Alert archive / Virginia / Mesoscale Discussions in 2020

Mesoscale Discussion 913

June 14, 20204 states

The Storm Prediction Center issued this mesoscale discussion at Jun 14, 2020, 12:34 PM EDT for 4 states. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: Jun 14, 2020, 12:34 PM EDT (16:34 UTC)
Expired: Jun 14, 2020, 2:30 PM EDT
In force: 116 min
Issued by: the Storm Prediction Center
Concerning: Severe potential...watch unlikely
Chance of a watch: 20%

All 63 counties

Alleghany County, NC, Ashe County, NC, Avery County, NC, Buncombe County, NC, Burke County, NC, Caldwell County, NC, Graham County, NC, Haywood County, NC, Henderson County, NC, Jackson County, NC, Madison County, NC, McDowell County, NC, Mitchell County, NC, Swain County, NC, Transylvania County, NC, Watauga County, NC, Wilkes County, NC, Yancey County, NC, Blount County, TN, Carter County, TN, Cocke County, TN, Grainger County, TN, Greene County, TN, Hamblen County, TN, Hancock County, TN, Hawkins County, TN, Jefferson County, TN, Johnson County, TN, Knox County, TN, Loudon County, TN, Monroe County, TN, Roane County, TN, Sevier County, TN, Sullivan County, TN, Unicoi County, TN, Washington County, TN, Bland County, VA, Buchanan County, VA, Carroll County, VA, City of Bristol, VA, City of Galax, VA, City of Norton, VA, City of Radford, VA, Dickenson County, VA, Giles County, VA, Grayson County, VA, Lee County, VA, Montgomery County, VA, Pulaski County, VA, Russell County, VA, Scott County, VA, Smyth County, VA, Tazewell County, VA, Washington County, VA, Wise County, VA, Wythe County, VA, Logan County, WV, McDowell County, WV, Mercer County, WV, Monroe County, WV, Raleigh County, WV, Summers County, WV, Wyoming County, WV

The radar

The Knoxville radar (KMRX), 98 km from the middle of the area, began a volume at 16:36 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 4.6 hours before the alert went out and 236 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: 1146 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: -21 m²/s²
0-3 km storm-relative helicity: 24 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

195 
ACUS11 KWNS 141634
SWOMCD
SPC MCD 141634 
WVZ000-VAZ000-NCZ000-TNZ000-KYZ000-SCZ000-141830-

Mesoscale Discussion 0913
NWS Storm Prediction Center Norman OK
1134 AM CDT Sun Jun 14 2020

Areas affected...western Virginia...southern West Virginia...western
North Carolina...eastern Tennessee...and far eastern Kentucky

Concerning...Severe potential...Watch unlikely 

Valid 141634Z - 141830Z

Probability of Watch Issuance...20 percent

SUMMARY...Isolated damaging wind gusts are possible as convection
increases and expands throughout the afternoon.  A WW issuance is
not anticipated for this activity.

DISCUSSION...Surface heating/destabilization along and ahead of an
advancing boundary along western portions of the discussion area has
allowed for development of showers and a few thunderstorms over the
last hour.  These storms are in a continually destabilizing
environment, with 70s/low 80s F surface temperatures resulting in
about 1500 J/kg MUCAPE throughout the discussion area.   Lift
associated with a mid-level wave over Ohio was also encouraging
convective development.  Shear is weak across the discussion area,
suggesting that any convection in the region should be either 1)
short-lived or 2) tied to any potential upscale growth into
forward-propagating clusters along the advancing front.  The
instability and steep low-level lapse rates is enough for isolated
storms to pose a brief damaging-wind threat over the course of the
afternoon.  Isolated instances of hail cannot be completely ruled
out.  The eastern extent of this threat should be limited by
relatively stable conditions east of the Appalachians.

Given the isolated nature of the threat, a WW issuance is not
anticipated.

..Cook/Guyer.. 06/14/2020

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

ATTN...WFO...RNK...RLX...GSP...MRX...JKL...

LAT...LON   37858197 38028144 37838051 37248031 36398085 35618156
            35128255 35298401 35538467 35818471 36238389 36558335
            37198261 37858197

Nearby

Mesoscale Discussions in Virginia, 2020 Mesoscale Discussions in North Carolina, 2020 Mesoscale Discussions in Tennessee, 2020 Every mesoscale discussion in 2020

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.