Alert archive / Virginia / Severe Thunderstorm Warnings in 2007

Severe Thunderstorm Warning 235, NWS Blacksburg, VA

July 27, 2007Montgomery County, City of Radford, Virginia

NWS Blacksburg, VA issued this severe thunderstorm warning at Jul 27, 2007, 1:26 PM EDT for Montgomery County, City of Radford, Virginia. It was in force for 55 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 27, 2007, 1:26 PM EDT (17:26 UTC)
Expired: Jul 27, 2007, 2:21 PM EDT
In force: 55 min
Issued by: NWS Blacksburg, VA
Area: Counties, with a storm outline in the text

Counties City of Radford, VA, Montgomery County, VA

The radar

The Roanoke radar (KFCX), 23 km from the middle of the area, began a volume at 17:28 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 27, 1:26 PM EDT	Severe Thunderstorm Watch	SPC	6 hr

The nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 5.4 hours before the alert went out and 87 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: 1044 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 758 m above ground
0-6 km bulk shear: 19 kt
0-1 km storm-relative helicity: 74 m²/s²
0-3 km storm-relative helicity: 72 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 Blacksburg, VA wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 27, 10:21 AM EDT, 3 hours 5 minutes earlier.

Area forecast discussion, Jul 27, 10:21 AM EDT, 3 hours 5 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1021 AM EDT FRI JUL 27 2007

.SYNOPSIS...
A WEAK TROUGH OF LOW PRESSURE WILL MOVE ACROSS THE MOUNTAINS FROM
THE NORTHWEST BY EARLY THIS EVENING. A COLD FRONT WILL ALSO APPROACH
THE REGION FROM THE NORTHWEST SATURDAY BEFORE SLIDING THROUGH THE
AREA ON SUNDAY. THE FRONT WILL THEN STALL OVER THE CAROLINAS INTO
EARLY NEXT WEEK.
&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MAIN CONCERN THIS AFTERNOON WITH OLD UPSTREAM CONVECTIVE COMPLEX
SHIFTING SE FROM THE OHIO VALLEY REGION IN ADVANCE OF MIDWEST COLD
FRONT. LATEST MODIFIED 12Z RAOBS SHOW 2K CAPES OR BETTER PROVIDED
HEATING THRU DEBRIS CLOUDS AS OLD MCV/TROF PUSH TOWARD THE
APPALACHIANS. MID LEVEL JET ASSOCIATED WITH THIS AREA OF LIFT
LIKELY TO MAKE FOR STRONG WIND CONCERNS IF CONVECTION ORGANIZES AS
WINDEX VALUES QUITE STRONG. OTRW 12Z NAM SEEMS TO HAVE A BETTER
HANDLE ON CURRENT TSRA AND IN TURN PUSHES BAND OF CONVECTION INTO
THE WESTERN SLOPES TOWARD 18Z. THINK AHEAD OF THIS FEATURE WILL
ALSO SEE DIFF HEATING AID ISOLATED COVERAGE BLUE RIDGE AND
POSSIBLY OUT EAST LATER ON WITH LEE TROF. THIS SIMILAR TO THE WRF-
ARW WHICH ACTUALLY HAS BEST LIFT TO THE NORTH WITH PREFRONTAL S/W
AXIS WHILE THE RUC A BIT FARTHER SOUTH ALONG THE WESTERN SLOPES.
THUS WILL SPEED UP POPS FOR THE AFTERNOON WESTERN ZONES AND
INCREASE TO HIGH CHANCE WEST/MID RANGE CHANCE FARTHER EAST.
MORNING THICKNESS VALUES SUPPORT AROUND 90 FOR HIGHS PIEDMONT BUT
A LITTLE COOLER MOUNTAINS WHERE CLOUDS SHOULD HOLD VALUES CLOSER
TO THE LAV DEPICTED 80-85 SCENARIO.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
MODELS OPEN UP LOW LATE TONIGHT. WAVE OUT OF IA COMES ACROSS LATE
TONIGHT AND SATURDAY MORNING.

SUNDAY NIGHT CHANNELED VORTICITY. DEEP MOISTURE AND QPF IS OVER THE
SOUTHERN COUNTY WARNING AREA. THERE ARE WARMER TEMPERATURES AT 500
MB SATURDAY AND SUNDAY.

THROUGH SUNDAY AIRMASS REMAINS MOIST WITH PRECIPITABLE WATER AROUND
1.5 INCHES AND ENOUGH INSTABILITY EACH AFTERNOON AND EVENING FOR
SCATTERED THUNDERSTORMS...GIVEN EVEN A WEAK TRIGGER. THE SURFACE
COLD FRONT COMES THROUGH THE COUNTY WARNING AREA BETWEEN 18Z SUNDAY
AND 06Z MONDAY.

LOW LEVEL WINDS BACK TO THE SOUTH ON SATURDAY WITH THE APPROACH OF
THE 850 MB LOW AND MODELS GFS ALSO SHOWING A 40 KNOT 850 MB JET
DURING THE DAY.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
UNSETTLED WEATHER WILL CONTINUE IN THE MEDIUM RANGE. FOLLOWED
HPCGUIDE FOR EXTENDED PERIOD WHICH WAS A BLEND OF 00Z ECMWF AND
NCEP-GEF ENSEMBLE MEAN. HIGH PRESSURE MOVES ACROSS EASTERN CANADA
THIS WEEKEND...AND WEAKENS UPPER LEVEL LOW AS IT BECOMES ABSORBED
INTO EASTERN TROF. THE COLD FRONT STALL ACROSS SOUTHEAST U.S. ON
MONDAY INTO WEDNESDAY...AS SURFACE WAVES MOVE NORTHEAST ALONG THE
BOUNDARY.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
EXPECT THE VISIBILITY AT LWB TO CONTINUE DROPPING THROUGH 12Z TO
LIFR VALUES. HAZE AND FOG AT TAF SITES WILL MIX OUT THIS MORNING.
THEN CONDITIONS WILL BE VRF UNTIL MID AFTERNOON.

