Alert archive / Virginia / Mesoscale Discussions in 2021
Mesoscale Discussion 49
The Storm Prediction Center issued this mesoscale discussion at Jan 31, 2021, 5:12 AM EST for 68 counties in Virginia; 10 counties in West Virginia. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 31, 2021, 5:12 AM EST (10:12 UTC)
- Expired
- Jan 31, 2021, 11:15 AM EST
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Winter mixed precipitation
All 78 counties
Albemarle County, VA, Alleghany County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Carroll County, VA, Charlotte County, VA, Chesterfield County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Colonial Heights, VA, City of Covington, VA, City of Fredericksburg, VA, City of Galax, VA, City of Harrisonburg, VA, City of Hopewell, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Radford, VA, City of Richmond, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, Craig County, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Giles County, VA, Goochland County, VA, Greene County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Highland County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Montgomery County, VA, Nelson County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Pulaski County, VA, Rappahannock County, VA, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Spotsylvania County, VA, Stafford County, VA, Wythe County, VA, Fayette County, WV, Greenbrier County, WV, Mercer County, WV, Monroe County, WV, Nicholas County, WV, Pendleton County, WV, Pocahontas County, WV, Raleigh County, WV, Summers County, WV, Webster County, WV
The radar
The Roanoke radar (KFCX), 117 km from the middle of the area, began a volume at 10:15 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 00:00Z, 10.2 hours before the alert went out and 67 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1348 m above ground
- 0-6 km bulk shear
- 56 kt
- 0-1 km storm-relative helicity
- 178 m²/s²
- 0-3 km storm-relative helicity
- 209 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
189
ACUS11 KWNS 311012
SWOMCD
SPC MCD 311012
VAZ000-WVZ000-311615-
Mesoscale Discussion 0049
NWS Storm Prediction Center Norman OK
0412 AM CST Sun Jan 31 2021
Areas affected...Virginia...Southeast West Virginia...
Concerning...Winter mixed precipitation
Valid 311012Z - 311615Z
SUMMARY...Heavy snow will likely develop across parts of southeast
West Virginia and Virginia this morning. A mixture of freezing rain,
sleet and snow will be likely across parts of far southern West
Virginia and southern Virginia this morning.
DISCUSSION...Mosaic radar imagery currently shows a band of moderate
to heavy precipitation spreading east-northeastward across parts of
the southern Appalachians. This band is being supported by a
shortwave trough evident on water vapor imagery. In advance of the
shortwave trough, warm advection and isentropic lift is maximized
across parts of the southern Appalachians according to short-term
model solutions. This area of strong lift is forecast to move
eastward across Virginia this morning. Temperatures are now below
freezing across most of Virginia with profiles supporting snow
across the northern two-thirds of the state. In response, a band of
moderate to heavy snowfall with maximized rates in the 1 to 1.5
inches per hour range, is expected to develop over the next 2 to 4
hours in a corridor about 100 statute miles wide, from near Beckley,
West Virginia eastward to near Lynchburg, Virginia. This band of
moderate to heavy snowfall could affect areas as far east as
Richmond, Virginia later this morning.
Further to the south, forecast soundings suggest a warm layer is
present near 850 mb. This warm layer will keep precipitation in a
mixed state with freezing rain, sleet and snow all possible this
morning. The corridor with the greatest potential for mixed
precipitation is forecast to be south of Blacksburg and Roanoke to
near the Virginia state-line.
..Broyles.. 01/31/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...LWX...RNK...RLX...
LAT...LON 38747912 38648017 38498075 38188104 37538142 37028152
36778148 36668130 36638082 36657921 36817762 37347717
37927707 38277716 38487741 38677781 38737841 38747912Nearby
Mesoscale Discussions in Virginia, 2021Mesoscale Discussions in West Virginia, 2021Every 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.