Alert archive / Virginia / Flash Flood Warnings in 2013

Flash Flood Warning 65, NWS Baltimore/Washington

July 12, 2013Fairfax County, Prince William County, Stafford County, Virginia

NWS Baltimore/Washington issued this flash flood warning at Jul 12, 2013, 2:12 AM EDT for Fairfax County, Prince William County, Stafford County, 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
Jul 12, 2013, 2:12 AM EDT (06:12 UTC)
Expired
Jul 12, 2013, 5:15 AM EDT
In force
3 hr
Issued by
NWS Baltimore/Washington
Area
Storm-based polygon
Flood severity
None

Counties Fairfax County, VA, Prince William County, VA, Stafford County, VA

The radar

The Sterling radar (KLWX), 37 km from the middle of the area, began a volume at 06:16 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, 6.2 hours before the alert went out and 33 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 2013-07-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 281 joules per kilogram.LCLLFCEL10008507005003002001001 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 2013-07-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -19 square meters per square second.19395878Sfc1 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
281 J/kg
Mixed-layer CIN
-20 J/kg
Mixed-layer LCL
1429 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
-19 m²/s²
0-3 km storm-relative helicity
20 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.2

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 Jul 11, 9:31 PM EDT, 4 hours 41 minutes earlier.

Area forecast discussion, Jul 11, 9:31 PM EDT, 4 hours 41 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
931 PM EDT THU JUL 11 2013

.SYNOPSIS...
A COLD FRONT WILL REMAIN STALLED OVER THE DELMARVA PENINSULA AND
SOUTHEASTERN VIRGINIA THROUGH THIS WEEKEND. HIGH PRESSURE WILL
BUILD WEST FROM THE WESTERN ATLANTIC EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH FRIDAY/...

LTST SFC ANALY DEPICTS A STALLED CDFNT ALONG THE I-95 CRRDR...
WHILE HIPRES RESIDES OVER THE GRTLKS. AN ANIMATION OF WATER
VAPOR IMGRY SUGGESTS AN UPR LOW ROTATING ABV THE SFC HIGH...ALSO
OVER THE GRTLKS.

ALTHO CWFA WL BE ON THE NW SIDE OF THE CDFNT...THERE ARE SVRL
FACTORS SUPPORTING A ROUND OF SHRA/TSRA OVNGT...AS EVIDENCED BY
RECENT RADAR TRENDS. FIRST...HGTS WL BE DROPPING AS THE UPR LOW
NEARS. SECONDLY...THE CWFA WL BE W/IN RRQ OF AN UPR JET. ITS ONLY
ABT 60-70 KT...BUT IT/S SUFFICIENT TO SUPPORT LIFT. THIRD...
BELIEVE THAT THERE ARE/WL BE A CPL WK IMPULSES GLIDING ALONG THE
STALLED SFC BNDRY.

RECENT HRRR RUNS VERIFYING QUITE NICELY...AS SWRN CWFA FILLING IN
W/ PCPN ECHOES. HV ALREADY ADJUSTED DATABASE TO EMPHASIZE THAT
AREA FOR THE EVNG HRS. HV ALSO PAINTED THE OVNGT HRS ON THE WET
SIDE...W/ LKLY POPS JUST ABT EVERYWHERE AFTER MIDNGT. 00Z RAOBS
HINT AT MINIMAL INSTBY W/ A SMALL CAP. WL PLACE MORE WEIGHT ON
SHRA...BUT THINK THAT THERE WL BE ENUF ELEVATED INSTBY FOR A FEW
RUMBLES TOO.

THAT ROUND OF SHRA/STORMS SHUD CLR AREA BY SUNRISE. IN SPITE OF
LMTD INSTBY TMRW...THE H5 LOW WL BE CLOSEST TO CWFA DURING THE DAY.
WITH THAT IN MIND...COGNIZANT OF THE UPR JET SUPPORT...AND HINTS
AT SOME MID LVL OVERRUNNING...THINK THERE SHUD BE A 2ND ROUND OF
SHRA /OR MAYBE A STORM/ FRI AFTN. AFTER REDUCING POPS INTO CHC
FOR MOST AREAS...HV TAKEN IT BACK UP TO LKLY AGN FOR THE AFTN HRS.

