EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 310 AM PDT THU APR 20 2000
...SYNOPSIS...
A WEAK COASTAL EDDY WILL BRING PATCHY LOW CLOUDS AND FOG TO THE
COAST THIS MORNING...OTHERWISE MOSTLY SUNNY AND WARMER FOR MOST OF
SOUTHWEST CALIFORNIA TODAY. A WEAK UPPER LEVEL LOW PRESSURE SYSTEM
WILL MOVE TO NEAR THE SOUTHWEST CALIFORNIA COAST FRIDAY
AFTERNOON...AND EAST INTO ARIZONA LATE FRIDAY NIGHT AND SATURDAY
BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS TO SOUTHWEST
CALIFORNIA FRIDAY AFTERNOON AND NIGHT. DRY AND WARMER FOR THE
WEEKEND.
...DISCUSSION...
ECMWF STILL PREFERRED THROUGH THE SHORT RANGE WITH AVN SIMILAR
BEYOND 24 HOURS. WK CSTL EDDY SHOULD BRING PATCHY LOW CLOUDS AND FOG
TO THE CST THIS MORNING. EARLY WED EVENING ACARS SOUNDING SHOWED THE
INVERSION BASE AROUND 600 FEET LGB TO 1200 FEET SAN. FOG COULD BE
LCLLY DENSE NR HIGHER TERRAIN IN ORANGE COUNTY IF THE STRATUS MOVS
SUFFICIENTLY INLAND. OTHERWISE...MOSTLY SUNNY AND WARMER
TODAY...ESPECIALLY INLAND AS WK NELY LOW LVL FLOW AND A
STRENGTHENING AND LWRG MARINE INVERSION RESULTS IN HIGH TEMPERATURE
FOR THE INLAND VLYS...MTNS...AND DESERTS 5 TO 7 DEGREES WARMER THAN
WED.
TONIGHT...CSTL EDDY SHOULD BRING MORE EXTENSIVE STRATUS WITH GREATER
INLAND PENETRATION OVERNIGHT. MID LVL COLD POOL WITH THE UPR LOW
PROGGED TO BE ALG THE SW CA CST FM LAX TO SAN FRI AFTERNOON...MOVG
INLAND FRI EVENING. EVEN WITH MDLS SHOWING SYS TO BE MSTR
STARVED...THIS TRACK WOULD BE SUFFICENT TO BRING SCT SHOWERS AND
WDLY SCT THUNDERSTORMS TO CST/VLYS/MTNS FRI AFTERNOON INTO FRI
EVENING...AND MTNS/DESERTS FRI EVENING AND NIGHT WITH CLEARING AND
WARMER FOR SAT. BEST CHANCE FOR MEASURABLE PRECIPATION FOR MOST
AREAS WL BE LATE FRI AFTERNOON THRU FRI NIGHT.
EXTENDED...MDLS IN LESS THAN PERFECT AGREEMENT WITH SHORTWAVE
TIMING...BUT HAVE DEAMPLIFIED FLOW ALG THE W CST SAT THRU
MON...GENERALLY FAIR FOR SW CA...LCLLY BREEZY IN MTNS/DESERTS...DAY
TO DAY TEMPERATURE/MARINE LYR TRENDS SUBJECT TO CHANGE BASED ON
SHORTWAVE TIMING.
SAN 002
.SAN...NONE.
MARTIN