Forecast Discussions mentioning ACARS, received at FSL on 05/09/00

ONSHORE GRADIENTS GRADUALLY WEAKENING ACROSS THE DISTRICT THIS EVENING...HOWEVER THE N-S GRADIENTS OVER SBA COUNTY WERE INCREASING. AT 04Z THE SBA-SMX GRADIENT WAS -4.5 MB. VERY STRONG WINDS OVER THE ANTELOPE VALLEY HAVE SUBSIDED BELOW WIND ADVISORY LEVELS SO CANCELLED THAT ADVISORY AT 8 PM. HOWEVER...STRONG WINDS INCREASED ACROSS S SBA COUNTY COAST AND MOUNTAINS SO A WIND ADVISORY WAS ISSUED FOR THAT AREA AT 8 PM IN EFFECT UNTIL 3 AM TUE. ELSEWHERE...LOW CLOUDS AND LOCAL DENSE FOG MOVED INTO THE CENTRAL COAST AND SANTA YNEZ VALLEY THIS EVENING...WITH SOME LOW CLOUDS INTO THE COASTS OF VTU AND L.A. COUNTIES. MARINE LAYER BELOW 1000 FEET OVER CENTRAL COAST...1000 TO 1500 FEET OVER L.A. COUNTY COAST...AND OVER 3000 FEET DEEP OVER THE VALLEYS AS SHOWN ON ACARS. WITH SOME ONSHORE GRADIENTS CONTINUING... LOW CLOUDS SHOULD OVERSPREAD MOST COASTAL AND VALLEY LOCATIONS BY LATE TONIGHT.

FLAT UPPER RIDGE OVER THE DISTRICT THRU TUE...THEN AN UPPER TROF BEGINS TO MOVE DOWN THE W COAST WED. SKIES SHOULD BECOME MOSTLY SUNNY OVER THE DISTRICT BY TUE AFTERNOON. THE MARINE LATYER SHOULD INCREASE SOME TUE NITE WHICH SHOULD ALLOW MORE LOW CLOUDS TO MOVE INLAND. WITH A DEEPER MARINE LAYER WED LOW CLOUDS MAY HAVE A MORE DIFFICULT TIME CLEARING... BUT MOST AREAS SHOULD BECOME MOSTLY SUNNY AGAIN WED AFTERNOON. TEMPS WARMER TUE...THEN COOLER WED AS HEIGHTS/THICKNESSES DROP.

IN THE EXTENDED...A LOT OF UNCERTAINTY WITH THE MEDIUM RANGE MODELS. WENT WITH THE MRF WHICH SHOWS A BROAD UPPER TROF TO LINGER OVER THE WESTERN U.S. THRU THE PERIOD. A SHORTWAVE TROF WILL SWING ON THRU THE AREA FRI MORNING TO BRING A CHANCE OF LIGHT SHOWERS OR DRIZZLE IN A DEEP MARINE LAYER...OTHERWISE DRY BUT COOLER THAN NORMAL WEATHER TO PREVAIL THU THRU SAT...WITH THE COOLEST TEMPS FRI AND SAT. THE TROFFINESS WILL ALSO BRING BREEZY TO WINDY CONDITIONS TO THE DISTRICT MAINLY THU AND FRI.

LAX 0000. SIRARD

.LAX...WIND ADVISORY (SEE LAXNPWLAX) SMALL CRAFT ADVISORY (SEE LAXCWFLAX)



WL HAVE BRIEF AFD THIS AFTN DUE TO DVLPG SVR WX. VSBL SATLT LOOPS PAST CPL HRS SHWG VRY STG LO LVL MOISTURE CONVERGENCE INTO NRN IL. CAPES FROM SOUNDINGS MODIFIED WITH ACARS TEMPS NOW APCHG 4000 J/KG. CONVERGENCE TAKING PLACE ALG OLD BNDRY FM JUST N OF MKE-JVL-WEST OF RFD TO A WAVE CREST JUST NW OF MLI. LN TCU THEN EXTENDS SWWD ACRS NRN MO-ERN KS. TSTMS HAVE BEGUN TO DVLP RPDLY INVOF THE APEX OF THE WAVE FEATURE WITH DENSE ANVIL CANOPY FANNING RPDLY AS WELL. EXPCT TSTMS TO CONT TO FIRE NXT CPL HRS...EVENTUALLY FORMING A SVR SQLN ACRS NWRN IL. ACTIVITY SHUD THEN PROPAGATE ESEWD ACRS ENTR FCST AREA THIS AFTN-EVE.

