Saturday, November 20, 2010

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 201953
SWODY1
SPC AC 201952

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0152 PM CST SAT NOV 20 2010

VALID 202000Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...NRN CA...
SATELLITE IMAGERY SHOWS STRONG LIFT AHEAD OF SWD MOVING UPPER LOW
JUST OFF THE NRN CA COAST. AS LIFT AND COOLING ALOFT SHIFT
SWD...ISOLATED THUNDERSTORMS SHOULD MOVE INTO THE BAY AREA BY 00Z
AND INTO PORTIONS OF THE SACRAMENTO VALLEY THIS EVENING. MODELS
INDICATE DEEP TROPOSPHERIC LIFT WILL INCREASE IN INTENSITY LATER
TODAY...WITH A CORRESPONDING INCREASE IN CONVECTIVE ACTIVITY LIKELY.
A FEW CELLS MAY BE STRONG WITH LOCALLY GUSTY WINDS. FURTHER...BACKED
LOW LEVEL WINDS AHEAD OF THE COLD FRONT AND STRONG DEEP LAYER SHEAR
MAY RESULT IN ROTATION IN SOME CELLS. HOWEVER...GIVEN A GRADUALLY
COOLING BOUNDARY LAYER AFTER SUNSET...THE SEVERE THREAT APPEARS TOO
LOW FOR OUTLOOK PROBABILITIES...WITH EFFECTIVE PARCEL LEVELS
BECOMING SLIGHTLY ELEVATED INTERIOR VALLEYS.

..JEWELL.. 11/20/2010

.PREV DISCUSSION... /ISSUED 0939 AM CST SAT NOV 20 2010/

AN UPPER LOW OFF THE PACIFIC NW COAST WILL MOVE SWD INTO NRN CA BY
SUNDAY MORNING. A LEAD SHORTWAVE TROUGH OVER CNTRL/SRN COASTAL CA
WILL TRANSLATE EWD INTO THE SRN PORTIONS OF THE GREAT BASIN BY THIS
EVENING. AT THE SURFACE...A COLD FRONT WILL PUSH EWD THROUGH NV AND
SRN CA AND INTO THE LOWER CO RIVER VALLEY BY DAYBREAK SUNDAY. ISOLD
TSTM ACTIVITY APPEARS MOST PROBABLE NEAR AND OFFSHORE THE CNTRL CA
TO SRN ORE COAST DURING THE DAY AND THEN FARTHER INLAND INTO PARTS
OF CNTRL CA DURING THE LATTER HALF OF THE PERIOD AS STEEPENING MID
LEVEL LAPSE RATES /-25 TO -30 DEG C AT H5/ YIELD WEAK BUOYANCY.
FARTHER SE OVER THE CO RIVER VALLEY...INCREASING LARGE SCALE ASCENT
ATTENDANT TO THE APPROACHING UPPER TROUGH AND THE NOSE OF A MOISTURE
PLUME EMANATING FROM THE ERN PACIFIC MAY WORK IN CONCERT TO SUPPORT
A FEW THUNDERSTORMS MAINLY THIS EVENING INTO THE OVERNIGHT HOURS.

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