MESO: Mesoscale Discussion 1700

ACUS11 KWNS 121926
SWOMCD
SPC MCD 121926
SDZ000-NEZ000-122200-

MESOSCALE DISCUSSION 1700
NWS STORM PREDICTION CENTER NORMAN OK
0226 PM CDT MON AUG 12 2013

AREAS AFFECTED...PORTIONS OF SD AND NRN NEB

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 121926Z - 122200Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...AN ISOLATED SVR THREAT MAY DEVELOP AND PERSIST INTO THE
EVENING HOURS. WHILE CONVECTIVE TRENDS WILL BE MONITORED...WW
ISSUANCE IS CURRENTLY UNLIKELY.

DISCUSSION...VISIBLE SATELLITE DATA INDICATE A CUMULUS FIELD
BECOMING INCREASINGLY AGITATED ALONG A DIFFUSE FRONT THAT EXTENDS
NW-SE ACROSS SD INTO NERN NEB...PARTLY OWING TO INSOLATION/DIABATIC
HEATING SERVING TO REDUCE CINH. SFC DEWPOINTS IN THE LOWER/MIDDLE
60S AMIDST MODEST LOW/MID-LEVEL LAPSE RATES ARE SUPPORTING MLCAPE
VALUES AROUND 1000-2500 J/KG PER MODIFIED 12Z RAOBS. CONTINUED
DIURNAL HEATING ALONG WITH WEAK FRONTAL CONVERGENCE MAY BE
SUFFICIENT FOR ISOLATED TO PERHAPS WIDELY SCATTERED THUNDERSTORM
DEVELOPMENT THROUGH THE AFTERNOON. CUMULUS DEVELOPMENT ALSO
CONTINUES OVER THE BLACK HILLS...AND THIS ELEVATED HEAT SOURCE MAY
BE A FOCUS FOR ADDITIONAL CONVECTIVE INITIATION.

A CHANNEL OF ENHANCED WNWLY/NWLY MID-LEVEL FLOW SUPPORTING AROUND
30-40 KT OF EFFECTIVE DEEP SHEAR MAY YIELD A FEW SUSTAINED/ORGANIZED
CONVECTIVE STRUCTURES WITH ISOLATED INSTANCES OF SVR WIND/HAIL
POSSIBLE. THIS WOULD ESPECIALLY BE THE CASE IF ONE OR MORE
SEWD/SSEWD-MOVING STORM CLUSTERS WERE TO EVOLVE LATER THIS AFTERNOON
INTO THE EVENING FROM LOCALIZED UPSCALE CONVECTIVE GROWTH.

HOWEVER...WATER VAPOR DATA INDICATE THE LACK OF ANY SALIENT
MID-LEVEL DISTURBANCES...AND LOW-LEVEL FLOW/CONVERGENCE WILL LIKELY
REMAIN RELATIVELY WEAK. THESE FACTORS SHOULD PREVENT A MORE
ORGANIZED/WIDESPREAD SVR THREAT FROM EVOLVING...THOUGH TRENDS WILL
CONTINUE TO BE MONITORED.

..COHEN/KERR.. 08/12/2013

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

ATTN...WFO...FSD...OAX...ABR...LBF...UNR...CYS...

LAT...LON 42519796 42209991 42550236 43500371 44780386 45580206
44999934 43559771 42519796

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.