Alert archive / Virginia / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 301, NWS Baltimore/Washington

July 13, 2011Albemarle County, Orange County, Spotsylvania County, Virginia

NWS Baltimore/Washington issued this severe thunderstorm warning at Jul 13, 2011, 5:08 PM EDT for Albemarle County, Orange County, Spotsylvania County, Virginia. It was in force for 52 min. 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 13, 2011, 5:08 PM EDT (21:08 UTC)
Expired: Jul 13, 2011, 6:00 PM EDT
In force: 52 min
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon

Counties Albemarle County, VA, Orange County, VA, Spotsylvania County, VA

The radar

The Sterling radar (KLWX), 105 km from the middle of the area, began a volume at 21:10 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 13, 2:21 PM EDT	Severe Thunderstorm Watch	SPC	8 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 9.1 hours before the alert went out and 106 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 43 J/kg
Mixed-layer CIN: -229 J/kg
Mixed-layer LCL: 1399 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: -33 m²/s²
0-3 km storm-relative helicity: 4 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm 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 severe thunderstorm warning went out at Jul 13, 4:07 PM EDT, 1 hour 1 minute earlier.

Area forecast discussion, Jul 13, 4:07 PM EDT, 1 hour 1 minute before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
407 PM EDT WED JUL 13 2011

.SYNOPSIS...
HIGH PRESSURE DOMINATES MID-ATLANTIC WEATHER THROUGH THE WEEKEND.
LOW PRESSURE MAY IMPACT THE AREA EARLY NEXT WEEK.

&&

.NEAR TERM /TONIGHT/...

WE CONTINUE TO MONITOR RDR/OBS FOR PTNL SVR/FLSH FLDG. WE ARE
DROPPING THE SVR TSTM BEHIND THE LN AS NEEDED. INTERESTING TO SEE
HOW MUCH THE TEMPS HV DROPPED TO THE N OF THE SQUALL LN.

CURRENT RADAR REFLECTIVITY DEPICTS SHOWERS AND THUNDERSTORMS FIRING
IN FRONT OF A COLD FRONT THAT WILL DRIFT OFF THE ATLANTIC SEABOARD
TONIGHT. SATELLITE IMAGERY SHOWS A TROUGH DIGGING TO THE SOUTHEAST
ACROSS THE MIDATLANTIC STATES. THIS SHORTWAVE TROUGH IS PROVIDING
THE PRIMARY TRIGGER FOR CONVECTION THIS AFTERNOON.

12Z SOUNDINGS INDICATE AN ENVIRONMENT...THAT AFTER WARMING THIS
AFTERNOON...HAS CAPE OF AROUND 1200 J/KG. A JET STREAK CURRENTLY
LOCATED JUST TO THE NORTH OF THE CWA IS HELPING TO PROVIDE A FAIR
AMOUNT OF SHEAR. DCAPE MEASUREMENTS FROM A MODIFIED SOUNDING SHOW
THE POTENTIAL FOR DOWN DRAFTS AROUND 60KT. THE PRIMARY THREAT FOR
CONVECTION THIS AFTERNOON WILL BE IN THE FORM OF DAMAGING WINDS.
CONVECTION SHOULD SPREAD TO THE SOUTH AND EAST ACROSS THE CWA
THROUGH 5 PM. THE MAIN SEVERE THREAT WILL BE AREAS FROM THE DC METRO
SOUTH AND EAST OF I-81. THUNDERSTORMS SHOULD LARGELY BE OUT OF THE
AREA BY EARLY EVENING.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
HIGH PRESSURE BUILDS IN BEHIND THE COLD FRONT. SKIES WILL CLEAR
OVERNIGHT AND REMAIN ONLY PARTLY CLOUDY TOMORROW. TEMPERATURES
TOMORROW WILL BE SLIGHTLY BELOW NORMAL WITH HIGHS IN THE MID 80S.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
HIGH PRESSURE BUILDS IN THURSDAY NIGHT AND FRIDAY...THEN REMAINS
OVERHEAD THROUGH SATURDAY NIGHT. THIS WILL LEAD TO A SEVERAL DAY
PERIOD OF BELOW NORMAL TEMPERATURES WITH ATYPICALLY LOW RELATIVE
HUMIDITY. MAXIMA SHUD AVERAGE BELOW 85F WITH MINIMA IN M50S-L60S
OUTSIDE OF URBAN CENTERS.

CWA WILL MOST LIKELY BE PRECIP-FREE THRU MON AS SFC RIDGE DEPARTS TO
THE E AND UPR RIDGE BUILDS OVRHD. HOWEVER...WITH INCRG SLY FLOW AND
RISING H8-5 HEIGHTS...TEMPS AND RH WILL GRADUALLY RISE.

LONGWAVE TROF DIGS INTO NERN CONUS AS UPR RIDGE RETROGRADES INTO
CNTRL PLAINS MON NGT THRU TUE NGT. LEE TROF/TERRAIN FEATURES WARRANT
AT LEAST LOW POPS NWRN AREAS DURG THIS PERIOD...AND SFC BNDRY/CDFNT
MAY BE ABLE TO SLIDE SWD INTO RGN BEFORE END OF XTDD PERIOD.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...

SHOWERS AND THUNDERSTORMS AHEAD OF A COLD FRONT COULD LOWER VSBYS
AT AREA TERMINALS UNTIL EARLY THIS EVENING. STRONG WIND GUSTS IN
SHOWERS AND STORMS ARE POSSIBLE. CIGS WILL HOLD STEADY AROUND 4000
TO 5000 FT UNTIL AROUND MIDNIGHT. BEHIND THE FRONT...HIGH PRESSURE
WILL BUILD OVER THE REGION WITH CLEARING SKIES TOMORROW. AN
INCREASING PRESSURE GRADIENT ASSOCIATED WITH THE FROPA WILL CAUSE
NORTHWEST GUSTS TO 20KT LATE THIS EVENING AND INTO EARLY TOMORROW
MORNING.

