Monday, February 16, 2009

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 161302
SWODY1
SPC AC 161259

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0659 AM CST MON FEB 16 2009

VALID 161300Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CNTRL AND SRN
CA...

...SYNOPSIS...
CLOSED LOW OFF THE NRN CA CST WILL REDEVELOP SE TOWARD SFO THIS
PERIOD AS DOWNSTREAM RIDGE PROGRESSES FROM THE SRN RCKYS/HI PLNS TO
THE OZARKS/WRN GULF CST. ONSHORE FLOW WILL STRENGTHEN AND DEEPEN
ALONG THE SRN CA CST TODAY AS VORT MAX NOW NEAR 34N/125W MOVES ENE
INTO S CNTRL CA BY EVE.

...CNTRL/SRN CA...
LEAD COLD FRONT ASSOCIATED WITH OFFSHORE LOW HAS ALREADY MOVED
INLAND ACROSS PART OF THE CNTRL VLY AND IS NEARING THE LAX AREA IN
SRN CA. THIS FEATURE WILL BE FOLLOWED BY SECONDARY FRONTAL ZONE
MORE CLOSELY ASSOCIATED WITH AFOREMENTIONED UPR VORT. LOW TO MID LVL
LAPSE RATES SHOULD SUBSTANTIALLY STEEPEN ACROSS CNTRL AND SRN CA
LATER TODAY IN RESPONSE TO MID LVL COOLING WITH UPR VORT AND
FAVORABLY-TIMED SFC HEATING. COUPLED WITH INCREASED ASCENT AHEAD OF
VORT AND FOCUSED UPLIFT NEAR SECONDARY FRONT...EXPECT CONSIDERABLE
COVERAGE OF SHOWERS/TSTMS BY AFTN FROM THE L.A. BASIN NWD INTO MUCH
OF CNTRL CA.

LIFT SHOULD BE MAXIMIZED IN LAX AREA THIS AFTN AS THE EXIT REGION OF
A 80+ KT MID LVL JET APPROACHES THE SRN CA CST...ENHANCING DEEP
SHEAR. COMBINATION OF INCREASING SHEAR AND DESTABILIZATION WITH LOW
FREEZING LVLS SHOULD SUPPORT STORMS WITH HAIL...ESPECIALLY NEAR THE
CST AND PERHAPS IN SRN/CNTRL PARTS OF THE CNTRL VLY. IN ADDITION...
TOPOGRAPHICALLY-INFLUENCED 40+ KT LLJ IN THE L.A. BASIN AND...TO A
LESSER EXTENT IN THE CNTRL VLY...LIKELY WILL EXIST TO ENHANCE LOW
LVL SHEAR WITH ANY SUSTAINED STORMS THAT DO FORM. THUS...POTENTIAL
WILL EXIST FOR ISOLD TORNADOES AND/OR WATERSPOUTS. THE STORMS
SHOULD WEAKEN AS UPR VORT CONTINUES INLAND AND BOUNDARY LAYER
DIURNALLY COOLS LATER TODAY/TONIGHT.

..CORFIDI.. 02/16/2009

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