Mesoscale Discussion 1585

Issued

Jul 25, 2012, 3:11 PM EDT (19:11 UTC)

Expired

Jul 25, 2012, 5:45 PM EDT

In force

3 hr

Issued by

the Storm Prediction Center

Chance of a watch

20%

The Knoxville radar (KMRX), 109 km from the middle of the area, began a volume at 19:10 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

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934 
ACUS11 KWNS 251911
SWOMCD
SPC MCD 251911 
NCZ000-VAZ000-TNZ000-SCZ000-GAZ000-252145-

MESOSCALE DISCUSSION 1585
NWS STORM PREDICTION CENTER NORMAN OK
0211 PM CDT WED JUL 25 2012

AREAS AFFECTED...SWRN VA...ERN TN...WRN NC...FAR NERN GA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 251911Z - 252145Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...AN ISOLATED SVR THREAT WILL EXIST THROUGH THE AFTERNOON.
WHILE CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED...THE ISSUANCE
OF A WW IS CURRENTLY UNLIKELY.

DISCUSSION...AMIDST POCKETS OF DIURNAL HEADING WITHIN THE MOIST SIDE
OF A PW GRADIENT ZONE LYING FROM THE OH VALLEY TO THE
CAROLINAS...DESTABILIZATION IS UNDERWAY ACROSS PARTS OF THE
CNTRL/SRN APPALACHIANS. MLCAPE VALUES OF 1500-2500 J/KG ARE COMMON
ACROSS MUCH OF THE AREA -- HIGHEST ON THE WARM SIDE OF A
CONVECTIVELY REINFORCED BOUNDARY -- PER MODIFIED 12Z OBSERVED
SOUNDINGS.

OROGRAPHIC ASCENT WILL CONTINUE TO SUPPORT AN UPTICK IN CUMULUS
DEVELOPMENT AND ISOLATED TO WIDELY SCATTERED THUNDERSTORMS THROUGH
THE AFTERNOON. THE AFOREMENTIONED BUOYANCY MAY YIELD STRONG
UPDRAFTS/DOWNDRAFTS...WITH THE STRONGEST STORMS CAPABLE OF PRODUCING
MARGINALLY SVR WIND GUSTS AND PERHAPS MARGINALLY SVR HAIL.

WITH THE PRIMARY ZONE OF STRONGER NWLYS REMAINING N OF THE
AREA...STORM ORGANIZATION IS EXPECTED TO BE GENERALLY LACKING.
HOWEVER...A LOCALIZED ZONE OF ENHANCED -- I.E. AROUND 30-35 KT --
NLY FLOW EXISTS WITHIN THE 3.5-4.5-KM-AGL LAYER PER AREA VWP
DATA...PERHAPS IN ASSOCIATION WITH A REMNANT MCV/PERTURBATION. IF
THIS FLOW IS ABLE TO BE MAINTAINED...A FEW MULTICELL CLUSTERS MAY
EVOLVE WITH RELATIVELY HIGHER CHANCES FOR PRODUCING DMGG WIND GUSTS.
REGARDLESS...UNCERTAINTY IN THE LONGEVITY OF THE MID-LEVEL FLOW
ENHANCEMENT...COMBINED WITH THE MAIN BELT OF STRONGER FLOW BEING
DISPLACED TO THE N OF THE AREA...LIMITS CONFIDENCE IN A THREAT FOR
ORGANIZED SVR STORMS. FURTHERMORE...VISIBLE SATELLITE IMAGES REVEAL
STABLE WAVE CLOUD FORMATIONS OVER THE MOUNTAINS OF FAR NERN TN AND
ADJACENT PARTS OF VA/NC INDICATING SOME ONGOING CONVECTIVE
INHIBITION. WHILE THIS INHIBITION MAY ERODE DURING THE NEXT COUPLE
OF HOURS OWING TO CONTINUED DIURNAL HEATING...IT COULD ALSO SERVE TO
LIMIT STORM/SVR COVERAGE.

..COHEN/HART.. 07/25/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...RAH...RNK...RLX...GSP...MRX...FFC...

LAT...LON   36848288 37088218 37208098 37068023 36458001 35558023
            35368070 35208144 35248228 34988313 34648356 34698417
            35218457 35978441 36848288

Mesoscale Discussions in North Carolina, 2012Mesoscale Discussions in Tennessee, 2012Mesoscale Discussions in Virginia, 2012Every mesoscale discussion in 2012

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.