HIGH PRESSURE WILL BE DRY/VFR CONDS AND LGT WINDS FOR THE END OF WK
AND THIS WKEND ACRS THE TERMINALS.

&&

.MARINE...
SCA IN EFFECT UNTIL 8 AM THU. THE TIGHT PRESSURE GRADIENT
ASSOCIATED WITH THE COLD FRONTAL PASSAGE AND THE HIGH PRESSURE
SYSTEM IN ITS WAKE WILL CAUSE NORTH WIND TO GUSTS ABOVE 18 KT OVER
THE CHESAPEAKE BAY OVERNIGHT.

HIPRES DOMINATES THE WATERS FROM THE END OF THIS WK THRU EARLY NEXT
WEEK. SLY WINDS PREVAIL WITH SPEEDS LIKELY RMNG BELOW SCA THRESHOLDS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 9 AM EDT
     THURSDAY FOR ANZ530>534-537-539>541-543.

&&

UPDATE..WOODY!
PRVS...CJL/SBK

Hazardous weather outlook, Jul 13, 5:03 PM EDT, 5 minutes before

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In the hours before

Local storm report, Jul 13, 3:59 PM EDT, 1 hour 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
359 PM EDT WED JUL 13 2011

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

0335 PM     FLASH FLOOD      1 S DUNN LORING         38.88N  77.22W
07/13/2011                   FAIRFAX            VA   DEPT OF HIGHWAYS

            TWO RAMPS OF INTERSTATE 66 AND CAPITAL BELTWAY
            INTERCHANGE CLOSED DUE TO HIGH WATER.

&&

EVENT NUMBER LWX1101202

SBK

Special weather statement, Jul 13, 4:42 PM EDT, 26 minutes before

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Special weather statement, Jul 13, 4:46 PM EDT, 22 minutes before

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Special weather statement, Jul 13, 4:51 PM EDT, 17 minutes before

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Local storm report, Jul 13, 5:04 PM EDT, 4 minutes before

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Local storm report, Jul 13, 5:07 PM EDT, 1 minute before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 13, 1:38 PM EDT	Special Weather Statement	LWX	Loudoun	37 min
Jul 13, 2:19 PM EDT	Special Weather Statement	LWX	City of Fairfax	26 min
Jul 13, 2:27 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Frederick, City of Winchester	35 min
Jul 13, 2:33 PM EDT	Severe Thunderstorm Warning	LWX	Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church	42 min
Jul 13, 2:37 PM EDT	Special Marine Warning	LWX		83 min
Jul 13, 2:40 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Fauquier, Loudoun, Prince William	50 min
Jul 13, 2:53 PM EDT	Special Weather Statement	LWX	Arlington, Fairfax, Loudoun, City of Alexandria, City of Fairfax, City of Falls Church and 1 more	37 min
Jul 13, 3:07 PM EDT	Flash Flood Warning	LWX	Arlington, Fairfax, Loudoun, Prince William, City of Alexandria, City of Fairfax and 1 more	3 hr
Jul 13, 3:13 PM EDT	Severe Thunderstorm Warning	LWX	Fairfax, Prince William, Stafford, City of Alexandria	47 min
Jul 13, 3:19 PM EDT	Special Marine Warning	LWX		86 min
Jul 13, 3:24 PM EDT	Severe Thunderstorm Warning	LWX	Arlington, Fairfax, Fauquier, Loudoun, Prince William, City of Fairfax and 3 more	41 min
Jul 13, 3:44 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Greene, Madison, Page, Rappahannock	33 min
Jul 13, 3:45 PM EDT	Flash Flood Warning	LWX	Fairfax, Prince William, City of Alexandria, City of Manassas, City of Manassas Park	3 hr
Jul 13, 3:52 PM EDT	Special Marine Warning	LWX		83 min
Jul 13, 3:54 PM EDT	Special Marine Warning	LWX		96 min
Jul 13, 3:55 PM EDT	Special Marine Warning	LWX		95 min
Jul 13, 3:58 PM EDT	Special Weather Statement	LWX	Albemarle	32 min
Jul 13, 4:02 PM EDT	Severe Thunderstorm Warning	LWX	King George	43 min
Jul 13, 4:30 PM EDT	Severe Thunderstorm Warning	LWX	King George	45 min
Jul 13, 4:42 PM EDT	Special Weather Statement	LWX	Orange	33 min
Jul 13, 4:46 PM EDT	Special Weather Statement	LWX	King George, Stafford, City of Fredericksburg	29 min
Jul 13, 4:51 PM EDT	Special Weather Statement	LWX	Albemarle, Greene, City of Charlottesville	24 min
Jul 13, 5:33 PM EDT	Special Weather Statement	LWX	Spotsylvania	27 min
Jul 13, 6:38 PM EDT	Special Weather Statement	LWX	Buckingham	37 min
Jul 13, 1:43 PM EDT	Special Weather Statement	LWX	Frederick	32 min
Jul 13, 2:00 PM EDT	Special Weather Statement	LWX	Montgomery	30 min
Jul 13, 2:16 PM EDT	Special Weather Statement	LWX	Montgomery	29 min

Nearby

Severe Thunderstorm Warnings in Virginia, 2011 Every severe thunderstorm 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.