Alert archive / West Virginia / Mesoscale Discussions in 2021

Mesoscale Discussion 494

May 3, 20215 states

The Storm Prediction Center issued this mesoscale discussion at May 3, 2021, 2:47 PM EDT for 5 states. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued: May 3, 2021, 2:47 PM EDT (18:47 UTC)
Expired: May 3, 2021, 4:45 PM EDT
In force: 118 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 5%

All 63 counties

Boyd County, KY, Garrett County, MD, Athens County, OH, Belmont County, OH, Fairfield County, OH, Gallia County, OH, Guernsey County, OH, Hocking County, OH, Jackson County, OH, Lawrence County, OH, Meigs County, OH, Monroe County, OH, Morgan County, OH, Muskingum County, OH, Noble County, OH, Perry County, OH, Vinton County, OH, Washington County, OH, Fayette County, PA, Greene County, PA, Washington County, PA, Barbour County, WV, Boone County, WV, Braxton County, WV, Brooke County, WV, Cabell County, WV, Calhoun County, WV, Clay County, WV, Doddridge County, WV, Fayette County, WV, Gilmer County, WV, Grant County, WV, Harrison County, WV, Jackson County, WV, Kanawha County, WV, Lewis County, WV, Lincoln County, WV, Logan County, WV, Marion County, WV, Marshall County, WV, Mason County, WV, Mineral County, WV, Monongalia County, WV, Nicholas County, WV, Ohio County, WV, Pendleton County, WV, Pleasants County, WV, Pocahontas County, WV, Preston County, WV, Putnam County, WV, Raleigh County, WV, Randolph County, WV, Ritchie County, WV, Roane County, WV, Taylor County, WV, Tucker County, WV, Tyler County, WV, Upshur County, WV, Wayne County, WV, Webster County, WV, Wetzel County, WV, Wirt County, WV, Wood County, WV

The radar

The Charleston,WV radar (KRLX), 112 km from the middle of the area, began a volume at 18:49 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

Pittsburgh, PA (KPIT), launched 12:00Z, 6.8 hours before the alert went out and 167 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 584 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 172 m²/s²
0-3 km storm-relative helicity: 185 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

617 
ACUS11 KWNS 031847
SWOMCD
SPC MCD 031847 
MDZ000-WVZ000-PAZ000-VAZ000-OHZ000-KYZ000-032045-

Mesoscale Discussion 0494
NWS Storm Prediction Center Norman OK
0147 PM CDT Mon May 03 2021

Areas affected...portions of southern and eastern Ohio into West
Virginia and southwestern Pennsylvania

Concerning...Severe potential...Watch unlikely 

Valid 031847Z - 032045Z

Probability of Watch Issuance...5 percent

SUMMARY...A couple of the stronger storms may pose a localized
severe risk through the afternoon hours. A damaging gust or two are
possible and a brief tornado cannot be completely ruled out. Given
the sparse nature of the severe threat, a WW issuance is not
anticipated.

DISCUSSION...Convection has gradually deepened and become more
widespread across portions of the Ohio Valley as a mid-level vort
max traverses the region. Pockets of insolation have allowed for
marginal destabilization of the boundary layer, with around 250-400
J/kg MLCAPE currently realized (per latest Mesoanalysis). 18Z PBZ
and RLX VWPs depict considerable veering of the sfc-500 m winds,
with modest 0-3km speed shear all contributing to 150-300 m2/s2
0-3km SRH, with 0-1km SRH values occasionally exceeding 200 m2/s2.
Nonetheless, upper support is expected to remain modest, with low
and mid-level lapse rates likely to remain below 6.5 C/km across
most locations. While the favorable shear environment would support
a damaging gust or a brief tornado with a stronger storm, the
marginal instability is expected to limit the severe threat. Given
the very sparse and brief nature of any severe threat that can
materialize, a WW issuance is not expected.

..Squitieri/Grams.. 05/03/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CTP...LWX...RNK...PBZ...RLX...ILN...

LAT...LON   37708096 37778204 38238268 38888291 39688282 40028207
            40408067 40217973 39987920 39587884 39167880 38657930
            38128004 37708096

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 3, 7:16 PM EDT	Mesoscale Discussion	SPC	Baltimore, Carroll, Frederick, Harford, Howard, Kent and 1 more	29 min

Nearby

Mesoscale Discussions in West Virginia, 2021 Mesoscale Discussions in Ohio, 2021 Mesoscale Discussions in Pennsylvania, 2021 Every mesoscale discussion in 2021

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.