MESO: Mesoscale Discussion 1785

ACUS11 KWNS 272151
SWOMCD
SPC MCD 272150
AZZ000-280015-

MESOSCALE DISCUSSION 1785
NWS STORM PREDICTION CENTER NORMAN OK
0450 PM CDT TUE AUG 27 2013

AREAS AFFECTED...PORTIONS OF CNTRL/S-CNTRL AZ

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 272150Z - 280015Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...AN ISOLATED...MARGINALLY SVR WIND GUST CANNOT BE RULED OUT
INTO THE EVENING HOURS.

DISCUSSION...TERRAIN-DRIVEN CIRCULATIONS HAVE AIDED IN THE
DEVELOPMENT OF ISOLATED TO WIDELY SCATTERED THUNDERSTORMS AMIDST A
MARGINALLY UNSTABLE AIR MASS FROM THE MOGOLLON RIM IN CNTRL/ERN AZ
TO THE SERN AZ MOUNTAINS. A NONZERO ELY COMPONENT OF THE FLOW BELOW
5 KM AGL SAMPLED BY AREA VWP SUGGESTS THAT CONVECTION MAY HAVE A
TENDENCY OF SPREADING ACROSS THE LOWER ELEVATIONS/DESERT FLOORS OF
S-CNTRL AZ INTO THE EVENING HOURS. GPS DATA INDICATE THAT RELATIVELY
RICHER TROPOSPHERIC MOISTURE -- PW OVER 1.5 INCHES -- EXISTS ACROSS
WRN PARTS OF THE MCD AREA...WHERE MLCAPE EXCEEDS 1000 J/KG. THESE
FACTORS MAY ALLOW FOR SOME UPTICK IN CONVECTIVE INTENSITY IF STORMS
DEVELOP INTO THE MOISTER AIR LATER THIS AFTERNOON INTO THE EVENING.
LARGE SFC TEMPERATURE-DEWPOINT SPREADS BENEATH DEEP SFC-BASED MIXED
LAYERS WITH HIGH DCAPE MAY CONTRIBUTE TO STRONG WIND GUSTS...AND AN
ISOLATED MARGINALLY SVR WIND GUST CANNOT BE RULED OUT.
HOWEVER...WITH LOW/MID-LEVEL WIND SPEEDS GENERALLY LESS THAN 20 KT
PER THE VWP/S...CONVECTION SHOULD STRUGGLE TO ORGANIZE...AND LIKELY
PREVENT A GREATER SVR-WIND POTENTIAL FROM EVOLVING. OF
NOTE...CONVECTIVE COVERAGE AND THE SVR THREAT ARE EXPECTED TO BE
LESS TODAY THAN YESTERDAY...WITH PW HAVING DECREASED BY AROUND 0.5
INCH DURING THE PAST 24 HOURS.

..COHEN/HART.. 08/27/2013

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

ATTN...WFO...TWC...FGZ...PSR...

LAT...LON 32091346 33141362 34171342 34431235 34181137 33291081
31841061 31291083 31651233 32091346

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