EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 930 AM PDT MON MAY 15 2000
...SYNOPSIS...
AN APPROACHING COLD FRONT WILL BRING INCREASING CLOUDS...WINDS AND
COOLING TODAY AND TUESDAY. THERE IS A SLIGHT CHANCE OF SHOWERS OR
THUNDERSTORMS LATE TONIGHT AND TUESDAY. PRECIPITATION AMOUNTS ARE
EXPECTED TO AVERAGE LESS THAN A TENTH OF AN INCH. BUILDING HIGH
PRESSURE WILL RESULT IN A GRADUAL WARMING TREND DURING THE SECOND
HALF OF THE WEEK.
...DISCUSSION...
THE KOAK AND KREV 15/12Z RAOBS SHOWED 500 MB TEMPERATURES -20
DEGREES CELSIUS AND THIS WAS PRIOR TO THE COLD CORE MOVING ONSHORE.
PREVIOUS STUDIES/EXPERIENCE INDICATE THAT UPDRAFTS HAVE TO REACH
THIS LEVEL TO SUPPORT ICE CRYSTALS/FAVORABLE CONDITIONS FOR
LIGHTNING. ASSUMING PERFECT MODEL FORECASTING...THE -20 DEGREE
ISOTHERM NICKS ORANGE/SW SAN BERNARDINO/N RIVERSIDE COUNTIES AFTER
16/09Z. CAPE VALUES ARE RATHER SMALL BUT DO INCREASE TO 90+
JOULES/KILOGRAM AFTER 16/15Z-16/21Z...LATEST AVAILABLE MESOETA TIME.
CURRENT FORECAST MAX TEMPERATURES IN THE UPPER 60S
SUPPORT REACHING 500 MB LEVEL...OROGRAPHICS AND DIVERGENCE ALOFT ARE
SLIGHTLY OUT OF PHASE AS WIND BECOMES MORE WESTERLY...AND JET CORE
PULLS AWAY. NONETHELESS ALREADY HAVE TSTMS FORECAST FOR THESE AREAS
SO WILL LEAVE IN. STILL WATCHING WIND SITUATION CLOSELY. PRESSURE
GRADIENTS ONLY +7 MB KSAN-KTPH AT THIS TIME AND HIGHEST WIND GUST
FROM RAWS STATIONS 24 MPH AT RANCHITA IN THE SAN DIEGO MOUNTAINS.
KNKX SOUNDING AND LATEST ACARS SHOW THE SW WINDS +25 KTS ARE DOWN TO
6000 FEET. LOOKS LIKE WE MIGHT MAKE IT THROUGH THE AFTERNOON BEFORE
HAVING TO ISSUE WIND ADVISORIES/SMALL CRAFT WARNINGS...SO NO UPDATES PLANNED
FOR REMAINDER OF MORNING.
MEDIUM RANGE MODELS CONTINUE IN GOOD AGREEMENT..SO WARM UP WITH
RIDGING LAST HALF OF THE WEEK STILL OKAY.
SAN 012
.SAN...NONE.
BALFOUR