DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 071956
SWODY1
SPC AC 071953

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0253 PM CDT TUE APR 07 2009

VALID 072000Z - 081200Z

...NO SVR TSTM AREAS FORECAST...

-- UPDATE --
...CA...
VIS IMAGERY INDICATES BAROCLINIC CLOUD/PRECIP BAND MOVING INLAND
FROM MUCH OF CENTRAL/NRN CA COAST ATTM. CLOUD/CONVECTIVE TRENDS
WITH OFFSHORE/COLD-CORE ACTIVITY INDICATE REGIME OF STRONGEST
POST-FRONTAL/LARGE-SCALE ASCENT WILL MOVE INLAND FROM MRY AREA
NWD...LATE THIS AFTERNOON THROUGH EARLY EVENING...THEN OVER SRN SAC
VALLEY AND NRN SAN JOAQUIN VALLEY. GIVEN THAT FACTOR...ALONG WITH
DRYNESS OF AIR MASS AND LACK OF SUBSTANTIAL CONVECTIVE-SCALE FORCING
FARTHER S...SRN PART OF AOA 10-PERCENT TSTM RISK ACCORDINGLY HAS
BEEN ADJUSTED NWD.

..EDWARDS.. 04/07/2009

.PREV DISCUSSION... /ISSUED 1112 AM CDT TUE APR 07 2009/

...CA...
MORNING WV IMAGERY DEPICTS A CLOSED UPR LOW POSITIONED OFF THE COAST
OF CA...WITH A SURFACE COLD FRONT IDENTIFIED IN RECENT VIS SATELLITE
LOOP POISED TO ENTER THE CENTRAL COAST BY LATE MORNING. AS THE
FRONTAL BOUNDARY AND UPR LVL LOW MOVE EAST ACROSS THE REGION...A
COLD MID LVL AIRMASS /AOB -20 DEG C/ WILL ENTER THE REGION...WHICH
WILL BE ACCOMPANIED BY A S/W TROUGH...FAVORING AN INCREASE IN
THUNDERSTORM COVERAGE BY LATE AFTERNOON ALONG AND W OF A SAC TO BFL
LINE. THE COLD UPR AIR WILL AID IN STEEPENING LAPSE RATES /AUGMENTED
BY AFTERNOON SURFACE HEATING/...CONTRIBUTING TO MODEST MUCAPE VALUES
GENERALLY LESS THAN 700 J/KG. FAST...MAINLY UNIDIRECTIONAL MID/UPR
LVL FLOW IS CURRENTLY OBSERVED IN AREA VAD WIND PROFILE
DATA...YIELDING FAVORABLE DEEP LAYER SHEAR FOR ORGANIZED
THUNDERSTORMS. HOWEVER...FLOW ALOFT IS FORECAST TO GRADUALLY WEAKEN
AS THE UPR LOW APPROACHES...RESULTING IN MINIMAL SHEAR FOR SEVERE
STORMS AS THE ATMOSPHERE DESTABILIZES. THE LOW FREEZING LEVEL/COLD
MID LVL TEMPERATURES...AND STEEP LAPSE RATE ENVIRONMENT WILL LIKELY
SUPPORT SMALL HAIL IN THE STRONGER STORMS...BUT SHOULD REMAIN BELOW
SEVERE LEVELS.

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