754 
FPUS66 KSAN 081011
AFDSAN

SOUTHWESTERN CALIFORNIA AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
310 AM PDT MON SEP 8 1997

                         ...SYNOPSIS...
STRONG HIGH PRESSURE OVER THE SOUTHWEST U.S. WILL CONTINUE THE WARM
SUMMER WEATHER THROUGH TUESDAY. A MOIST SOUTHEAST FLOW ALOFT WILL 
INCREASE THE CHANCE OF AFTERNOON THUNDERSTORMS IN THE MOUNTAINS AND
DESERTS. 

                        ...DISCUSSION...
RAMSDIS FOG LOOP SHOWS VERY FEW ST/FG PATCHES DEVELOPING...MOST OFF
BAJA COAST THROUGH 0745Z...IN ECLIPSE SINCE. PGRADS ARE ONSHORE TO
THE DESERTS BUT TRENDING WEAKLY OFFSHORE TO THE NORTHEAST. 00Z NKX
RAOB HAS VERY WEAK EASTERLY FLOW BELOW 500 MB WITH INCREASING
SOUTHERLY FLOW ABOVE TO 30 KTS AT 300 MB. PW IS ONLY ABOUT 1 INCH
WITH A K INDEX OF 22. MARINE INVERSION BASED NR 1.5K FT.  

00Z MODELS IN AFOS BUT NO NTRANS. SW US HIGH REMAINS INTACT THROUGH
48 HOURS AS CUT-OFF LOW SLIPS SOUTH OFF THE WEST COAST TO NR 40N 
130W. INCREASING SOUTH TO SOUTHEAST FLOW ALOFT WILL PRIME THE
ATMOSPHERE FOR MTN/DSRT TS ACTIVITY THROUGH TUESDAY. MOISTURE PLUME
EVIDENT ON SATELLITE NR 120W NOT EXPECTED TO AFFECT OUR CWA BUT WILL
NEED TO WATCH. WILL TONE DOWN ST/FOG IN FCST PKG.

EXTENDED PROGS SHOW THE SW US HIGH BEGINNING TO WEAKEN TOWARD THE END
OF THE WEEK AS THE CUT-OFF LOW OPENS UP AND MOVES INLAND. DEEP
ALEUTIAN LOW IS REPLACED BY STRONG RIDGING ALONG 160W. THIS IN TURN
EXPANDS TROUGHING ACROSS THE EAST PACIFIC. THESE DEVELOPMENTS SHOULD
SIGNAL AN END TO THE VERY WARM CONDITIONS AS OUR UPPER FLOW BECOMES
MORE SOUTHWESTERLY AND HEIGHTS AND THICKNESS BEGIN TO FALL.

SAN UU 082/070 080/070 078 10----

JAD