MODELS BRING SCATTERED THUNDERSTORMS INTO THE MOUNTAINS AROUND
19Z...WITH LESS COVERAGE IN THE PIEDMONT AFTER 22Z. CEILINGS AND
VISIBILITIES WILL BE MVFR WITH ANY OF THE STORMS.

SURFACE DEW POINTS WILL GRADUALLY INCREASE OVER THE NEXT 24 HOURS.
LIGHT WINDS OVERNIGHT COMBINED WITH THIS LOW LEVEL MOISTURE WILL
RESULT IN MVFR FOG ACROSS THE REGION LATE TONIGHT. LWB IS AGAIN
EXPECTED TO DROP TO LIFR LEVELS.

FRIDAY NIGHT AND SATURDAY A STRONG SHORT WAVE BRINGS A LOW FROM
THE UPPER MISSISSIPPI VALLEY INTO VIRGINA. WIDESPREAD SHOWERS AND
THUNDERSTORMS ARE LIKELY IN THE MOUNTAINS...RESULTING IN MVFR
CONDITIONS.

A COLD FRONT CROSSES THROUGH THE FORECAST AREA SUNDAY NIGHT. THIS
SHOULD BRING A BREAK TO THE CYCLE OF MORNING FOG/AFTERNOON AND
EVENING THUNDERSTORMS.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.

&&

SYNOPSIS...JH
NEAR TERM...JH
SHORT TERM...AMS
LONG TERM...KK
AVIATION...AMS/KM

Hazardous weather outlook, Jul 27, 11:30 AM EDT, 1 hour 56 minutes before

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In the hours before

Special weather statement, Jul 27, 1:10 PM EDT, 16 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BLACKSBURG VA
110 PM EDT FRI JUL 27 2007

VAZ016-017-032-271745-
PATRICK VA-FLOYD VA-CARROLL VA-
110 PM EDT FRI JUL 27 2007

AT 108 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 7 MILES EAST OF HILLSVILLE...OR ABOUT 3 MILES
SOUTH OF DUGSPUR...MOVING EAST AT 20 MPH. THE STRONG THUNDERSTORM
WILL BE NEAR...LAUREL FORK AT 120 PM EDT...WILLIS AT 125 PM EDT...
MEADOWS OF DAN AT 135 PM EDT...MABRY MILL AT 140 PM EDT...ROCKY KNOB
RECREATION AREA...ROCKY KNOB SUMMIT AT 145 PM EDT.

EXPECT SMALL HAIL...FREQUENT LIGHTNING...AND WIND GUSTS TO 50 MPH
WITH THIS STORM.  IF THE STORM CONTINUES TO INTENSIFY A SEVERE
THUNDERSTORM WARNING MAY BE NEEDED.

THE PUBLIC IS ENCOURAGED TO RELAY REPORTS OF STRONG WINDS...HAIL OR
FLOODING TO THE NATIONAL WEATHER SERVICE IN BLACKSBURG BY CALLING
1...8 6 6...2 1 5...4 3 2 4.

SK

The office that day

Everything else NWS Blacksburg, VA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 26, 11:33 PM EDT	Severe Thunderstorm Warning	RNK	Alleghany, Bath, City of Covington	55 min
Jul 27, 1:00 AM EDT	Severe Thunderstorm Warning	RNK	Craig	25 min
Jul 27, 1:37 PM EDT	Severe Thunderstorm Warning	RNK	Giles	48 min
Jul 27, 1:42 PM EDT	Severe Thunderstorm Warning	RNK	Patrick	78 min
Jul 27, 2:40 PM EDT	Severe Thunderstorm Warning	RNK	Roanoke, City of Roanoke, City of Salem	47 min
Jul 27, 2:47 PM EDT	Severe Thunderstorm Warning	RNK	Franklin	58 min
Jul 27, 3:29 PM EDT	Severe Thunderstorm Warning	RNK	Bedford	76 min
Jul 27, 4:37 PM EDT	Severe Thunderstorm Warning	RNK	Pittsylvania, City of Danville	38 min
Jul 27, 4:42 PM EDT	Severe Thunderstorm Warning	RNK	Bath	63 min
Jul 27, 4:50 PM EDT	Severe Thunderstorm Warning	RNK	Halifax	69 min
Jul 27, 5:01 PM EDT	Severe Thunderstorm Warning	RNK	Campbell, Charlotte	62 min
Jul 27, 4:56 PM EDT	Severe Thunderstorm Warning	RNK	Surry	52 min
Jul 27, 5:13 PM EDT	Severe Thunderstorm Warning	RNK	Caswell	31 min
Jul 26, 10:39 PM EDT	Severe Thunderstorm Warning	RNK	Greenbrier	81 min
Jul 26, 10:47 PM EDT	Severe Thunderstorm Warning	RNK	Summers	73 min
Jul 26, 11:01 PM EDT	Severe Thunderstorm Warning	RNK	Mercer	37 min

Nearby

Severe Thunderstorm Warnings in Virginia, 2007 Every severe thunderstorm warning in 2007

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.