Alert archive / Virginia / Mesoscale Discussions in 2017
Mesoscale Discussion 810
The Storm Prediction Center issued this mesoscale discussion at May 22, 2017, 2:16 PM EDT for 6 counties in North Carolina; 8 counties in Virginia. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- May 22, 2017, 2:16 PM EDT (18:16 UTC)
- Expired
- May 22, 2017, 3:45 PM EDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 5%
Counties Camden County, NC, Chowan County, NC, Currituck County, NC, Gates County, NC, Pasquotank County, NC, Perquimans County, NC, City of Chesapeake, VA, City of Franklin, VA, City of Hampton, 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), 85 km from the middle of the area, began a volume at 18:19 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
Wallops Is Stn, VA (KWAL), launched 12:00Z, 6.3 hours before the alert went out and 185 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
- 23 J/kg
- Mixed-layer CIN
- -72 J/kg
- Mixed-layer LCL
- 679 m above ground
- 0-6 km bulk shear
- 22 kt
- 0-1 km storm-relative helicity
- 89 m²/s²
- 0-3 km storm-relative helicity
- 96 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
237
ACUS11 KWNS 221816
SWOMCD
SPC MCD 221816
NCZ000-VAZ000-221945-
Mesoscale Discussion 0810
NWS Storm Prediction Center Norman OK
0116 PM CDT Mon May 22 2017
Areas affected...Portions of southeastern VA and northeastern NC
Concerning...Severe potential...Watch unlikely
Valid 221816Z - 221945Z
Probability of Watch Issuance...5 percent
SUMMARY...Localized strong/gusty winds may occur with thunderstorms
over the next hour or two. A brief tornado also cannot be ruled out.
Due to the marginal overall threat and small spatial/temporal nature
of the severe risk, watch issuance is not expected.
DISCUSSION...A MCV that developed from earlier convection is located
over southeastern VA as of 18Z. A small band of thunderstorms
associated with the MCV circulation has recently developed across
part of southeastern VA and northeastern NC. Visible satellite
imagery shows clearing downstream of this activity, and temperatures
have generally warmed into the lower 80s, with dewpoints in the
upper 60s to lower 70s. This moist low-level airmass and diurnal
heating have contributed to the development of weak instability
across this region, with MLCAPE up to 500 J/kg, even though
mid-level lapse rates remain poor. Given the linear nature of this
small band of convection, locally strong/gusty winds may occur over
the next hour or two as it moves eastward to the coast and then
offshore. In addition, a brief tornado cannot be completely ruled
out with the MCV circulation itself given the veering wind profile
noted in the AKQ VWP, as well as recent velocity data from the AKQ
radar. Due to the overall marginal thermodynamic environment and
small spatial/temporal nature of the severe risk, watch issuance is
not expected.
..Gleason/Weiss.. 05/22/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...AKQ...MHX...
LAT...LON 35947670 36247686 36947700 37117636 37017587 36587576
36227564 35977610 35947670Nearby
Mesoscale Discussions in Virginia, 2017Mesoscale Discussions in North Carolina, 2017Every mesoscale discussion in 2017
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.