STMS SHUD EVENTUALLY EVOLVE INTO HVY RAIN AREA LATE THIS EVE. ON TUES...ALL GUID IS CONSISTENT IN BRINGING S/W NEWD ALG STALLED SFC FNT TO S OF FA. SIG UVV FIELD ASSD WITH THIS FEATURE AS S/W BECOMES NEG TILTED WITH TIME ON TUES. WITH DEEP ATMOS MOISTURE STILL IN CLOSE PROXIMITY...AM EXPECTING HVY RNFL EVENT TO SET UP SOMEWHERE ACROSS FA. IF THIS EVOLVES AS FCST...A FLASH FLOOD WATCH MAY BE REQUIRED.

BASICALLY GOING WITH GUID AFT 24HRS AS MDLS IN GENLY CLOSE AGRMT AND FAIRLY CONSISTENT OVR PAST FEW RUNS. MOS TEMPS O.K.

.CHI...NONE.

MERZLOCK



...SYNOPSIS... AREAS OF NIGHT AND MORNING LOW CLOUDS AND FOG WILL CONTINUE WEST OF THE MOUNTAINS FOR MUCH OF THE WEEK WITH GREATEST COVERAGE THE LATTER HALF OF THE WEEK. WEAK HIGH PRESSURE WILL BRING SOME WARMING TO INTERIOR LOCATIONS FOR TUESDAY...FOLLOWED BY A GRADUAL COOLING TREND FOR MOST AREAS WEDNESDAY THROUGH SUNDAY. BREEZY CONDITIONS IN THE MOUNTAINS AND DESERTS WILL DIMINISH TONIGHT...THEN RETURN WEDNESDAY THROUGH SUNDAY.

...DISCUSSION... LATE AFTERNOON AND EARLY EVENING ACARS SOUNDINGS SHOW TWO INVERSIONS OF SIGNFICANCE. ALG THE CST...THE BASE OF THE LWR INVERSION RANGES FM AROUND 1500 FT LAX/LGB/SNA TO 2500 FT SAN WITH CIGS FOR MOST CSTL SITES ASSOCD WITH THIS LWR INVERSION. THERE IS ALSO A SECOND...HIGHER INVERSION...GENERALLY AROUND 5000 TO 6000 FT DEPENDING UPON LOCATION. CLOUDS IN THE INLAND VLYS AND ALG THE CSTL MTN SLOPES ARE ASSOCD WITH THIS SECOND INVERSION. WITH WK TRANSITORY UPR RDGG BUILDING OVR SRN CA TONIGHT INTO EARLY TUE...THE SECOND UPR INVERSION SHOULD LWR WITH A SINGLE LWR INVERSION BY TUE NIGHT. WHETHER THE INVERSION AT 5000 TO 6000 FT GRADUALLY LWRS OVERNIGHT OR SIMPLY REDEVELOPS DURG THE DAY TUE WITH A RESULTING SINGLE LWR STRONGER INVERSION REMAINS TO BE SEEN. THE 12Z COAMPS SHOWED A MARINE LYR DEPTH FOR SRN CSTL SXNS AROUND 2000 FT FOR TUE NIGHT. THIS SEEMS ABOUT RIGHT GIVEN THE SYNOPTIC INFLUENCES. ASIDE FM CHANGES IN THE INVERSION HEIGHT...MDLS SHOW WK CSTL EDDIES TONIGHT AND AGAIN TUE NIGHT INTO WED. MARINE LYR SHOULD REACH MINIMUM DEPTH TUE NIGHT...THEN BEGIN INCRG IN DEPTH THE REST OF THE WEEK...TO WHAT DEGREE IS DEPENDENT UPON THE EXTENDED MDL OF CHOICE. NCEP GENERALLY PREFERRED THE MRF...BUT EXTENDED MDLS REMAIN IN POOR AGREEMENT FOR LATE IN THE WEEK THROUGH THE WEEKEND OVR THE ERN PAC AND WRN NOAM...GENERALLY DUE TO DIFFERENCES IN HANDLING OF UPSTREAM SHORTWAVES OVR THE WRN AND CNTRL PAC. CURRENT EXTENDED FORECAST LOOKS REASONABLE GIVEN ALL OF THE ABV.

IN THE DESERTS...MDT NWLY FLOW PATTERN HAS BROUGHT GUSTY WINDS...JUST BLO ADV LVLS...TO THE APPLE...YUCCA...AND COACHELLA VLYS TODAY INTO THIS EVENING. WINDS SHOULD BE A NOTCH LESS FOR TUE...THEN RETURN TO MON LVLS FOR WED AND THU.

SAN 0000

.SAN...NONE.

MARTIN