Alert archive / North Carolina / Mesoscale Discussions in 2021
Mesoscale Discussion 128
The Storm Prediction Center issued this mesoscale discussion at Feb 22, 2021, 1:24 PM EST for 23 counties in North Carolina; 7 counties in Virginia. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Feb 22, 2021, 1:24 PM EST (18:24 UTC)
- Expired
- Feb 22, 2021, 3:30 PM EST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
All 30 counties
Beaufort County, NC, Bertie County, NC, Camden County, NC, Chowan County, NC, Craven County, NC, Edgecombe County, NC, Gates County, NC, Greene County, NC, Halifax County, NC, Hertford County, NC, Jones County, NC, Lenoir County, NC, Martin County, NC, Nash County, NC, Northampton County, NC, Pamlico County, NC, Pasquotank County, NC, Perquimans County, NC, Pitt County, NC, Tyrrell County, NC, Washington County, NC, Wayne County, NC, Wilson County, NC, City of Chesapeake, VA, City of Franklin, VA, City of Norfolk, VA, City of Portsmouth, VA, City of Suffolk, VA, Isle of Wight County, VA, Southampton County, VA
The radar
The Norfolk radar (KAKQ), 108 km from the middle of the area, began a volume at 18:25 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
Newport, NC (KMHX), launched 12:00Z, 6.4 hours before the alert went out and 141 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
- 1057 m above ground
- 0-6 km bulk shear
- 65 kt
- 0-1 km storm-relative helicity
- 334 m²/s²
- 0-3 km storm-relative helicity
- 375 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
341
ACUS11 KWNS 221824
SWOMCD
SPC MCD 221824
NCZ000-VAZ000-222030-
Mesoscale Discussion 0128
NWS Storm Prediction Center Norman OK
1224 PM CST Mon Feb 22 2021
Areas affected...Eastern North Carolina and Southeastern Virginia
Concerning...Severe potential...Watch unlikely
Valid 221824Z - 222030Z
Probability of Watch Issuance...20 percent
SUMMARY...Strong, damaging wind gusts will be possible as a line of
shallow convection intensifies this afternoon across eastern North
Carolina and southeastern Virginia. Minimal buoyancy should limit
the overall threat. No WW is anticipated this afternoon.
DISCUSSION...Recent radar imagery from KRAX/KAKQ have shown a more
defined line of precipitation along the advancing cold front.
Modifying the observed 12Z GSO sounding with RDU surface conditions
suggests very shallow 100-200 J/kg MUCAPE has developed. With
temperatures in the low 60s F ahead of the line and dewpoints now in
the upper 40s to low 50s F, convection along the front is expected
to deepen and intensify in the next 1-2 hours. Warm temperatures
aloft should will tend to keep convection shallow enough that
lightning may not be all that prevalent even as the convection
reaches peak intensity. However, regional VAD profiles show very
strong flow of greater than 50 kts in the lowest 3 km. Even modest
momentum transfer within the convective line could produce damaging
wind gusts. Parts of east-central and northeastern North Carolina
have seen more surface heating today and are likely the areas where
buoyancy will be maximized. A WW is not anticipated given the very
poor thermodynamic environment.
..Wendt/Thompson.. 02/22/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...MHX...RAH...
LAT...LON 35437818 35647830 35937817 36307782 36727750 36957714
37087679 37067634 36827604 36517603 36127596 35447634
34967682 34807733 35177801 35437818Nearby
Mesoscale Discussions in North Carolina, 2021Mesoscale Discussions in 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.