Alert archive / Virginia / Flash Flood Warnings in 2012

Flash Flood Warning 2, NWS Baltimore/Washington

May 21, 2012Prince William County, City of Manassas, Virginia

NWS Baltimore/Washington issued this flash flood warning at May 21, 2012, 11:57 PM EDT for Prince William County, City of Manassas, Virginia. It was in force for 3 hr. 14 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
May 21, 2012, 11:57 PM EDT (03:57 UTC)
Expired
May 22, 2012, 3:00 AM EDT
In force
3 hr
Issued by
NWS Baltimore/Washington
Area
Storm-based polygon
Flood severity
None

Counties City of Manassas, VA, Prince William County, VA

The radar

The Sterling radar (KLWX), 24 km from the middle of the area, began a volume at 04:00 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.

What was reported inside it

TimeReportWhereRemark
May 22, 12:02 AM EDTFLASH FLOOD2 Ese Gainesville, VAWELLINGTON ROAD AT PINEY BRANCH LANE CLOSED DUE TO FLOODING
May 22, 12:20 AM EDTFLASH FLOODGainesville, VAJOHN MARSHALL HIGHWAY AND CARTHARPIN ROAD CLOSED DUE TO HIGH WATER
May 22, 12:30 AM EDTFLASH FLOOD2 Ne Nokesville, VANOKESVILLE ROAD AT AIDEN ROAD SR 646 CLOSED DUE TO WATER OVER THE ROAD
May 22, 12:30 AM EDTFLASH FLOOD3 Se Gainesville, VADEVLIN ROAD AT ASHELEYS PARK LANE CLOSED DUE TO WATER OVER THE ROAD.
May 22, 12:30 AM EDTFLASH FLOOD3 W Bull Run, VADEVLIN ROAD AT JENNELL DRIVE CLOSED DUE TO HIGH WATER
May 22, 12:54 AM EDTFLASH FLOOD2 Se Gainesville, VALINTON HALL ROAD AT HARNESS SHOP ROAD CLOSED DUE TO FLOODING.
May 22, 1:07 AM EDTFLASH FLOOD2 Wnw Bull Run, VAPRINCE WILLIAM PARKWAY AT BALLS FORD ROAD CLOSED DUE TO FLOODING.
May 22, 1:22 AM EDTFLASH FLOOD2 Ene Gainesville, VAUS 29 LEE HIGHWAY AND PAGELAND LANE CLOSED DUE TO FLOODING
May 22, 1:24 AM EDTFLASH FLOODCatharpin, VASANDERS LANE AT SUDLEY ROAD CLOSED DUE TO FLOODING
May 22, 1:26 AM EDTFLASH FLOOD2 S Catharpin, VAPAGELAND LANE AT ARTEMUS ROAD CLOSED DUE TO FLOODING.
May 22, 1:29 AM EDTFLASH FLOOD1 N Gainesville, VAHEATHCOTE BLVD AT CARTHARPIN ROAD CLOSED DUE TO FLOODING.
May 22, 1:30 AM EDTFLASH FLOODAden, VASWIFT WATER RESCUE.
May 22, 2:00 AM EDTFLASH FLOOD1 Se Aden, VASECTION OF ADEN ROAD AT MISTY CREEK COURT WAS WASHED OUT DUE TO HEAVY RAINFALL LEADING TO FLASH FLOODING. TIME OF WASHOUT IS ESTIMATED.
May 22, 3:00 AM EDTFLASH FLOOD2 N Aden, VAPART OF ROADWAY WASHED OUT DUE TO FLASH FLOODING ALONG VALLEY VIEW DR NEAR NOKESVILLE. TIME IS ESTIMATED.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 00:00Z, 4.0 hours before the alert went out and 24 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 2012-05-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 278 joules per kilogram.LCLEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 00:00Z on 2012-05-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -41 square meters per square second.1939Sfc1 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
278 J/kg
Mixed-layer CIN
-1 J/kg
Mixed-layer LCL
601 m above ground
0-6 km bulk shear
2 kt
0-1 km storm-relative helicity
-41 m²/s²
0-3 km storm-relative helicity
19 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

476 
WGUS51 KLWX 220357
FFWLWX
VAC153-683-220700-
/O.NEW.KLWX.FF.W.0002.120522T0357Z-120522T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1157 PM EDT MON MAY 21 2012

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CITY OF MANASSAS IN NORTHERN VIRGINIA...
  WESTERN PRINCE WILLIAM COUNTY IN NORTHERN VIRGINIA...

