DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 270532
SWODY1
SPC AC 270529

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 PM CST SAT JAN 26 2008

VALID 271200Z - 281200Z

..THERE IS A SLGT RISK OF SVR TSTMS ALONG THE S CNTRL THROUGH SRN
CA COASTAL AREAS...

..SYNOPSIS...

PROGRESSIVE UPPER PATTERN WILL EXIST SUNDAY. UPPER TROUGH OVER THE
ERN U.S. WILL MOVE OFFSHORE...WHILE AN UPPER RIDGE BUILDS OVER THE
PLAINS AND MS VALLEY DURING THE DAY AND INTO THE ERN U.S. OVERNIGHT.
FARTHER WEST...AN UPPER TROUGH IS FORECAST TO AMPLIFY SWD THROUGH
THE PACIFIC NW WHILE UPPER LOW OVER THE ERN PACIFIC EJECTS NEWD
THROUGH CA AND THE GREAT BASIN REGION.

..S CNTRL THROUGH SRN CA COASTAL AREA...

A SERIES OF VORTICITY MAXIMA WILL ROTATE THROUGH UPPER TROUGH THAT
IS NOW SITUATED OFF THE CA COAST AS IT ADVANCES EWD INTO CNTRL AND
SRN CA. CURRENT WV IMAGERY SHOWS A STRONG SHORTWAVE TROUGH LIFTING
NEWD INTO THE CNTRL CA COAST. IN WAKE OF THIS IMPULSE...A MID TO
UPPER LEVEL DRY SLOT WILL SPREAD INTO CNTRL AND SRN CA BY EARLY
SUNDAY...AND THIS MIGHT IMPROVE THE CHANCE FOR SOME OF THE LOW
CLOUDS TO MIX OUT DURING THE DAY. A SECONDARY VORTICITY MAXIMA WILL
ROTATE THROUGH THE BASE OF THE UPPER TROUGH AND INTO THIS REGION BY
LATE SUNDAY AFTERNOON. THIS FEATURE WILL BE ACCOMPANIED BY COLD AIR
ALOFT...-25 TO -27C AT 500 MB AND STEEP LAPSE RATES. THIS WILL
RESULT IN DESTABILIZATION...ESPECIALLY NEAR THE COASTAL AREAS WHERE
ONSHORE FLOW WILL CONTRIBUTE TO DEWPOINTS IN THE 40S TO NEAR 50.
MLCAPE FROM 500-800 J/KB WILL BE POSSIBLE IF SUFFICIENT BOUNDARY
LAYER WARMING OCCURS. HOWEVER...COLD ADVECTION ALOFT WILL PROMOTE
SOME DESTABILIZATION...EVEN IF MINIMAL HEATING OCCURS. MODERATE TO
STRONG LOW-MID LEVEL WINDS WILL ACCOMPANY THE SHORTWAVE TROUGH WITH
BULK SHEAR AND LOW LEVEL HODOGRAPHS SUPPORTIVE OF ORGANIZED STORM
STRUCTURES. INCREASING ASCENT AND DESTABILIZATION SHOULD PROMOTE AN
INCREASE IN SURFACE BASED THUNDERSTORMS ALONG AND JUST INLAND OF THE
CNTRL AND SRN CA COASTS BY LATE AFTERNOON. PRIMARY THREATS WILL BE
LOW TOPPED SUPERCELLS CAPABLE OF PRODUCING LARGE HAIL AND ISOLATED
TORNADOES THROUGH EARLY EVENING.

.DIAL.. 01/27/2008

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