Mesoscale Discussion 309

Issued

Mar 31, 2021, 2:22 PM EDT (18:22 UTC)

Expired

Mar 31, 2021, 4:15 PM EDT

In force

113 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch possible

Chance of a watch

40%

The Raleigh/Durham radar (KRAX), 62 km from the middle of the area, began a volume at 18:21 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.

298 
ACUS11 KWNS 311823
SWOMCD
SPC MCD 311822 
NCZ000-VAZ000-SCZ000-312015-

Mesoscale Discussion 0309
NWS Storm Prediction Center Norman OK
0122 PM CDT Wed Mar 31 2021

Areas affected...Portions of South/North Carolina into southeast
Virginia

Concerning...Severe potential...Watch possible 

Valid 311822Z - 312015Z

Probability of Watch Issuance...40 percent

SUMMARY...Strong to severe storms along a cold front may pose a risk
for damaging winds and a brief tornado or two late this afternoon
and evening. A severe thunderstorm watch could be needed later this
afternoon or early this evening if storms are able to organize.

DISCUSSION...1800Z surface obs showed a broad plume of 60s F
dewpoints stretching from the Carolina Piedmont northward into
eastern Virginia. To the west, a slow moving cold front associated
with low pressure across the Northeast was located along the spine
of the Appalachians. A large band of cloud debris and stratiform
precipitation are ongoing along and east of the front. Clear skies
along and east of the differential heating axis have allowed
temperatures to warm into the upper 70s to low 80s F across the
eastern Carolinas and Virginia. While mid-level lapse rates remain
poor (5-6 C/km), modest destabilization is occurring, and should
continue through the afternoon. MLCAPE of 500-1000 J/kg is expected
from central South Carolina northward into southern Virginia. This
buoyancy should be sufficient to support thunderstorm development
along the eastern edge of the differential heating axis this
afternoon. The most likely corridor for severe weather appears to be
across southern North Carolina and east-central South Carolina where
greater heating/destabilization is occurring. Deep-layer shear of
30-40 kts oriented parallel to the zone of initiation should favor a
quasi-linear mode with the primary risk being damaging wind gusts.
Given the linear storm mode and limited low-level shear, the tornado
risk is likely low. However, a brief tornado or two may occur with
any stronger QLCS/embedded supercell segments and localized areas of
backed surface flow. Trends will be monitored for a possible severe
thunderstorm watch to cover the risk of damaging wind gusts/a brief
tornado later this afternoon into early this evening.

..Lyons/Grams.. 03/31/2021

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

ATTN...WFO...AKQ...MHX...RAH...ILM...RNK...CAE...GSP...

LAT...LON   36777871 37107815 37147742 37077705 36897660 36717651
            36377634 35937646 35137702 34547766 33967873 33767921
            33378061 33278098 33338147 33648196 34218200 34348183
            34778124 35478020 36147942 36777871

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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.