* UNTIL 300 AM EDT

* AT 1149 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  VERY HEAVY RAIN FROM MANASSAS...HAYMARKET...AND NOKESVILLE SOUTHWARD
  INTO EASTERN FAUQUIER COUNTY. THIS RAIN IS TRAINING REPEATEDLY OVER 
  THE SAME AREA.

* SOME LOCATIONS THAT WILL CONTINUE TO BE AFFECTED BY THE HEAVY RAIN
  INCLUDE BULL RUN AND MANASSAS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS INCLUDES THE FOLLOWING STREAMS AND DRAINAGE...
LITTLE BULL RUN...BULL RUN...ROCKY BRANCH...BROAD RUN...CEDAR RUN...
LICK BRANCH...DAWKINS BRANCH...CANNON BRANCH...SOUTH RUN...KETTLE
RUN...OCCOQUAN RIVER...CABIN RUN...YOUNGS BRANCH...HOLKUMS BRANCH AND
CATHARPIN CREEK.

RAINFALL AMOUNTS OF 2 TO 3 INCHES HAVE FALLEN THIS EVENING...AND 
ADDITIONAL AMOUNTS OF 1 TO 3 INCHES ARE POSSIBLE.

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...HIGHWAYS AND UNDERPASSES. ADDITIONALLY...COUNTRY
ROADS AND FARMLANDS ALONG THE BANKS OF CREEKS...STREAMS AND OTHER LOW
LYING AREAS ARE SUBJECT TO FLOODING.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

&&

LAT...LON 3886 7758 3875 7744 3862 7755 3876 7766

$$
KONARIK
1 follow-up statement
191 
WGUS71 KLWX 220448
FFSLWX

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1248 AM EDT TUE MAY 22 2012

VAC153-683-220700-
/O.CON.KLWX.FF.W.0002.000000T0000Z-120522T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
CITY OF MANASSAS VA-PRINCE WILLIAM VA-
1248 AM EDT TUE MAY 22 2012

...A FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 300 AM EDT FOR
WESTERN PRINCE WILLIAM AND CITY OF MANASSAS COUNTIES...

AT 1241 AM EDT...LOCAL LAW ENFORCEMENT OFFICIALS REPORTED NUMEROUS 
ROADS CLOSED BETWEEN NOKESVILLE AND GAINESVILLE DUE TO FLASH FLOODING.  
VERY HEAVY RAIN CONTINUES OVER THE WARNED AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

RAINFALL AMOUNTS OF 2 TO 4 INCHES HAVE FALLEN...AND ADDITIONAL AMOUNTS 
OF 1 TO 2 INCHES ARE LIKELY.

MOST FLOOD DEATHS OCCUR IN AUTOMOBILES. NEVER DRIVE YOUR VEHICLE INTO
AREAS WHERE THE WATER COVERS THE ROADWAY. FLOOD WATERS ARE USUALLY
DEEPER THAN THEY APPEAR. JUST ONE FOOT OF FLOWING WATER IS POWERFUL
ENOUGH TO SWEEP VEHICLES OFF THE ROAD. WHEN ENCOUNTERING FLOODED
ROADS MAKE THE SMART CHOICE...TURN AROUND...DONT DROWN.

&&

LAT...LON 3886 7758 3875 7744 3862 7755 3876 7766

$$
KONARIK

The office that day

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

IssuedProductOfficeCountiesLasted
May 21, 8:58 PM EDTCoastal Flood AdvisoryLWXArlington, City of Alexandria, City of Falls Church15 hr
May 21, 11:17 PM EDTSpecial Weather StatementLWXLoudoun, Prince William, City of Manassas, City of Manassas Park88 min
May 22, 12:58 AM EDTSpecial Weather StatementLWXPrince William, Spotsylvania, Stafford, City of Fredericksburg, City of Manassas, City of Manassas Park92 min
May 22, 1:05 AM EDTFlash Flood WarningLWXLoudoun3 hr
May 22, 1:26 AM EDTFlash Flood WarningLWXFauquier, Prince William, Stafford, City of Manassas3 hr
May 22, 7:21 AM EDTAreal Flood WarningLWXFauquier, Prince William, City of Manassas, City of Manassas Park7 hr
May 22, 2:18 PM EDTAreal Flood WarningLWXPrince William, City of Manassas, City of Manassas Park3 hr
May 22, 5:06 PM EDTSpecial Weather StatementLWXAlbemarle, City of Charlottesville39 min
May 22, 5:40 PM EDTSpecial Weather StatementLWXAlbemarle65 min
May 22, 6:01 PM EDTSevere Thunderstorm WarningLWXNelson29 min
May 22, 7:16 PM EDTFlash Flood WatchLWXClarke, Fauquier8 hr

Nearby

Flash Flood Warnings in Virginia, 2012Every flash flood warning in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.