Alert archive / Virginia / Mesoscale Discussions in 2021

Mesoscale Discussion 72

February 13, 202124 counties in North Carolina; 62 counties in Virginia

The Storm Prediction Center issued this mesoscale discussion at Feb 13, 2021, 2:21 AM EST for 24 counties in North Carolina; 62 counties in Virginia. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued
Feb 13, 2021, 2:21 AM EST (07:21 UTC)
Expired
Feb 13, 2021, 8:15 AM EST
In force
6 hr
Issued by
the Storm Prediction Center
Concerning
Freezing rain
All 86 counties

Alamance County, NC, Alleghany County, NC, Ashe County, NC, Caswell County, NC, Davidson County, NC, Davie County, NC, Durham County, NC, Forsyth County, NC, Franklin County, NC, Granville County, NC, Guilford County, NC, Halifax County, NC, Nash County, NC, Northampton County, NC, Orange County, NC, Person County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Wilkes County, NC, Yadkin County, NC, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Buena Vista, VA, City of Colonial Heights, VA, City of Danville, VA, City of Emporia, VA, City of Franklin, VA, City of Galax, VA, City of Hopewell, 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 Williamsburg, VA, Craig County, VA, Cumberland County, VA, Dinwiddie County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Gloucester County, VA, Goochland County, VA, Grayson County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, James City County, VA, King and Queen County, VA, King William County, VA, Lunenburg County, VA, Mecklenburg County, VA, Middlesex County, VA, Montgomery County, VA, New Kent County, VA, Nottoway County, VA, Patrick County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Pulaski County, VA, Roanoke County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, Wythe County, VA

The nearest sounding before it

Roanoke, VA (KRNK), launched 00:00Z, 7.4 hours before the alert went out and 64 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 2021-02-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCLEL10008507005003002001001 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 2021-02-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 5 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
484 m above ground
0-6 km bulk shear
61 kt
0-1 km storm-relative helicity
5 m²/s²
0-3 km storm-relative helicity
101 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

626 
ACUS11 KWNS 130721
SWOMCD
SPC MCD 130721 
VAZ000-NCZ000-WVZ000-131315-

Mesoscale Discussion 0072
NWS Storm Prediction Center Norman OK
0121 AM CST Sat Feb 13 2021

Areas affected...northern North Carolina...southern half of Virginia

Concerning...Freezing rain 

Valid 130721Z - 131315Z

SUMMARY...Freezing rain is forecast to increase in coverage with
precipitation rates around 0.05 inch per 3 hours, especially over
northern North Carolina and far southern Virginia.

DISCUSSION...Radar mosaic tonight shows a shield of light
precipitation from the western Carolinas northeast into southern
Virginia.  Surface observations over northern North Carolina have
indicated mainly light freezing rain rates.  Weak warm advection
within a layer of above-freezing air is contributing to lift
supporting precipitation into a sub-freezing surface layer.  A
gradual increase in freezing rain, both in coverage and rates, is
expected especially towards the early morning hours.  Both SREF and
HREF model guidance indicate a northward progression of
precipitation later tonight into the early morning.  Model forecast
soundings suggest columnar saturation over the northern and western
fringe of the discussion area over the next few hours.  This
expansion in precipitation will translate to freezing rain
developing from the greater Blacksburg vicinity, eastward into
central portions of Virginia, during the 5am-8am EST period.

..Smith.. 02/13/2021

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

ATTN...WFO...AKQ...LWX...RAH...RNK...GSP...

LAT...LON   36178171 37038135 37698024 37837727 37727657 37357643
            36597698 35967793 35737880 35738021 36038163 36178171

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Feb 13, 10:02 AM ESTMesoscale DiscussionSPCAlbemarle, Amelia, Amherst, Appomattox, Arlington, Augusta and 64 more6 hr

Nearby

Mesoscale Discussions in Virginia, 2021Mesoscale Discussions in North Carolina, 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.