MESO: Mesoscale Discussion 2157

ACUS11 KWNS 102240
SWOMCD
SPC MCD 102239
CAZ000-110115-

MESOSCALE DISCUSSION 2157
NWS STORM PREDICTION CENTER NORMAN OK
0539 PM CDT SAT SEP 10 2011

AREAS AFFECTED...CA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 102239Z - 110115Z

THE CHANCE FOR ISOLATED LARGE HAIL AND STRONG WIND GUSTS...AS WELL
AS VERY HEAVY RAIN...WILL CONTINUE FROM TSTMS ERUPTING OVER THE
HIGHER TERRAIN TO THE NORTH AND EAST OF THE LA BASIN LATE THIS
AFTERNOON. ISOLATED NATURE OF THE SEVERE WEATHER THREAT PRECLUDES A
WATCH AT THIS TIME.

A PLUME OF HIGH PW AIR BEING WRAPPED NWWD INTO/AROUND THE NERN
QUADRANT OF LARGE SCALE UPPER LOW OFF THE CA COAST HAS COINCIDED
WITH STRONG DIFFERENTIAL HEATING AND MESOSCALE ASCENT ACROSS THE
MOUNTAINS OF SRN CA TO SUPPORT STRONG TO ISOLATED SEVERE TSTM
DEVELOPMENT THIS AFTERNOON. RECENT RADAR TRENDS SUGGEST THAT SOME OF
THE MORE INTENSE CELLS ARE ANCHORED TO TERRAIN AND MAY PERSIST GIVEN
CONTINUING LOW LEVEL CONVERGENCE AND UPSLOPE FLOW NORTH AND EAST OF
LA AND SAN BERNARDINO. MLCAPE AROUND 1000 J/KG FEEDING INTO THIS
AREA IS MORE THAN ADEQUATE TO SUPPORT A CONTINUATION OF SCATTERED
STRONG STORM UPDRAFTS. MAIN LIMITATION FOR A GREATER SEVERE WEATHER
THREAT APPEARS TO BE LACK OF DEEP-LAYER SHEAR. MID LEVEL FLOW WITHIN
THE ERN SEMI-CIRCLE OF UPPER LOW CIRCULATION IS EXPECTED TO REMAIN
QUITE WEAK. HOWEVER...COLDER MID LEVEL TEMPERATURES AOB -12C
ASSOCIATED WITH THIS SYSTEM SHOULD CONTRIBUTE TO A SLIGHTLY GREATER
CHANCE FOR HAIL WITH A FEW OF THE STORMS. WEAK PROPAGATION AND
TERRAIN INFLUENCES ALSO SUGGEST THAT LOCALLY VERY HEAVY RAIN CAN BE
EXPECTED WITH THIS CONVECTION INTO THE EVENING.

..CARBIN.. 09/10/2011

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

ATTN...WFO...VEF...SGX...HNX...LOX...

LAT...LON 34731631 34221677 34391869 34661954 34861969 35121968
35301943 35701917 35821890 35361861 35191850 35071811
35021782 34891731 34781681 34751667 34731631

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