Drought in California, February 28, 2001

INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA
850 PM PST TUE FEB 27 2001

THE PERSISTENT UPPER LOW WHICH HAS LINGERED NEAR SOCAL OVER THE PAST
SEVERAL DAYS IS FINALLY MOVING INLAND NEAR THE CA/MEXICO BORDER...
ONLY TO BE REPLACED BY ANOTHER CUTOFF MOVING INTO CENTRAL CA WED.
THIS IS AN UNUSUAL EVOLUTION AS SHORT WAVE ENERGY FROM THE NORTHERN
STREAM HAS BECOME WRAPPED UP INTO THE SOCAL LOW/S CIRCULATION...THE
TWO WAVES ROTATE AROUND EACH OTHER/S CONCENTRIC AXIS TONIGHT/WED IN
A FUJIWARA PATTERN. RARE TO SEE SIGNIFICANT PVA/STRONG CYCLONIC FLOW
ALOFT RETROGRADING INTO CA 'BACKDOOR' STYLE FROM THE NORTHERN GREAT
BASIN. MODELS HAVE WAFFLED A LITTLE ON EXACT TRACK OF THE UPPER
CORE. EARLIER 12Z RUNS HAD TRENDED WEST TOWARDS CNTRL CA COAST WED
AFTN...HOWEVER 00Z PROGS INDICATE SIMILAR POSITIONS AS LAST NIGHTS
00Z WITH COLD CORE DIRECTLY OVER THE SAN JOAQUIN VLLY TOMORROW AFTN.

THE BIG UPCOMING FORECAST CONCERN WILL BE THE THREAT OF CONVECTION
WITH HAIL AND POTENTIAL LARGE HAIL ON WED AFTN AS LAPSE RATES BECOME
QUITE STEEP UNDERNEATH THE COLD UPPER LOW CENTER. AVN DEPICTS H5 TEMPS
AS LOW AS -27C...AND THE LACK OF SIGNIFICANT CLOUD COVER WILL ALLOW
FOR AMPLE SFC INSOLATION AND HTNG TO INCREASE INSTABILITY FURTHER.
ETA/MESOETA PROGGED CAPES ARE IN 400-650 J/KG RANGE...WUD NOT BE
SURPRISED TO SEE 06Z TREND HIER ON THESE NUMBERS. SHEAR WL BE WEAK.

EXPECT THE MOST FAVORABLE COMBINATION OF MSTR/LIFT FROM FRESNO
COUNTY SOUTH TO KERN COUNTY WITH LOCAL TERRAIN UPSLOPE/SFC MSTR
CONVERGENCE PROBABLY BRINGING INITIAL DEVELOPMENT IN COASTAL RANGE
AND SIERRA FOOTHILLS 3-6KFT...THEN EXTENDING INTO SAN JOAQUIN VLLY
MAINLY S OF FRESNO WITH TIME. STEERING FLOW BASED ON UPPER LOW MOVMT
SHOULD BE SSW/SW 10KTS.

IN THE NEAR TERM THIS EVENING...THE COMBINATION OF AN INITIAL SHORT
WAVE MOVING SW TOWARDS PT CONCEPTION AND SOUTHERN UPPER LOW KICKING
INLAND RESULTS IN SOME MSTR CONVERGENCE AND LIFT NEAR S/SE END OF
CWA. SHOWERS AND ISOL TSTMS...WHICH FORMED THIS AFTN WHERE BEST MSTR
AND LIFT WERE PRESENT...CONTINUE TO PERSIST WELL BEYOND SUNSET WITH
THE ADDITIONAL SUPPORT OF THESE DYNAMICS. WITH CONTINUED LOSS OF
HTNG AND AVBL POTENTIAL ENERGY...EXPECT LINGERING ACTIVITY TO BE
NEARLY DIMINISHED BY 06Z.

PLAN A FEW WORDING ADJUSTMENTS...WILL DROP SOME FCST MIN TEMPS AND
MINOR UPDATE TO )FOLLOW.

.HNX...NONE.

LAVIS