Wildfire in California, June 19, 2001

EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
930 AM PDT TUE JUN 19 2001

                             ...SYNOPSIS...
HOT...DRY CONDITIONS WILL CONTINUE THIS WEEK AS HIGH PRESSURE ALOFT
DOMINATES THE WEATHER OVER THE SOUTHWESTERN UNITED STATES. ONSHORE
BREEZES AND THE MARINE LAYER WILL KEEP MORE COMFORTABLE CONDITIONS
NEAR THE COAST...ALONG WITH AREAS OF NIGHT AND MORNING LOW CLOUDS
AND FOG. AFTERNOON CLOUDS WILL DEVELOP OVER THE MOUNTAINS AND
DESERTS AS MOISTURE MOVES UP FROM THE SOUTHEAST.

                            ...DISCUSSION...
THOUGH HOT TEMPERATURES ARE MAIN CONCERN...AN INCREASING THREAT
IS THE MOISTURE TO THE SOUTH AND SOUTHEAST. DEWPOINTS ARE UP 20+
DEGREES OVER IMPERIAL/EASTERN SAN DIEGO/EASTERN RIVERSIDE COUNTIES.
00Z MODELS DID NOT CATCH THIS AND/OR WERE ABOUT 24 HOURS SLOWER ON
ITS OCCURRENCE. 06Z MESOETA ALSO SLOW IN INCREASING LOW LEVEL
MOISTURE...BUT DID SHOW SUSTAINED SOUTHERLY WINDS THROUGH THIS AREA.
12Z MODEL GUIDANCE WILL BE DELAYED TODAY DUE TO THE NCEP BACKUP
PROCESSING TEST. VAD WINDS FROM KYUX SHOW S-SE 20 KTS THROUGH LOWER
4000 FEET. ABOVE THIS LEVEL AND TO THE WEST OF THE SW CALIFORNIA
MTNS THE MEAN FLOW IS STILL OUT OF THE WEST AND THIS SHOULD ACT TO
SUPPRESS THUNDERSTORM DEVELOPMENT OVER EASTERN CWFA TODAY WITH
LOW/MID LEVEL CONVERGENCE ZONE CLOSER TO THE COLORADO RIVER VALLEY.
STILL HAVE TO FACTOR IN INCREASED HUMIDITY OVER DESERT ZONES. WITH
FORECAST MAX TEMPS...HEAT INDICES WILL BE CLOSE OR SLIGHTLY ABOVE
THRESHOLD FOR HEAT ADVISORIES. INCREASED HEAT CAPACITY OF AIR MASS
MAY SHAVE A FEW DEGREES AS WOULD ANY REDUCTION OF SOLAR HEATING DUE
TO CUMULUS DEVELOPMENT...YIELDING HEAT INDICES SLIGHTLY BELOW
THRESHOLD 115 DEGREES. FOR NOW HOLD OFF ON ISSUING HEAT ADVISORY. IN
ANOTHER MORNING UPDATE WILL INCLUDE MENTION OF HUMID CONDITIONS
OVER DESERTS AS WELL AS AFTERNOON CLOUDS DESERTS/MOUNTAINS...AND
RAISE TEMPERATURES WEST OF THE MOUNTAINS TO REFLECT ABOUT 3 DEGREES
WARMING OVER MONDAY.

LOOKING FURTHER AHEAD...THE SATELLITE WATER VAPOR IMAGERY LOOP SHOWS
DEFINITE THINNING OF THE SUBTROPICAL HIGH CELL OVER S CALIFORNIA.
THIS SUPPORTS THE 00Z MODEL TREND OF SPLITTING OF THE HIGH CELL BY
WEDNESDAY EVENING. THIS SOLUTION WAS DERIVED FROM WEAK SHORT WAVE
DROPPING SE THROUGH CENTRAL CALIFORNIA AND ANOTHER EASTERLY
WAVE/MESOSCALE CONVECTIVE COMPLEX MOVING ACROSS N/CENTRAL BAJA
PENINSULA. A QUASI-STATIONARY COL CENTER THEN FORMS NEAR 30N 120W
THAT PERSISTS THROUGH FRIDAY....AFTER WHICH THE DOMINATE HIGH CELL
IS CENTERED OVER THE FOUR CORNERS AREA. RESULTING SYNOPTIC PATTERN
SUPPORTS CONTINUED NORTHWEST TO NORTHWARD TRANSPORT OF MOIST
TROPICAL AIR TOWARDS IF NOT OVER CWFA. IN THE AFTERNOON PACKAGE
WEDNESDAY THROUGH DAY 7 WILL SHOW INCREASING AFTERNOON/EVENING
CLOUDS/THREAT OF SHOWERS/TSTMS MTNS AND DESERTS.

SAN 000

.SAN...NONE.

BALFOUR