ANY CHGS TO TEMPS/DEWPTS WL BE MINIMAL BASED ON LTST LAMP GDNC.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
HIGH PRESSURE CONTINUES TO MOVE WESTWARD AND PUSH MOISTURE INTO THE
REGION. ROUNDS OF SHOWERS WILL MOVE ACROSS THE MID ATLANTIC INTO
SATURDAY. AS THE HIGH MOVES WESTWARD MOISTURE WILL MOVE TO THE
MOUNTAINS AND SUBSIDENCE WILL KICK IN OVER AREAS EAST OF THE BLUE
RIDGE.  EASTERLY FLOW WILL CONTINUE THE BELOW NORMAL TEMP PERIOD.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
IN JULY THE MAJOR WX PROBLEMS WHICH COME TO MIND ARE HIGH HEAT..
SVR STORMS..AND FLSH FLDG. IT APPEARS THAT ALL OF THESE WL BE HELD
AT BAY DURG THE XTND PD. IF THE GFS IS TO BE BLVD...THE COMING UPR
LVL PATTERN IS SOMEWHAT OF AN ANACHRONISM FOR MID JUL. NRMLY ONE
WOULD XPCT TO SEE A SUBTROPICAL HIGH PARKED OFF THE CST BRINGING A
STREAM OF WARM MOIST AIR INTO THE MID ALTC WHICH WOULD BRING ABT
THE PSBLTY OF AFTN/EVE TSTMS...W/ THE PTNL FOR HEAT INDICES
REACHING ADSRY LVL.

OVR THE WKND THAT LOW IS SUPPOSED TO TRACK SLOWLY TO THE W AS
HIGH PRES CENTERED NEAR LONG ISLAND BUILDS INTO THE MID ALTC. THIS
WL KEEP THE NRML MID-JUL TROPICAL CHARACTERISTICS AT BAY - XPCT TO
SEE HIGHS IN THE 80S W/ LOWS IN THE L70S E OF I-95...60S W.

AS NEXT WK PROGRESSES THAT HIGH LOOKS TO TRACK FURTHER S...MOST
LKLY CAUSING THAT AIR MASS IN THE MID ATLC TO MODIFY AND BECOME
MORE "TYPICAL" W/ INCRSG HEAT AND HUMIDITY. PCPN LOOKS TO BE HELD
AT BAY THRU MID WK.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
SHRA/TSRA WL BECOME MORE NMRS OVNGT. VSBY IMPACTS WL BE LCLZD...
BUT POTENTIALY AOB IFR. DUE TO DIFFICULTIES PINPOINTING SPECIFICS
IN A TAF STYLE FCST...HV KEPT VSBYS IN MVFR. WL ADD DETAILS
IF/WHEN THAT BECOMES CLR. CIGS...ON THE OTHER HAND...SHUD BE
LWRG...SPCLY IN THE S/W WHERE RESIDUAL MSTR WL BE LEFT BHD BY
DAWN. ON TOP OF MVFR CIGS EVERYWHERE...AM TAKING STRONG GDNC
SIGNALS OF IFR FOR CHO.

FRI WL BE AN UNSETTLED DAY. AN UPR LOW WL ROTATE TWD AREA...
SUGGESTING THAT ANY BONOVC WL ONLY QUICKLY FILL BACK IN.
FURTHER...NLY SFC FLOW AND ELY FLOW JUST OFF THE SFC WL INHIBIT
MUCH DRYING W/IN THE COLUN. DO NOT XPCT CIGS TO RISE MUCH FM LVLS
JUST AFTER SUNRISE. FURTHER SHRA WL ONLY REINFORCE POTL
RESTRICTIONS. CONDS CUD REALLY DROP FRI NGT AS RAFL EXITS BUT
MOIST LLVL CONDS PREVAIL.

DIURNAL SHRA/TSRA WL BECOME INCRSGLY SCARCE THRU THE WKND INTO ELY
NEXT WK. THAT MEANS THAT VFR WL PREVAIL FOR A MAJORITY OF THE TIME.

&&

.MARINE...
LGT SLY FLOW OVER THE WATERS THIS EVNG. STALLED CDFNT WL BE
NEARBY...SO WINDS SHUD REMAIN LGT. WATERS WL EXPERIENCE A ROUND OF
SHRA/TSRA OVNGT. WINDS MAY GET A LTL GUSTY...BUT SUSPECT THAT HVY
RAIN WL BE THE PRIMARY THREAT.

MAY BE ABLE TO NUDGE THE FNT EWD FRI. IF SO...THERE CUD BE A SMALL
SURGE IN WNDS. DO NOT HV HIGH CONFIDENCE IN THAT SCENARIO ATTM.
CONCERNS ARE THAT AN APPROACHING UPR LOW WL SUPPORT MORE SHRA/TSRA
INSTEAD. DO NOT BELIEVE THAT ANYTHING WL BE STRONG ENUF FOR
SPECIAL MARINE WARNINGS AS THE LLVLS WL BE ON THE STBL SIDE.

