MESO: Mesoscale Discussion 1706

ACUS11 KWNS 131804
SWOMCD
SPC MCD 131804
LAZ000-ARZ000-TXZ000-OKZ000-132030-

MESOSCALE DISCUSSION 1706
NWS STORM PREDICTION CENTER NORMAN OK
0104 PM CDT TUE AUG 13 2013

AREAS AFFECTED...PORTIONS OF N TX...SRN OK...SWRN AR...NWRN LA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 131804Z - 132030Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A FEW STORMS MAY BRIEFLY BECOME MARGINALLY SVR THIS
AFTERNOON.

DISCUSSION...ISOLATED TO WIDELY SCATTERED THUNDERSTORMS ARE
BEGINNING TO BLOSSOM FROM A BROADER AREA OF ACCAS S OF THE RED RIVER
AND E OF THE LOW ROLLING PLAINS IN N TX...PER RECENT VIS SATELLITE
IMAGERY AND LIGHTNING DATA. THIS AREA LIES TO THE S OF A
W/E-ORIENTED DIFFERENTIAL HEATING ZONE DRAPED ACROSS SRN OK. ASCENT
ACCOMPANYING STRENGTHENING BAROCLINIC CIRCULATIONS ATTENDANT TO THIS
ZONE...WEAK LOW-LEVEL CONVERGENCE ALONG A W/E-ORIENTED OUTFLOW
BOUNDARY EXTENDING ROUGHLY PARALLEL TO/JUST N OF THE AR/LA BORDER
AND WWD ACROSS FAR NRN TX PER SFC OBS...AND DIURNALLY DEEPENING PBL
CIRCULATIONS AMIDST A MOIST AIR MASS WITH RELATIVELY LOW
CINH...SHOULD ALL SERVE AS FOCI FOR AN UPTICK IN CONVECTIVE
COVERAGE/INTENSITY THROUGH THE AFTERNOON. A MODERATELY UNSTABLE AIR
MASS S OF THE DIFFERENTIAL HEATING ZONE WILL SERVE TO SUPPORT A FEW
VIGOROUS UPDRAFTS/DOWNDRAFTS...WITH THE MOST INTENSE CONVECTIVE
CORES CAPABLE OF BRIEFLY PRODUCING MARGINALLY SVR WIND -- AIDED BY
RELATIVELY HIGH PW -- AND PERHAPS MAINLY SMALL HAIL.

HOWEVER...MORE SUBSTANTIVE DEEP SHEAR SHOULD REMAIN RELEGATED TO THE
COOL SIDE OF THE DIFFERENTIAL HEATING ZONE -- IN CLOSER PROXIMITY TO
A DEEPER FRONTAL CIRCULATION. THIS IS WHERE STABLE THERMODYNAMIC
PROFILES OWING TO WIDESPREAD MULTI-LAYERED CLOUDS SHOULD LARGELY
MITIGATE THE SVR THREAT. RELATIVELY WEAK TROPOSPHERIC FLOW ACROSS
THE MCD AREA SHOULD LARGELY LIMIT THE ORGANIZATION/SUSTENANCE OF
INDIVIDUAL CONVECTIVE ELEMENTS...AND PRECLUDE A MORE SUBSTANTIAL SVR
THREAT FROM EVOLVING.

..COHEN/KERR.. 08/13/2013

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

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...SJT...LUB...

LAT...LON 34380015 34389652 33959320 33029247 32289312 32019574
32179865 32930051 33810089 34380015

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