Alert archive / North Carolina / Mesoscale Discussions in 2021
Mesoscale Discussion 1883
The Storm Prediction Center issued this mesoscale discussion at Oct 22, 2021, 1:26 PM EDT for 18 counties in North Carolina; 7 counties in Virginia. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 22, 2021, 1:26 PM EDT (17:26 UTC)
- Expired
- Oct 22, 2021, 4:00 PM EDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
All 25 counties
Beaufort County, NC, Bertie County, NC, Camden County, NC, Chowan County, NC, Currituck County, NC, Dare County, NC, Edgecombe County, NC, Gates County, NC, Greene County, NC, Hertford County, NC, Hyde County, NC, Martin County, NC, Northampton County, NC, Pasquotank County, NC, Perquimans County, NC, Pitt County, NC, Tyrrell County, NC, Washington County, NC, City of Chesapeake, VA, City of Franklin, VA, City of Norfolk, VA, City of Portsmouth, VA, City of Suffolk, VA, City of Virginia Beach, VA, Isle of Wight County, VA
The radar
The Norfolk radar (KAKQ), 107 km from the middle of the area, began a volume at 17:29 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, 5.4 hours before the alert went out and 151 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
- 313 J/kg
- Mixed-layer CIN
- -51 J/kg
- Mixed-layer LCL
- 1077 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 18 m²/s²
- 0-3 km storm-relative helicity
- 48 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.1
The text
As transmitted.
852
ACUS11 KWNS 221727
SWOMCD
SPC MCD 221726
NCZ000-VAZ000-222000-
Mesoscale Discussion 1883
NWS Storm Prediction Center Norman OK
1226 PM CDT Fri Oct 22 2021
Areas affected...eastern North Carolina...southeast Virginia
Concerning...Severe potential...Watch possible
Valid 221726Z - 222000Z
Probability of Watch Issuance...40 percent
SUMMARY...Storms are expected to form around 19Z, and a few may
become severe. Isolated damaging gusts, marginal hail, and perhaps a
brief/weak tornado will be possible before storms move offshore
around 00Z.
DISCUSSION...Visible satellite and surface observations show a cold
front moving south across northern and central NC, with slower
speeds into southeast VA/northeast NC where a surface low is
forecast to develop. Lower to mid 60s F dewpoints exist ahead of the
front, with GPS water vapor sensors indicating up to 1.40" PWAT in
place.
With the help of heating, MUCAPE will increase to over 1500-2000
J/kg, beneath 40 kt midlevel southwesterlies. Low-level winds may
remain relatively backed near the weak low, resulting in sufficient
hodograph length and SRH to support a supercell or two. Cellular
storm mode would support marginal hail in this case, and a
brief/weak tornado cannot be ruled out as well.
While a watch is currently not anticipated, environmental trends
will continue to be monitored.
..Jewell/Thompson.. 10/22/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...MHX...RAH...
LAT...LON 35667542 35277620 35177724 35607785 36067781 36367748
36877693 37007644 36957594 36447578 36187568 35667542Nearby
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.