Alert archive / West Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 2076

October 18, 2012Pike County, Kentucky; Greene County, Pennsylvania; 25 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Oct 18, 2012, 3:07 PM EDT for Pike County, Kentucky; Greene County, Pennsylvania; 25 counties in West Virginia. It was in force for 83 min.

The area

The outline as issued.

The facts

Issued
Oct 18, 2012, 3:07 PM EDT (19:07 UTC)
Expired
Oct 18, 2012, 4:30 PM EDT
In force
83 min
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 27 counties

Pike County, KY, Greene County, PA, Barbour County, WV, Boone County, WV, Braxton County, WV, Calhoun County, WV, Clay County, WV, Doddridge County, WV, Fayette County, WV, Gilmer County, WV, Harrison County, WV, Kanawha County, WV, Lewis County, WV, Logan County, WV, Marion County, WV, McDowell County, WV, Mingo County, WV, Monongalia County, WV, Nicholas County, WV, Preston County, WV, Raleigh County, WV, Randolph County, WV, Taylor County, WV, Upshur County, WV, Webster County, WV, Wetzel County, WV, Wyoming County, WV

The radar

The Charleston,WV radar (KRLX), 59 km from the middle of the area, began a volume at 19:10 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 nearest sounding before it

Roanoke, VA (KRNK), launched 12:00Z, 7.1 hours before the alert went out and 197 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, Roanoke, VA at 12:00Z on 2012-10-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Roanoke, VA at 12:00Z on 2012-10-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 222 square meters per square second.1939587897Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
671 m above ground
0-6 km bulk shear
44 kt
0-1 km storm-relative helicity
222 m²/s²
0-3 km storm-relative helicity
233 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.

870 
ACUS11 KWNS 181907
SWOMCD
SPC MCD 181907 
MDZ000-WVZ000-PAZ000-VAZ000-KYZ000-182030-

MESOSCALE DISCUSSION 2076
NWS STORM PREDICTION CENTER NORMAN OK
0207 PM CDT THU OCT 18 2012

AREAS AFFECTED...CNTRL APPALACHIANS

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 181907Z - 182030Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLATED STRONG/SEVERE THUNDERSTORMS WILL SPREAD/DEVELOP
ACROSS PORTIONS OF THE CENTRAL APPALACHIANS THROUGH THE MID-LATE
AFTERNOON HOURS.

DISCUSSION...A NARROW CORRIDOR OF STEEP LOW LEVEL LAPSE RATES HAS
DEVELOPED AHEAD OF ADVANCING COLD FRONT FROM WRN VA...NWD ACROSS WV
INTO EXTREME SWRN PA.  PARTIAL BREAKS IN CLOUD COVER HAVE ALLOWED
SFC TEMPERATURES TO WARM INTO THE LOWER-MID 70S ALONG THIS AXIS
WHICH IS COINCIDENT WITH LEADING EDGE OF MOISTURE SURGE ALONG WEST
SLOPES OF THE HIGHER TERRAIN.  AS A RESULT A FEW ROBUST
THUNDERSTORMS HAVE EVOLVED...A FEW EXHIBITING WEAK
ROTATION/SUPERCELL CHARACTERISTICS.  ALTHOUGH STRONG DEEP LAYER
SHEAR WOULD OTHERWISE SUGGEST ORGANIZED LONGER LIVED
UPDRAFTS...CURRENT THINKING IS NARROW/WEAK CORRIDOR OF INSTABILITY
WILL LIMIT SEVERITY OF THIS ACTIVITY...THOUGH HAIL MAY APPROACH
SEVERE LEVELS AND GUSTY WINDS MAY ACCOMPANY THE STRONGEST STORMS.

..DARROW/THOMPSON.. 10/18/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...RNK...PBZ...RLX...JKL...

LAT...LON   37488255 38758130 39958039 39747940 38607991 37228144
            37488255

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Oct 17, 8:35 PM EDTMesoscale DiscussionSPCBallard, Carlisle, Fulton, Hickman85 min
Oct 17, 8:47 PM EDTSevere Thunderstorm WatchSPCCaldwell, Calloway, Christian, Crittenden, Daviess, Henderson and 10 more75 min
Oct 17, 9:07 PM EDTMesoscale DiscussionSPCCalloway53 min

Nearby

Mesoscale Discussions in West Virginia, 2012Mesoscale Discussions in Kentucky, 2012Mesoscale Discussions in Pennsylvania, 2012Every mesoscale discussion 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.