING AREA...ALWAYS
SEEK HIGHER GROUND IF RAPID STREAM LEVEL RISES THREATEN YOUR
LOCATION.

&&

LAT...LON 3967 7875 3947 7896 3928 7895 3899 7912
      3887 7934 3889 7944 3895 7936 3906 7930
      3909 7934 3916 7934 3919 7930 3921 7931
      3921 7934 3940 7914
TIME...MOT...LOC 2102Z 224DEG 23KT 3938 7907 3926 7923
          3907 7921 3891 7936

HTS

The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 5, 4:06 AM EDTFlash Flood WatchLWXArlington, Clarke, Culpeper, Fairfax, Fauquier, Frederick and 22 more5 days
Sep 5, 1:41 PM EDTCoastal Flood AdvisoryLWXArlington, Fairfax, King George, Stafford, City of Alexandria, City of Fairfax and 1 more16 hr
Sep 4, 11:54 PM EDTSpecial Weather StatementLWXCarroll, Frederick66 min
Sep 5, 3:05 PM EDTSpecial Weather StatementLWXBaltimore, City of Baltimore25 min
Sep 5, 3:36 PM EDTSpecial Weather StatementLWXPrince George's24 min

Nearby

Flash Flood Warnings in Virginia, 2011Flash Flood Warnings in West Virginia, 2011Every flash flood warning in 2011

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; radar from the NEXRAD Level II archive.