Alert archive / West Virginia / Mesoscale Discussions in 2020

Mesoscale Discussion 321

April 9, 202013 counties in Virginia; 14 counties in West Virginia

The Storm Prediction Center issued this mesoscale discussion at Apr 9, 2020, 12:50 AM EDT for 13 counties in Virginia; 14 counties in West Virginia. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued
Apr 9, 2020, 12:50 AM EDT (04:50 UTC)
Expired
Apr 9, 2020, 2:45 AM EDT
In force
115 min
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 27 counties

Alleghany County, VA, Bath County, VA, Bland County, VA, City of Covington, VA, City of Radford, VA, Craig County, VA, Giles County, VA, Highland County, VA, Montgomery County, VA, Pulaski County, VA, Roanoke County, VA, Tazewell County, VA, Wythe County, VA, Barbour County, WV, Doddridge County, WV, Greenbrier County, WV, Harrison County, WV, Lewis County, WV, Mercer County, WV, Monroe County, WV, Pendleton County, WV, Pocahontas County, WV, Randolph County, WV, Summers County, WV, Tucker County, WV, Upshur County, WV, Webster County, WV

The radar

The Charleston,WV radar (KRLX), 99 km from the middle of the area, began a volume at 04:52 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Roanoke, VA (KRNK), launched 00:00Z, 4.8 hours before the alert went out and 153 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 00:00Z on 2020-04-09Temperature 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 00:00Z on 2020-04-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 145 square meters per square second.1939587897117136Sfc1 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
1382 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
145 m²/s²
0-3 km storm-relative helicity
268 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 8, 10:14 PM EDTMesoscale DiscussionSPCBuchanan, Dickenson, Wise, City of Norton3 hr
Apr 8, 10:51 PM EDTTornado WatchSPCBuchanan, Dickenson5 hr
Apr 8, 11:16 PM EDTSevere Thunderstorm WatchSPCLee, Russell, Scott, Washington, Wise, City of Bristol and 1 more6 hr
Apr 9, 2:03 AM EDTSevere Thunderstorm WatchSPCAlbemarle, Alleghany, Amherst, Augusta, Bath, Bedford and 37 more3 hr
Apr 9, 3:36 AM EDTMesoscale DiscussionSPCAlbemarle, Alleghany, Amherst, Augusta, Bath, Bedford and 40 more84 min
Apr 9, 12:01 PM EDTSevere Thunderstorm WatchSPCArlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church4 hr

Nearby

Mesoscale Discussions in West Virginia, 2020Mesoscale Discussions in Virginia, 2020Every 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.