DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 271224
SWODY1
SPC AC 271221

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0621 AM CST SUN JAN 27 2008

VALID 271300Z - 281200Z

..THERE IS A SLGT RISK OF SVR TSTMS COASTAL AREAS OF CENTRAL AND
SOUTHERN CALIFORNIA...

..COASTAL CENTRAL AND SRN CA...
COLD LOW OFF SCENTRAL CA COAST IN PROCESS OF BEING PICKED UP BY
VIGOROUS DIGGING TROUGH INTO PAC NW. STRONG SSWLY FLOW AHEAD OF
UPPER LOW HAS SPREAD A MOIST SUBTROPICAL AIRMASS RAPIDLY NEWD ACROSS
SWRN U.S.

AHEAD OF THE MAIN COLD UPPER LOW CIRCULATION WHICH AT 12Z IS LOCATED
NEAR 31N 126W OR ABOUT 300 MILES OFF SCENTRAL CA COAST...A VORT MAX
HAS ROTATED NWD TO W OF SFO. SFC LOW ALSO DEVELOPS NEWD FROM W OF
CENTRAL CA COAST INTO SRN OR BY THIS AFTERNOON. PAC FRONT HAS MOVED
INLAND AND AT 12Z LOCATED FROM SFO BAY AREA SSEWD TO E OF COASTAL
RANGE AND OFFSHORE JUST W OF LAX.

THE VERY STRONG LOW LEVEL SLY FLOW AND GENERAL PCPN COASTAL AREAS IN
ADVANCE OF FRONT WILL TEMPORARY DIMINISH THIS AM AS FRONT CONTINUES
EWD. HOWEVER THE MID LEVEL COOLING AND STRONG ASCENT AHEAD OF
APPROACHING UPPER LOW WILL STEEPEN LAPSE RATES AND INCREASE
INSTABILITY ALONG CENTRAL/SRN CA COASTAL AREAS BY MID DAY. WITH SFC
DEWPOINTS REMAINING IN THE LOW 50S SBCAPES COULD CLIMB TO 500-800
J/KG BY 18Z AS TEMPS WARM TO NEAR 60F IN COASTAL AREAS.

MODEL SOUNDINGS SUGGEST THAT SHEAR WILL BECOME INCREASINGLY
FAVORABLE FOR LOW TOPPED SUPERCELLS BY EARLY AFTERNOON AS 850MB
WINDS INCREASE AHEAD OF UPPER LOW. WITH SFC-1KM SHEAR OF 30KT AND
60-70 KT OF DEEP LAYER SHEAR...HODOGRAPHS INDICATE HELICITIES OF
200-300 M2/S2. THUNDERSTORMS SHOULD SPREAD/DEVELOP INLAND CENTRAL
AND NRN PORTION SRN CA COASTAL AREAS BY MID DAY. ALONG WITH
POTENTIAL FOR HAIL AND LOCALLY STRONG/DAMAGING
WINDS...WATERSPOUTS/ISOLATED TORNADOES WILL BE POSSIBLE THROUGH
EARLY EVENING. THREAT OF SEVERE SHOULD END BY SHORTLY AFTER 00Z WHEN
SHEAR RELAXES AS UPPER LOW OPENS INTO A TR0UGH AND MOVES INLAND.

.HALES.. 01/27/2008

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