MESO: Mesoscale Discussion 1944

ACUS11 KWNS 101947
SWOMCD
SPC MCD 101947
AZZ000-NVZ000-CAZ000-102145-

MESOSCALE DISCUSSION 1944
NWS STORM PREDICTION CENTER NORMAN OK
0247 PM CDT MON SEP 10 2012

AREAS AFFECTED...SRN INTERIOR CA...SRN NV...WRN/SRN AZ

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 101947Z - 102145Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...A FEW STORMS MAY PRODUCE SVR WIND GUSTS ON AN ISOLATED
BASIS INTO EARLY EVENING...AND WW ISSUANCE IS NOT NEEDED.

DISCUSSION...VISIBLE SATELLITE IMAGES SUGGEST CONVECTION INCREASING
OVER THE COASTAL RANGES FROM ERN LOS ANGELES COUNTY SWD INTO SAN
DIEGO COUNTY...AIDED BY UPSLOPE FLOW WITHIN THE NRN SEMICIRCLE OF A
MID-LEVEL LOW JUST WEST OF THE NRN COAST OF BAJA CA. SCATTERED
THUNDERSTORMS WILL LIKELY EVOLVE FROM THIS ACTIVITY THROUGH THE
AFTERNOON POTENTIALLY IMPACTING ADJACENT SECTIONS OF THE COASTAL
PLAIN...WHILE TERRAIN-DRIVEN CIRCULATIONS AND DIFFERENTIAL HEATING
ZONES SUPPORT ADDITIONAL STORMS FARTHER EAST TOWARD THE LOWER CO
RIVER VALLEY INTO S-CNTRL AZ. PW VALUES OF GENERALLY 1.5-2.1 INCHES
WILL BOLSTER WATER-LOADING PROCESSES TO SUPPORT THE POTENTIAL FOR
STRONG/LOCALLY SVR WIND GUSTS...AIDED IN SERN CA AND SWRN AZ BY
20-25 KT OF LOW-TO-MID-LEVEL SSELY FLOW -- REF. YUMA VWP DATA. THE
THREAT WILL BE GREATEST WHERE SFC HEATING HAS BEEN MAXIMIZED IN
PERSISTENTLY CLOUD-FREE AREAS. HOWEVER...WEAK HIGH-LEVEL FLOW
YIELDING WEAK EFFECTIVE-LAYER SHEAR...AND WEAK MID-LEVEL LAPSE
RATES...SHOULD KEEP ANY INSTANCES OF SVR STORMS ISOLATED.

..COHEN/THOMPSON.. 09/10/2012

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

ATTN...WFO...TWC...FGZ...PSR...VEF...SGX...LOX...

LAT...LON 32541623 32501649 32591690 32971701 33321713 33761745
34041775 34371793 34671753 35161679 36251572 36241409
34901354 33961208 33271130 32071098 31491141 31811271
32051344 32561428 33261464 33361505 33321544 33091586
32541623

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