Alert archive / Virginia / Mesoscale Discussions in 2019
Mesoscale Discussion 621
The Storm Prediction Center issued this mesoscale discussion at May 12, 2019, 3:37 PM EDT for 4 counties in North Carolina; 47 counties in Virginia. It was in force for 113 min.
The area
The outline as issued.
The facts
- Issued
- May 12, 2019, 3:37 PM EDT (19:37 UTC)
- Expired
- May 12, 2019, 5:30 PM EDT
- In force
- 113 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 5%
All 51 counties
Alleghany County, NC, Rockingham County, NC, Stokes County, NC, Surry 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, Charlotte County, VA, City of Buena Vista, VA, City of Danville, VA, City of Emporia, VA, City of Galax, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Petersburg, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Cumberland County, VA, Dinwiddie County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Grayson County, VA, Greensville County, VA, Halifax County, VA, Henry County, VA, Isle of Wight County, VA, Lunenburg County, VA, Mecklenburg County, VA, Montgomery County, VA, Nelson County, VA, Nottoway County, VA, Patrick County, VA, Pittsylvania County, VA, Prince Edward County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge County, VA, Smyth County, VA, Sussex County, VA, Wythe County, VA
The radar
The Roanoke radar (KFCX), 21 km from the middle of the area, began a volume at 19:38 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
Roanoke, VA (KRNK), launched 12:00Z, 7.6 hours before the alert went out and 52 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
- 107 J/kg
- Mixed-layer CIN
- -3 J/kg
- Mixed-layer LCL
- 541 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 228 m²/s²
- 0-3 km storm-relative helicity
- 234 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.4
The text
As transmitted.
085
ACUS11 KWNS 121937
SWOMCD
SPC MCD 121937
VAZ000-NCZ000-WVZ000-TNZ000-122130-
Mesoscale Discussion 0621
NWS Storm Prediction Center Norman OK
0237 PM CDT Sun May 12 2019
Areas affected...southern Virginia and northern North Carolina
Concerning...Severe potential...Watch unlikely
Valid 121937Z - 122130Z
Probability of Watch Issuance...5 percent
SUMMARY...A severe storm or two may evolve this afternoon across
southwestern Virginia and vicinity, along with attendant risk for
damaging wind gusts and marginal hail. Threat should remain too
isolated to warrant WW consideration.
DISCUSSION...Latest radar loop continues to show a very gradual
uptick in convective intensity across the southwestern Virginia
vicinity, near and just ahead of the slowly advancing surface cold
front. As temperatures have warmed into the mid 70s, surface-based
CAPE has reached 500 J/kg -- which has supported the deepening
convection.
As isolated storms develop over the next 1-2 hours, stronger
updrafts will be aided by gradually increasing flow with height that
is yielding 0-6km bulk shear near 50 kt -- though veered low-level
flow is yielding rather weak shear in the 0-1 km layer. With these
stronger cells, gusty/locally damaging winds and marginal hail will
likely be a concern through peak heating, until storms begin to
weaken diurnally.
..Goss/Grams.. 05/12/2019
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...LWX...RAH...RNK...MRX...
LAT...LON 36908208 37568022 38127946 36877662 36457851 36288129
36908208SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 12, 11:50 AM EDT | Mesoscale Discussion | SPC | Columbus | 85 min |
Nearby
Mesoscale Discussions in Virginia, 2019Mesoscale Discussions in North Carolina, 2019Every mesoscale discussion in 2019
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.