Alert archive / West Virginia / Mesoscale Discussions in 2012

Mesoscale Discussion 1396

July 4, 20124 states

The Storm Prediction Center issued this mesoscale discussion at Jul 4, 2012, 8:05 PM EDT for 4 states. It was in force for 55 min.

The area

The outline as issued.

The facts

Issued
Jul 4, 2012, 8:05 PM EDT (00:05 UTC)
Expired
Jul 4, 2012, 9:00 PM EDT
In force
55 min
Issued by
the Storm Prediction Center
All 22 counties

Allegany County, MD, Garrett County, MD, Washington County, MD, Bedford County, PA, Fayette County, PA, Fulton County, PA, Somerset County, PA, City of Winchester, VA, Clarke County, VA, Frederick County, VA, Loudoun County, VA, Rappahannock County, VA, Shenandoah County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Preston County, WV

The radar

The Sterling radar (KLWX), 120 km from the middle of the area, began a volume at 00:08 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, 0.1 hours before the alert went out and 128 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 2012-07-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2993 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 2012-07-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 27 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
2993 J/kg
Mixed-layer CIN
-17 J/kg
Mixed-layer LCL
1701 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
27 m²/s²
0-3 km storm-relative helicity
107 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.

646 
ACUS11 KWNS 050006
SWOMCD
SPC MCD 050005
MDZ000-VAZ000-PAZ000-WVZ000-050100-

MESOSCALE DISCUSSION 1396
NWS STORM PREDICTION CENTER NORMAN OK
0705 PM CDT WED JUL 04 2012

AREAS AFFECTED...SWRN PA...NRN WV...MD PANHANDLE...NRN VA

CONCERNING...SEVERE THUNDERSTORM WATCH 461...

VALID 050005Z - 050100Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 461
CONTINUES.

SUMMARY...DMMG WIND/HAIL THREAT IS CONFINED TO FAR ERN PORTIONS OF
WW 461...AND E OF WW 461 INTO THE MD PANHANDLE AND NRN VA. A NEW WW
IS NOT ANTICIPATED ATTM...BUT CONVECTIVE TRENDS WILL BE MONITORED.

DISCUSSION...LATEST RADAR LOOP SHOWS CLUSTER OF TSTMS MOVING OUT OF
SWRN PA/ERN WV SEWD INTO PORTIONS OF THE MD PANHANDLE AND NRN
VA...CONSOLIDATING WITH A STRONGER AND INITIALLY DISCRETE STORM OVER
GARRETT COUNTY MD. EXTRAPOLATION OF ONGOING CONVECTION AND NELY
BACKGROUND FLOW SAMPLED AT 10-20 KTS PER LWX/PBZ VWP DATA WILL FAVOR
CONTINUED PROPAGATION TOWARDS THE SE. ALTHOUGH INSTABILITY WILL
SLOWLY DECREASE DUE TO BOUNDARY LAYER COOLING...RICH LOW-LEVEL
MOISTURE /SFC DEW POINTS IN THE UPPER 60S-LOWER 70S/ WILL MAINTAIN
MLCAPE VALUES NEAR 2000 J/KG. MORE RECENT RADAR TRENDS HAVE SHOWED A
GRADUAL WEAKENING OF TSTMS...BUT GIVEN SUPPORTIVE DOWNSTREAM
ENVIRONMENT...A DMGG WIND AND MARGINALLY SVR HAIL THREAT COULD
PERSIST FOR THE NEXT FEW HRS INTO NRN VA.

..ROGERS/CORFIDI.. 07/05/2012

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

ATTN...WFO...CTP...LWX...PBZ...

LAT...LON   38607823 39107927 39508001 40088001 40277940 40197871
            39987816 39557754 38867767 38607823

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 5, 3:29 AM EDTMesoscale DiscussionSPCCalvert, Charles, Saint Mary's, Somerset91 min
Jul 5, 4:37 PM EDTMesoscale DiscussionSPCAnne Arundel, Baltimore, Carroll, Cecil, Frederick, Harford and 6 more113 min
Jul 4, 9:48 PM EDTMesoscale DiscussionSPCBeaver, Lawrence, Washington87 min
Jul 4, 10:19 PM EDTSevere Thunderstorm WatchSPCAllegheny, Beaver, Butler, Greene, Lawrence, Mercer and 2 more4 hr
Jul 5, 6:16 AM EDTSevere Thunderstorm WatchSPCCrawford, Erie, Lawrence, Mercer3 hr
Jul 5, 11:14 AM EDTMesoscale DiscussionSPCBland, Buchanan, Dickenson, Grayson, Lee, Russell and 9 more91 min
Jul 5, 11:37 AM EDTSevere Thunderstorm WatchSPCBland, Buchanan, Carroll, Craig, Dickenson, Floyd and 20 more7 hr
Jul 5, 1:40 PM EDTMesoscale DiscussionSPCBrunswick, Charles City, Dinwiddie, Greensville, Henrico, Isle of Wight and 13 more95 min
Jul 5, 2:57 PM EDTMesoscale DiscussionSPCAlleghany, Bland, Botetourt, Buchanan, Carroll, Craig and 23 more2 hr
Jul 5, 8:00 AM EDTMesoscale DiscussionSPCBrooke, Doddridge, Hancock, Marshall, Ohio, Pleasants and 4 more90 min

Nearby

Mesoscale Discussions in West Virginia, 2012Mesoscale Discussions in Virginia, 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.