Damaging Wind in California, April 20, 2001

SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
915 PM FRI APR 20 2001

WATER VAPOR IMAGERY INDICATED UPR LOW OFF THE CST OF CNTRL CA THIS
EVENING MOVING SSEWD. MAIN FRONTAL BAND WAS PUSHING ACRS SLO AND NWRN
SBA COUNTIES ATTM. HWVR...SUFFICIENT LOW LVL MSTR AND DYNAMIC LIFT
ASSOCD WITH RAPIDLY FALLING HGTS AHEAD OF THE UPR LOW HAS ALLOWED
PLENTY OF SHWR ACTIVITY TO DVLP AHEAD OF THE FRONTAL BAND...WITH SHWRS
CURRENTLY OCCURRING ACRS MUCH OF THE FCST AREA. SOME OF THE SHWRS WERE
LCLLY HVY...ESPECIALLY THOSE IN THE VICINITY OF THE MAIN FRONTAL BAND.
MANY LOCATIONS IN SLO CNTY REPORTED A BRIEF PERIOD OF STG WNDS...WITH
WND GUSTS TO BETWEEN 40 AND 50 MPH FOR AN HOUR OR SO ALG THE LEADING
EDGE OF THE FRONTAL BAND. MAIN FRONTAL BAND SHOULD PRODUCE A 2 TO 4 HR
PERIOD OF MORE CONCENTRATED MODERATE TO HEAVY SHOWER ACITIVITY AND SOME
GUSTY WINDS AS IT SWEEPS ACRS THE FCST AREA TONIGHT...ALTHOUGH IT MAY
LOSE SOME OF ITS PUNCH AS IT PUSHES S OF PT CONCEPTION.

UPR LOW IS PROGGED TO PUSH INLAND ACRS THE SRN SAN JOAQUIN VLY
OVERNIGHT...REACHING THE SERN DSRTS BY MID MORNING SAT. MAIN FRONTAL
BAND SHOULD EXIT SLO COUNTY BY MIDNIGHT...AND PROBABLY PUSH ACRS MOST
OF L.A. CNTY BEFORE DAYBREAK ON SAT. HWVR...VERY STRONG VORT IS PROGGED
TO ROTATE AROUND THE SRN SIDE OF THE UPR LOW AND ACRS THE FCST AREA AS
THE UPR CNTR PUSHES INLAND. THIS WL KEEP SCT SHWRS CONTG ACRS THE FCST
AREA FOR SEVERAL HRS BEHIND THE MAIN FRONT. ALTHOUGH MOST OF THE TSTM
ACTIVITY HAS REMAINED TO THE N OF THE FCST AREA...BLV THERE IS AT LEAST
A SLGT THREAT OF TSTMS AS COOLING ALF OCCURS LATER TONIGHT...AND STRONG
VORT APCHS THE AREA. RAINFALL TOTALS SHOULD AVERAGE BETWEEN ONE QUARTER
OF AN INCH AND ONE HALF INCH IN MOST AREAS...WITH LOCAL TOTALS APCHG
ONE INCH IN THE FOOTHILLS AND MTNS.

SHWRS SHOULD END IN MOST AREAS BY MID MORNING ON SAT AS DECENT
SUBSIDENCE AND STG AND INCRGLY DRY NWLY FLOW SPRDS ACRS THE FCST AREA
ON THE WRN SIDE OF THE UPR LOW. UPR SUPPORT WL BE FAVORABLE FOR
ADVISORY LVL WNDS ACRS PORTIONS OF THE AREA ON SAT...PARTICULARLY ACRS
THE MTNS...ALG THE CNTRL CST OF SLO/WRN SBA COUNTIES...BLO PASSES AND
CYNS ON THE S CST OF SBA CNTY...AND POSSIBLY IN THE VLYS OF L.A. CNTY.

IN THE MTNS...SNOW LVLS SHOULD LOWER TO BETWEEN 3000 AND 4000 FT
OVERNIGHT. AM TEMPTED TO BUMP WINTER WEATHER ADVISORY TO A WINTER STORM
WARNING BASED UPON THE AMT OF SHOWER ACITIVITY ALREADY OCCURRING...BUT
IT WL BE A RATHER QUICK MOVER...WHICH MAY KEEP AMTS TO WINTER WEATHER
ADVISORY LVLS. MOST OF THE SHWR ACITIVITY IS XPCTD TO END ACRS THE MTNS
BY MID MORNING SAT...BUT COULD LINGER INTO EARLY AFTERNOON ON THE NRN
SLOPES.

AS THE UPR LOW MOVES RATHER QUICKLY TO THE E OF THE FCST AREA SAT NIGHT
AND SUN...UPR RDG WL BUILD INTO THE W CST...AND THICKNESSES/H85 TEMPS
WL REBOUND DRAMATICALLY. XPCT MAX TEMPS TO FOLLOW SUIT...WITH MANY
LOCATIONS ACRS THE FCST AREA LIKELY EXPERIENCING 8 TO 15 DEGS OF
WARMING BETWEEN SAT AND SUN. SOME LOCATIONS IN THE MTNS MAY WARM BY
MORE THAN 20 DEGS. UPR RDG SHOULD HOLD ACRS THE FCST AREA THROUGH
TUE OR WED...FOR ABV NORMAL TEMPS...AND PLENTY OF SUNSHINE. DO NOT
XPCT MUCH IN THE WAY OF LOW CLDS ACRS CSTL SXNS BEFORE TUE OR WED.
ANOTHER TROUGH DVLPG ACRS THE PAC MAY BRING A RETURN TO COOLER
WEATHER BY THE END OF NEXT WEEK.

LAX +400. BRUNO.

.LAX...WINTER WEATHER ADVISORY (SEE LAXWSWLAX).
 a      SMALL CRAFT ADVISORY (SEE LAXCWFLAX).