EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 320 AM PDT TUE APR 11 2000
...SYNOPSIS...
WEAK HIGH PRESSURE ALOFT AND WEAK OFFSHORE LOW LEVEL FLOW WILL BRING
WARMING TO SOUTHWEST CALIFORNIA TODAY AND WEDNESDAY. A WEAK COASTAL
EDDY WILL BRING LOW CLOUDS AND PATCHY DENSE FOG TO THE COAST THIS
MORNING. AS A TROUGH OF LOW PRESSURE OVER THE EASTERN PACIFIC MOVES
CLOSER TO THE CALIFORNIA COAST DURING THE LAST HALF OF THE WEEK...A
COOLING TREND WILL DEVELOP WITH BREEZY CONDITIONS IN THE MOUNTAINS
AND DESERTS AND MORE EXTENSIVE AND PERSISTENT COASTAL LOW CLOUDS.
...DISCUSSION...
00Z NCEP MDLS STILL TRICKLING IN FOLLOWING EARLIER PROBLEMS WITH THE
IBM SUPERCOMPUTER. FOR TODAY...EARLY MON EVENING ACARS SOUNDINGS
SHOWED THE BASE OF THE MARINE INVERSION HAD LOWERED TO BETWEEN 500
AND 1000 FT. LATEST SURFACE OBSERVATIONS AND SATELLITE IMAGERY
SUGGEST THE INVERSION BASE IS NR 1000 FT. THIS SHOULD CHANGE LTL THE
NEXT 24 TO 36 HOURS WITH MAINLY DIURNAL FLUCTUATIONS. WK CSTL EDDY
HAS DEVELOPED AS SUGGESTED BY LAST NIGHT'S ETA...THE RUC...AND
12Z AND 00Z RUNS OF THE AVN. LOW CLOUDS SHOULD BE CONFINED
TO THE CSTL STRIP THIS MORNING FM SRN LOS ANGELES COUNTY S WITH
LCLLY DENSE FOG POSSIBLE ON THE ORANGE COUNTY CSTL PLAIN NR HIGHER
TERRAIN AND NR THE MESAS OF SAN COUNTY. KSOX AND KNKX 88D VAD WINDS
SHOW LOW LVL ELY FLOW OF 15-20 KT. WHILE OFSHR WINDS FOR VLYS SHOULD
BE LIMITED... MAIN EFFECT OF WK LOW LVL ELY FLOW WL BE TO DELAY THE
SEA BREEZE TODAY. THIS...IN COMBINATION WITH THE LWR AND STRONG
MARINE INVERSION...SHOULD ALLOW TEMPERATURES TO WARM SIGNIFICANTLY
TODAY IN THE VLYS AND INLAND CSTL SXNS. LTL CHANGE FOR WED AS
HEIGHTS CHANGE LTL...EXCEPT MINOR COOLING WL SPREAD INLAND SOMEWHAT
FM THE IMMEDIATE CST AS WK INTERIOR OFSHR FLOW WKNS AND WK ONSHR
FLOW DEVELOPS. COOLING WL SPREAD FARTHER INLAND THU WITH BREEZY
CONDITIONS DEVELOPING IN THE NRN DESERTS AND MTNS WITH MAIN
DEEPENING OF MARINE LYR FOR SW CA BEGINNING THU NIGHT.
EXTENDED...NEW MRF STILL NOT IN...BUT EXTENDED GUIDANCE SUPPORTS
COOLER AND BREEZY WITH A DEEPER MARINE LYR FOR SW CA FRI AND SAT
WITH ANY RAIN REMAINING N OF SW CA. BY SUN INTO EARLY NEXT WEEK SOME
DIFFERENCES BEGIN TO ARISE IN THE EXTENDED MDLS...BUT ALL MDLS ARE
IN GENERAL AGREEMENT WITH A DEEP UPR TROUGH ALG THE W CST.
SAN 000
.SAN...NONE.
MARTIN