ZCZC SPCSWOMCD ALL
ACUS11 KWNS 080729 
SPC MCD 080729 
ARZ000-OKZ000-TXZ000-081030-

MESOSCALE DISCUSSION 1321
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT WED JUL 08 2015

AREAS AFFECTED...EAST-CENTRAL TO SOUTH-CENTRAL OK...WESTERN AR AND
FAR NORTH-CENTRAL TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 080729Z - 081030Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...LOCALLY STRONG WIND GUSTS AND/OR A BRIEF...WEAK TORNADO
CANNOT BE RULED OUT WITH STORMS THAT CONTINUE TO DEVELOP OVERNIGHT
INTO EARLY THIS MORNING FROM FAR NORTH-CENTRAL TX INTO SOUTH-CENTRAL
AND PARTS OF EASTERN OK AND NORTHWEST AR.

DISCUSSION...EARLY OVERNIGHT SURFACE ANALYSES SHOWED A FRONT
EXTENDING WWD THROUGH SRN MO INTO NERN OK...AND THEN SWWD TO AN AREA
OF LOW PRESSURE IN SOUTH-CENTRAL OK /APPROXIMATELY 25 SE CHK/ AND
THEN THROUGH NORTH-CENTRAL INTO CENTRAL TX.  THE INCREASE IN
LIGHTNING SINCE 04-05Z ALONG THIS BOUNDARY LIKELY INDICATES THE
INCREASE IN DEEP LAYER ASCENT ATTENDANT TO 1/ EXPECTED STRENGTHENING
OF A SSWLY LLJ /40-45 KT/ ALONG AND EAST OF THIS FRONT FROM TX INTO
ERN OK/WRN AR OVERNIGHT TO EARLY THIS MORNING...AND 2/ DPVA
ATTENDANT TO A WEAK SHORTWAVE TROUGH TRACKING ENEWD INTO SRN OK AT
THIS TIME.  ALTHOUGH LAPSE RATES ARE QUITE WEAK...THE PRESENCE OF
RICH MOISTURE /PW VALUES OF 2-2.25 INCHES/ IS SUPPORTING WEAK
INSTABILITY.

00Z ECMWF SUGGESTS THE SURFACE LOW WILL DEEPEN AS IT REACHES
NORTHEAST OK BY 12Z...FURTHER ENHANCING LOW-LEVEL CONVERGENCE. 
EASTERLY SURFACE WINDS OVER ERN OK TO WRN AR ARE ENHANCING LOW-LEVEL
SHEAR NEAR THE SURFACE FRONT...WITH RADAR IMAGERY INDICATING MOST
CELLS ALONG THE FRONT HAVE SOME ROTATION AND A FEW HAVE HAD
PERSISTENT ROTATIONAL COUPLETS.  OBJECTIVE ANALYSES INDICATED
EFFECTIVE SRH OF 100-200 M2/S2 ALONG AND EAST OF THE FRONT IN SRN TO
ERN OK WITH SIMILAR VALUES FORECAST TO SPREAD INTO WRN AR THROUGH
EARLY MORNING WITH THE APPROACH OF THE SURFACE LOW AND MIDLEVEL
TROUGH.  ALTHOUGH INSTABILITY WILL REMAIN QUITE WEAK...A BRIEF
TORNADO AND/OR LOCALLY STRONG WIND GUST CANNOT BE RULED OUT THROUGH
EARLY MORNING.  GIVEN THE LIKELIHOOD FOR THE LLJ TO PERSIST INTO
THIS MORNING AND FURTHER DEEPENING OF THE TRANSIENT SURFACE
LOW...THE POTENTIAL EXISTS FOR ADDITIONAL TSTMS...INCLUDING LINE
SEGMENTS. ALTHOUGH THE POTENTIAL FOR A WATCH IS RELATIVELY
LOW...THIS REGION WILL BE MONITORED FOR ANY INCREASE IN TSTM
INTENSITIES AND COVERAGE THAT COULD WARRANT THE NEED FOR A WATCH.

..PETERS/CORFIDI.. 07/08/2015

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

ATTN...WFO...TSA...FWD...OUN...

LAT...LON   34909732 35569646 36319542 36449496 36309429 36089394
            35769391 35299438 34699522 34069604 33699662 33499731
            33579793 34909732 

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