Mesoscale Discussion 780

Issued

May 19, 2017, 2:24 PM EDT (18:24 UTC)

Expired

May 19, 2017, 4:30 PM EDT

In force

2 hr

Issued by

the Storm Prediction Center

Chance of a watch

20%

The Roanoke radar (KFCX), 83 km from the middle of the area, began a volume at 18:24 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.

588 
ACUS11 KWNS 191825
SWOMCD
SPC MCD 191824 
VAZ000-NCZ000-192030-

Mesoscale Discussion 0780
NWS Storm Prediction Center Norman OK
0124 PM CDT Fri May 19 2017

Areas affected...Portions of southern VA and western/central NC

Concerning...Severe potential...Watch unlikely 

Valid 191824Z - 192030Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated strong to locally damaging wind risk should
persist through the afternoon, along with some marginally severe
hail threat. Thunderstorms should remain mostly disorganized, and
watch issuance appears unlikely at this time.

DISCUSSION...18Z surface analysis depicts a trough extending from
southern New England into the Mid-Atlantic. Isolated to scattered
convection has developed along this surface trough and the higher
terrain of western NC over the past several hours. Temperatures have
generally warmed into the 80s as of 18Z with ample diurnal heating,
and a moist low-level airmass characterized by surface dewpoints in
the upper 60s to lower 70s is present across much of southern VA
into western/central NC. Although poor to modest mid-level lapse
rates exist across this region per 12Z soundings from RNK and GSO
(generally 5.5-6.5 C/km in the 700-500 mb layer), strong heating has
allowed MLCAPE to increase into the 1000-2000 J/kg range per 18Z RAP
Mesoanalysis.

However, both low and mid-level winds are expected to remain
weak/modest through this evening, generally 25-30 kt or less. The
lack of stronger winds through most of the troposphere should tend
to limit updraft organization, and the overall severe risk should
remain marginal with watch issuance unlikely at this time. Still,
isolated/sporadic tree damage and marginally severe hail may occur
with the strongest cells. Several recent runs of the operational
HRRR have suggested some potential for a loosely organized cluster
of storms to evolve eastward along the NC/VA border from the higher
terrain of western NC. If this scenario were to become apparent in
observational data, then watch probabilities may increase.

..Gleason/Kerr.. 05/19/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...AKQ...RAH...RNK...GSP...

LAT...LON   35678206 36628150 37018136 37637783 37627711 37287684
            36307702 35917928 35388104 35268190 35278243 35678206

Mesoscale Discussions in Virginia, 2017Mesoscale Discussions in North Carolina, 2017Every mesoscale discussion in 2017

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.