HIGH PRES IS XPCTD TO BUILD INTO THE WATERS OVR THE WKND/INTO
NEXT WK. NO PROBS XPCTD.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

SYNOPSIS...HTS
NEAR TERM...HTS
SHORT TERM...HAS
LONG TERM...WOODY!
AVIATION...HTS
MARINE...HTS/WOODY!
Hazardous weather outlook, Jul 12, 1:43 AM EDT, 29 minutes before
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In the hours before

Local storm report, Jul 12, 1:27 AM EDT, 45 minutes before
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
127 AM EDT FRI JUL 12 2013

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1042 PM     FLASH FLOOD      2 SSW IVY               38.03N  78.61W
07/11/2013                   ALBEMARLE          VA   911 CALL CENTER

            ROAD CLOSED DUE TO FLASH FLOODING AT 3600 BLOCK OF DICK
            WOODS RD

&&

EVENT NUMBER LWX1300622

JRK
Local storm report, Jul 12, 1:31 AM EDT, 41 minutes before
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Local storm report, Jul 12, 1:32 AM EDT, 40 minutes before
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Local storm report, Jul 12, 1:34 AM EDT, 38 minutes before
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Local storm report, Jul 12, 1:50 AM EDT, 22 minutes before
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Local storm report, Jul 12, 2:05 AM EDT, 7 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
Jul 11, 9:35 PM EDTFlash Flood WarningLWXAlbemarle, City of Charlottesville3 hr
Jul 11, 10:39 PM EDTFlash Flood WarningLWXFairfax, Loudoun, Prince William3 hr
Jul 11, 10:47 PM EDTFlash Flood WarningLWXPage, Rockingham, City of Harrisonburg3 hr
Jul 11, 11:12 PM EDTFlash Flood WarningLWXCulpeper, Fauquier, Greene, Madison, Page, Prince William and 2 more6 hr
Jul 11, 11:26 PM EDTFlash Flood WarningLWXFairfax5 hr
Jul 12, 12:14 AM EDTFlash Flood WarningLWXArlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church3 hr
Jul 12, 12:28 AM EDTAreal Flood WarningLWXAlbemarle, City of Charlottesville13 hr
Jul 12, 1:05 AM EDTFlash Flood WarningLWXFairfax, Fauquier, Prince William, City of Manassas, City of Manassas Park4 hr
Jul 12, 1:33 AM EDTAreal Flood WarningLWXPage, Rockingham, City of Harrisonburg13 hr
Jul 12, 1:44 AM EDTAreal Flood WarningLWXFairfax, Loudoun, Prince William14 hr
Jul 12, 2:31 AM EDTSpecial Marine WarningLWX89 min
Jul 12, 3:08 AM EDTFlash Flood WarningLWXArlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church3 hr
Jul 12, 3:12 AM EDTSpecial Marine WarningLWX2 hr
Jul 12, 3:44 AM EDTSpecial Marine WarningLWX91 min
Jul 12, 3:46 AM EDTFlash Flood WatchLWXArlington, Clarke, Culpeper, Fairfax, Fauquier, Frederick and 21 more14 hr
Jul 12, 4:25 AM EDTAreal Flood WarningLWXRockingham11 hr
Jul 12, 4:58 AM EDTAreal Flood WarningLWXCulpeper, Fauquier, Greene, Madison, Page, Prince William and 2 more23 hr
Jul 12, 5:13 AM EDTAreal Flood WarningLWXFairfax, Fauquier, Prince William, City of Manassas, City of Manassas Park23 hr
Jul 12, 5:18 AM EDTSpecial Marine WarningLWX117 min
Jul 12, 5:47 AM EDTAreal Flood WarningLWXArlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church14 hr
Jul 12, 6:08 AM EDTAreal Flood WarningLWXCulpeper, Greene, Madison, Orange8 hr
Jul 12, 8:12 AM EDTRiver Flood WarningLWXRockingham13 hr
Jul 12, 8:12 AM EDTRiver Flood WarningLWXCulpeper, Fauquier19 hr
Jul 12, 9:17 AM EDTRiver Flood WarningLWXClarke12 hr
Jul 12, 9:28 AM EDTSmall Craft AdvisoryLWX13 hr
Jul 12, 12:13 PM EDTAreal Flood WarningLWXShenandoah9 hr
Jul 12, 3:28 AM EDTFlash Flood WarningLWXCharles, Prince George's4 hr
Jul 12, 4:24 AM EDTFlash Flood WarningLWXAnne Arundel, Prince George's4 hr
Jul 12, 4:30 AM EDTAreal Flood WarningLWXMontgomery4 hr
Jul 11, 9:39 PM EDTFlash Flood WarningLWXGrant, Hardy, Pendleton3 hr

Nearby

Flash Flood Warnings in Virginia, 2013Every flash flood warning in 2013

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.