Mesoscale Discussion 920

Issued

Jun 9, 2014, 2:43 PM EDT (18:43 UTC)

Expired

Jun 9, 2014, 5:15 PM EDT

In force

3 hr

Issued by

the Storm Prediction Center

Chance of a watch

40%

The Columbia radar (KCAE), 19 km from the middle of the area, began a volume at 18:45 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.

• Severe Thunderstorm Watch 269Jun 9, 4:35 PM EDT

984 
ACUS11 KWNS 091844
SWOMCD
SPC MCD 091843 
NCZ000-SCZ000-GAZ000-092115-

MESOSCALE DISCUSSION 0920
NWS STORM PREDICTION CENTER NORMAN OK
0143 PM CDT MON JUN 09 2014

AREAS AFFECTED...MUCH OF SC...SRN NC...FAR ERN GA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 091843Z - 092115Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE REGION IS BEING MONITORED FOR AN INCREASING RISK OF
SEVERE THUNDERSTORMS THIS AFTERNOON. IT IS POSSIBLE THAT THIS COULD
REQUIRE THE ISSUANCE OF A SEVERE THUNDERSTORM WATCH.

DISCUSSION...DIURNAL HEATING AMIDST RELATIVELY RICH LOW-LEVEL
MOISTURE -- E.G. SFC DEWPOINTS IN THE MIDDLE 60S TO THE LOWER 70S --
IS SUPPORTING STRONG DESTABILIZATION ACROSS THE REGION.
MODIFICATIONS TO THE 12Z CHS RAOB FOR CURRENT SFC CONDITIONS
INDICATE MLCAPE AROUND 1500-2500 J/KG WITH LITTLE INHIBITION
REMAINING. THE STRONGEST INSTABILITY SUCCEEDS A BOUNDARY THAT IS
ADVANCING EWD ACROSS FAR ERN GA AND WRN SC. RICHER DEEP MOISTURE
BEHIND THIS BOUNDARY -- E.G. PW AROUND 1.5 INCHES PER GPS DATA --
AND ASSOCIATED STRONG BUOYANCY WILL CONTINUE TO OVERSPREAD THE
REGION. AS DIURNAL HEATING BOLSTERS OROGRAPHIC AND PBL
CIRCULATIONS...AND WEAK ASCENT AT THE LEADING EDGE OF THE DEEP
MOISTURE SURGE CONTINUES...CONVECTION WILL CONTINUE TO DEVELOP
ACROSS THE REGION. INITIAL DEVELOPMENT HAS ALREADY BEEN NOTED BY
RECENT RADAR REFLECTIVITY RETURNS INVOF THE NC/TN BORDER...WHILE
BOUNDARY-LAYER CU IS BECOMING INCREASINGLY AGITATED AT THE LEADING
EDGE OF THE MOISTURE SURGE.

THE AUGMENTATION TO THE FLOW ALOFT SURROUNDING AN MCV -- CURRENTLY
OVER NERN TN PER VIS IMAGERY -- IS LIKELY SUPPORTING THE 20-35-KT OF
WLYS/WNWLYS SAMPLED BY THE CAE AND GSP VWPS IN THE 2-3-KM LAYER. IN
ADDITION TO ENCOURAGING MODEST DEEP SHEAR...THIS ENHANCED FLOW ALOFT
WILL ALSO ACCELERATE DOWNWARD CONVECTIVE MOMENTUM TRANSPORT AS
MULTICELL CLUSTERS EVOLVE WITHIN THE STRONG BUOYANCY ACROSS THE
PIEDMONT AND COASTAL PLAIN -- ESPECIALLY IN SC -- DURING THE LATE
AFTERNOON INTO THE EVENING. DMGG WIND GUSTS -- AIDED BY DCAPE IN
EXCESS OF 1000 J/KG -- AND MARGINALLY SVR HAIL WILL BE THE PRIMARY
CONCERNS WITH THIS ACTIVITY. THE LACK OF STRONGER DEEP FORCING FOR
ASCENT MAY LIMIT THE OVERALL SVR RISK. HOWEVER...THERE IS SOME
POSSIBILITY THAT SUSTAINED CONVECTIVE CLUSTERS COULD FORWARD
PROPAGATE OVER THE LOWER ELEVATIONS WITH A SVR RISK TO WARRANT WW
ISSUANCE.

..COHEN/MEAD.. 06/09/2014

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

ATTN...WFO...RAH...ILM...CHS...CAE...GSP...FFC...

LAT...LON   33168220 34378279 35258236 35488150 35398059 34897904
            33997837 32787945 31988098 33168220

Mesoscale Discussions in South Carolina, 2014Mesoscale Discussions in North Carolina, 2014Mesoscale Discussions in Georgia, 2014Every mesoscale discussion in 2014

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.