Alert archive / Virginia / Mesoscale Discussions in 2021
Mesoscale Discussion 1373
The Storm Prediction Center issued this mesoscale discussion at Jul 28, 2021, 12:36 PM EDT for 34 counties in North Carolina; 38 counties in Virginia. It was in force for 114 min.
The area
The outline as issued.
The facts
- Issued
- Jul 28, 2021, 12:36 PM EDT (16:36 UTC)
- Expired
- Jul 28, 2021, 2:30 PM EDT
- In force
- 114 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch likely
- Chance of a watch
- 80%
All 72 counties
Beaufort County, NC, Bertie County, NC, Bladen County, NC, Camden County, NC, Chowan County, NC, Craven County, NC, Currituck County, NC, Dare County, NC, Duplin County, NC, Edgecombe County, NC, Franklin County, NC, Gates County, NC, Greene County, NC, Halifax County, NC, Hertford County, NC, Hyde County, NC, Johnston County, NC, Jones County, NC, Lenoir County, NC, Martin County, NC, Nash County, NC, Northampton County, NC, Onslow County, NC, Pamlico County, NC, Pasquotank County, NC, Pender County, NC, Perquimans County, NC, Pitt County, NC, Sampson County, NC, Tyrrell County, NC, Warren County, NC, Washington County, NC, Wayne County, NC, Wilson County, NC, Accomack County, VA, Brunswick County, VA, Charles City County, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Franklin, VA, City of Hampton, VA, City of Hopewell, VA, City of Newport News, VA, City of Norfolk, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Dinwiddie County, VA, Essex County, VA, Gloucester County, VA, Greensville County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King William County, VA, Lancaster County, VA, Mathews County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Prince George County, VA, Richmond County, VA, Southampton County, VA, Surry County, VA, Sussex County, VA, York County, VA
The radar
The Norfolk radar (KAKQ), 113 km from the middle of the area, began a volume at 16:37 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
Newport, NC (KMHX), launched 12:00Z, 4.6 hours before the alert went out and 135 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
- 2446 J/kg
- Mixed-layer CIN
- -4 J/kg
- Mixed-layer LCL
- 613 m above ground
- 0-6 km bulk shear
- 21 kt
- 0-1 km storm-relative helicity
- 61 m²/s²
- 0-3 km storm-relative helicity
- 44 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.0
The text
As transmitted.
334
ACUS11 KWNS 281636
SWOMCD
SPC MCD 281636
VAZ000-NCZ000-MDZ000-281830-
Mesoscale Discussion 1373
NWS Storm Prediction Center Norman OK
1136 AM CDT Wed Jul 28 2021
Areas affected...Southeastern Virginia and eastern North Carolina
Concerning...Severe potential...Watch likely
Valid 281636Z - 281830Z
Probability of Watch Issuance...80 percent
SUMMARY...Damaging winds and isolated large hail are possible with
organized multicells and isolated supercells storms this afternoon.
A watch is likely in the next 1-2 hours.
DISCUSSION...With convective temperatures already being reached
across parts of eastern Virginia and eastern North Carolina, storm
coverage is expected to increase this afternoon within a weak, but
modestly deepening, surface trough. Signs of this are already
evident in southeastern Virginia where cumulus have deepened and a
storm has recently developed near the southern Chesapeake Bay.
Continued mid-level cooling and effective shear (30-40 kts)
supportive of organized storms, the threat for damaging winds and
isolated large hail will continue to increase through the afternoon.
A severe thunderstorm watch is likely this afternoon, though timing
on when storm coverage will be sufficient is somewhat uncertain.
Observational trends along with model guidance would suggest a watch
would be needed in the next 1-2 hours.
..Wendt/Hart.. 07/28/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...MHX...LWX...RAH...ILM...
LAT...LON 35357883 37517749 38117676 37997573 37297532 35857552
35257608 34457757 34217796 34367853 35357883SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 28, 2:19 PM EDT | Severe Thunderstorm Watch | SPC | Beaufort, Bertie, Camden, Carteret, Chowan, Craven and 29 more | 6 hr |
| Jul 28, 4:16 PM EDT | Mesoscale Discussion | SPC | Beaufort, Bertie, Camden, Chowan, Craven, Cumberland and 23 more | 119 min |
| Jul 28, 6:07 PM EDT | Mesoscale Discussion | SPC | Anson, Bladen, Brunswick, Columbus, Cumberland, Duplin and 8 more | 83 min |
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; radar from the NEXRAD Level II archive.