SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDLOX 850 PM PDT SUN SEP 5 1999
SATELLITE IMAGERY SHOWS THE OVERWATER AREAS MOSTLY COVERED WITH LOW
CLOUDS...XCPT FOR A FEW GAPS IN THE LEE OF SOME OF THE ISLANDS. N OF PT
CONCPTN...CLOUDS ARE STARTING TO MOVE ONSHORE IN THE USUSAL LOW LYING
PLACES NR KVBG AND KLPC AND BETWEEN KSBP AND KSMX. S OF PT CONCPTN...
LOW CLOUDS NEVER REALLY LEFT THE SHORELINE IN SOME AREAS ALL DAY AND
HAVE COVERED THE OXNARD AND MOST OF THE LA PLAINS AND ARE CONTINUING TO
SPREAD INLAND ATTM. SOUNDERS AT GOLETA AND USC PEG THE TOP OF THE
MARINE LYR AT ABOUT 2000 FT. THIS IS IN AGREEMENT W SOME PIREPS. HWVR
...AN ACARS SOUNDING INTO ONTARIO AT 0020Z SUGGESTS THE TOPS OF THE
MARINE LYR NR 4000 MSL. LAX-XXX PRESSURE GRADIENTS HAVE TRENDED MOSTLY
ONSHORE FOR THE LAST 12 TO 18 HRS. ATTM...LAX-SFO +1.5...-BFL +3.7...
-DAG +4.7 AND -TRM +6.5. ALONG WITH THE ACARS REPORT...LOOKS LIKE A
SURE THING FOR CLOUDS IN THE VLYS TNITE...PERHAPS REACHING THE LOWER
COASTAL SLOPES TMRW AM.
MTS/DESERTS/INLAND VLYS ALL WARMED TDY VS SAT WITH THE GREATEST RISE
AT CRESTON +8...PASO ROBLES +7...AND SANTA YNEZ +6. HWVR...IT WAS
COOLER ALG THE CST WITH THE GREATEST COOLING AT PISMO BCH AND VENTURA
WITH -5 AND SANTA BARBARA AT -3.
WX PATTERN IS DOMINATED BY AN UPPER LOW CURRENTLY LOCATED ABOUT 400 NM
SW OF PT CONCPTN THAT APPEARS TO BE DRIFTING SLOWLY TO THE SW...AND
ANOTHER TROF MVG THRU WA AND OR TO THE N OF CA. TROF TO THE NORTH SHUD
NOT INFLUENCE OUR LCL WX AND THE LOW TO THE SW WILL JUST HELP TO
MAINTAIN A THICK MARINE LYR. THEREFORE...XPCT LITTLE CHG IN TEMPS MON
AND TUE AS THE 850 TEMPS AND SFC-1000 MB THKNS VARY ONLY +/- A
DEGREE/METER RESPECTIVELY.
XTNDD...XPCT UPR LO TO MV ONSHORE ON WED AND OUT OF THE AREA ON THU AS
HIGH PRESSURE BUILDS OVR AZ/NM AND RIDGES SW THRU BAJA BY THE END OF
THE WEEK. THIS WILL LEAVE THE AREA UNDER SW FLO THRU THE WEEK...KEEPING
THE THREAT OF MONSOONAL MOISTURE AND STORMS OUT OF SRN CA. PATTERN WILL
BE A FEW DEGREES BLO NORMAL AT THE CSTS AND CSTL SLOPES DUE TO
PERSISTANT MRN LYR...BUT WILL WARM UP TO ABV NRML TEMPS IN THE DESERTS
AND MTS BY THE END OF THE WEEK.
LAX 0000. DANIELSON
.LAX...NONE.
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
AFDLOX 930 AM PDT SUN SEP 5 1999
SATELLITE IMAGERY INDICATING FAIRLY EXTENSIVE STRATUS ACROSS COASTAL
AND VALLEY AREAS THIS MORNING. ACARS SOUNDINGS AND USC PROFILER
SHOWING MARINE LAYER DEPTH AROUND 2000 FEET ACROSS THE LA BASIN.
SUBSTANTIAL WARMING TAKING PLACE ABOVE 3000 FEET...AS COMPARED TO 24
HOURS AGO...WHICH HAS STRENGTHENED INVERSION SIGNIFICANTLY.
THIS STRONG INVERSION COMBINED WITH WEAK SURFACE GRADIENTS IS
EXPECTED TO YIELD HAZY CONDITIONS ACROSS COASTAL/VALLEY AREAS
TODAY...WITH SOME LOW CLOUDS LINGERING NEAR THE IMMEDIATE COAST
OF LA/VTU COUNTIES.
WATER VAPOR IMAGERY INDICATING WEAK UPPER LEVEL CIRCULATION OFF
SOUTHERN CALIFORNIA COAST. MODELS HAVE THIS UPPER CIRCULATION
RETROGRADING TO THE SOUTHWEST OVER THE NEXT 48 HOURS...WITH SLIGHTLY
RISING HEIGHTS OVER AREA. APPEARS THAT MODEL DEPICTED LOW LEVEL
CIRCULATION WILL STAY FAR ENOUGH OFF THE COAST TO HAVE LITTLE IMPACT
ON MARINE LAYER. HOWEVER...IF LOW LEVEL CIRCULATION LINGERS CLOSER TO
COAST...COULD HAVE EDDY-LIKE INFLUENCE...WITH DEEPER MARINE LAYER
REMAINING IN PLACE.
WARMING TREND FOR INLAND AREAS STILL LOOKS ON TRACK TODAY. COASTAL
AREAS SHOULD ONLY SEE SLIGHT TEMPERATURE RISES DUE TO MARINE
INFLUENCE. INLAND AREAS COULD THEN SEE A COUPLE MORE DEGREES OF WARMING
ON MONDAY.
LAX 000. GOMBERG.
.LAX...NONE.