EXTREME SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSAN 900 AM PST SUN MAR 18 2001
...SYNOPSIS...
HIGH PRESSURE ALOFT WILL BRING WARM WEATHER...ESPECIALLY INLAND.
SKIES WILL BE MOSTLY CLEAR...EXCEPT FOR PATCHY LOW CLOUDS AND FOG AT
THE COAST AT TIMES...MAINLY THIS MORNING. COOLING AND INCREASING
CLOUDS WILL OCCUR LATER IN THE WEEK AS ONSHORE FLOW DEVELOPS.
...DISCUSSION...
LOCALLY DENSE FOG OCCURRED THIS MORNING AS THE MARINE LAYER HAS
BECOME SHALLOW AT ABOUT 1000 FEET DEEP. PRESSURE GRADIENTS ARE
TRENDING OFFSHORE THIS MORNING...BUT TO THE EAST IT IS STILL ABOUT
+1 MB ONSHORE TO THE DESERTS. THE THICK HAZE IS CLEARING RAPIDLY
OVER INLAND AREAS...SO THOSE AREAS APPEAR TO BE BREAKING THE
INVERSION AND THUS SHOULD WARM INTO THE LOWER 80S...WHICH IS NEAR
THE ADIABATIC LAPSE RATE POTENTIAL...BASED ON ACARS SOUNDINGS. NEAR
THE COAST...THE COLD SST VALUES AND AN EXPECTED SEA BREEZE SHOULD
KEEP TEMPS GENERALLY BELOW MOS VALUES...THOUGH 12Z AVN/NGM MOS TEMPS
ARE LOWER THAN PREVIOUS MOS VALUES FOR TODAY.
12Z MSO AND 00Z COAMPS INDICATE THAT THE LOW-LEVEL OFFSHORE FLOW
SHOULD BE ENOUGH TO KEEP THE LOW CLOUDS/FOG AWAY TONIGHT...THOUGH
REALISTICALLY...WE WILL STILL PROBABLY BE MOIST ENOUGH FOR SOME
IMMEDIATE-COAST AND COASTAL-WATERS FOG. HOWEVER...IF THE OFFSHORE
FLOW MAKES IT CLOSER TO THE COAST THAN EXPECTED...THEN THAT WOULD
CHANGE. AN EDDY APPEARS FAIRLY UNLIKELY TONIGHT...SO FOG SHOULD BE
SOMEWHAT MINIMAL.
MONDAY APPEARS TO BE THE WARMEST DAY OVERALL. TUESDAY SHOULD BE A
BIT MORE ONSHORE...SO COASTAL AREAS SHOULD COOL SLIGHTLY WITH A
SLIGHT INCREASE IN LOW CLOUDS AND FOG. MTN/DESERT TEMPS SHOULD NOT
DROP UNTIL ABOUT THU/FRI WHEN THE HEIGHTS/TEMPS ALOFT DECREASE DUE
TO THE STRONGER WEST FLOW AND EROSION OF THE HIGH. MODELS ARE
VARYING A LOT WITH THE SOLUTIONS FOR NEXT WEEKEND...BUT THE TROUGH
THAT THE MRF FROM FRIDAY NIGHT HAD WILL PROBABLY BE WEAK IF IT
OCCURS...SO PRECIP LOOKS UNLIKELY...OTHER THAN POSSIBLY MARINE LAYER
DRIZZLE.
A QUICK ZONE UPDATE WILL BE ISSUED SHORTLY.
SAN 000
.SAN...NONE.
MAXWELL