Forecast Discussions mentioning "ACARS", "MDCRS", or "AIRCRAFT" received at FSL on 01/10/02

MORE CLOUDINESS THAN PERHAPS WAS EXPECTED ACROSS THE FORECAST AREA THIS EVENING. RATHER WELL ESTABLISHED MARINE LAYER IS IN PLACE ACROSS L.A. COUNTY...WITH ACARS SHOWING THE INVERSION BASE NEAR 3000 FEET. APPEARS THAT A CATALINA EDDY IS SPINNING AS WELL. FURTHER NORTH... SPILLOVER LOW CLOUDS FROM THE SAN JOAQUIN VALLEY ARE AFFECTING MUCH OF SLO AND NORTHERN PORTIONS OF SBA COUNTY. OFFSHORE FLOW HAS BECOME ESTABLISHED ACROSS SRN SBA COUNTY THIS EVENING...WITH MONTECITO HILLS REPORTING NORTH WINDS GUSTING TO 38 MPH AT 8 PM. BELIEVE THAT THE OFFSHORE FLOW WILL KEEP LOW CLOUDS OUT OF SRN SBA AND VTU COUNTIES OVERNIGHT FOR THE MOST PART...BUT MARINE LAYER ACROSS L.A. COUNTY IS QUITE WELL ENTRENCHED...AND WILL BE DIFFICULT TO REMOVE TOO QUICKLY... ESPECIALLY WITH AN EDDY IN PLACE. WILL UPDATE THE ZONES TO INCREASE LOW CLOUD COVERAGE ACROSS THE L.A. COAST AND VALLEYS FOR THE REMAINDER OF TONIGHT...WITH CLOUDS CONTINUING INTO THE MORNING HOURS ACROSS THE COAST. THE OFFSHORE FLOW SHOULD KICK IN AROUND SUNRISE ACROSS THE VALLEYS AND CLEAR THINGS OUT. FURTHER NORTH...CLOUDS SHOULD DECREASE OVERNIGHT ACROSS THE CENTRAL COAST...BUT LOW LEVEL MOISTURE WILL REMAIN TRAPPED WITH CONSIDERABLE CLOUDINESS ALL NIGHT AND INTO THE MORNING ACROSS THE INTERIOR OF SLO/SBA COUNTIES.

FORECAST PROBLEM FOR THURSDAY WILL BE THE BATTLE BETWEEN THE MARINE LAYER AND THE OFFSHORE FLOW ACROSS SE PARTS OF THE FCST AREA... MAINLY L.A. COUNTY. OFTEN IN THESE SITUATIONS THE MARINE LAYER WINS OUT...ESPECIALLY WHEN THE OFFSHORE FLOW IS MARGINAL AS IT IS EXPECTED TO BE THRU MUCH OF THURS. THIS COULD KEEP MAX TEMPS BELOW PREVIOUSLY FORECAST VALUES...AND KEEP THE CANYON WINDS ABOVE THE SURFACE SKIPPING ALONG THE TOP OF THE MARINE LAYER WILL LEAVE ANY POSSIBLE ADJUSTMENTS TO THURSDAY FOR THE MID SHIFT HOWEVER.

BY THURSDAY NIGHT AND FRIDAY...MARINE LAYER WILL HOPEFULLY BE SWEPT OUT TO SEA COMPLETELY...WHICH SHOULD ALLOW SOME CANYON WINDS TO DEVELOP...ALONG WITH WARM TEMPS IN THE LOWER ELEVATIONS FOR FRI. WINDS COULD REACH MARGINAL ADVISORY LEVELS FRI MORNING...ALTHOUGH EVEN THE GENERALLY BULLISH MESO-ETA IS NOT QUITE AS AGGRESSIVE AS PREVIOUS RUNS WITH THE OFFSHORE GRADIENTS AND UPPER SUPPORT.

NICE WEATHER WILL CONTINUE THROUGH THE WEEKEND...WITH MOSTLY CLEAR SKIES AND MILD TEMPS. WEAKENING OFFSHORE FLOW WILL ALLOW FOR SOME SLIGHT COOLING ON SUNDAY...BUT THIS SHOULD ONLY AMOUNT TO A FEW DEGREES. MODELS DIVERGE EARLY NEXT WEEK...WITH A VARIETY OF SOLUTIONS FROM CONTINUED WEAK RIDGING (UKMET)...TO AN INSIDE SLIDER (MRF)...AND A DEEP CUTOFF LOW DEVELOPING OVER NRN CA (ECMWF). AT THIS TIME HAVE OPTED FOR THE COMPROMISE MRF...WITH P/C SKIES AND COOLER TEMPS MON AND TUE...FOLLOWED BY CLEAR AND WARMER CONDITIONS WED AS OFFSHORE FLOW DEVELOPS ONCE AGAIN. CONSIDERABLE UNCERTAINTY REGARDING THE DETAILS... BUT THE MODEL CONSENSUS HAS DEFINITELY TRENDED AWAY FROM THE COLD AND WET PATTERN ADVERTISED YESTERDAY...TOWARD A DRY AND PERHAPS BREEZY REGIME INSTEAD. JANUARY HAS BEEN QUITE DRY THUS FAR...WITH ONLY 0.12 INCHES OF RAINFALL RECORDED AT DOWNTOWN LOS ANGELES. IF THE MEDIUM RANGE MODELS ARE CORRECT...THERE IS NO RAIN IN SIGHT THRU THE NEXT SEVERAL DAYS. TIME WILL TELL...IT IS JANUARY AFTER ALL.

LAX 0000. JACOBSON

.LOX...SMALL CRAFT ADVISORY (SEE LAXCWFLAX). HEAVY SURF ADVISORY (SEE LAXMWSLAX).



.SYNOPSIS...THE MARINE LAYER WILL CAUSE AREAS OF LOW CLOUDS AND FOG WEST OF THE MOUNTAINS TONIGHT AS UPPER LEVEL LOW PRESSURE MOVES EAST. OFFSHORE FLOW WILL DEVELOP THURSDAY AND CONTINUE INTO FRIDAY FOR LOCAL STRONG GUSTY WINDS THROUGH AND BELOW MOUNTAIN CANYONS AND PASSES. OTHERWISE...FAIR SKIES WILL OCCUR WITH WARMER DAYS WEST OF THE MOUNTAINS INTO THE WEEKEND. LOW PRESSURE ALOFT WILL BRING COOLING WITH MORE CLOUDS EARLY NEXT WEEK.

.DISCUSSION...LOW CLOUDS WERE FORMING AND DISSIPATING IN A HAPHAZARD WAY WEST OF THE MOUNTAINS...WHICH IS TYPICAL WHEN A MODERATE-DEPTH MARINE LAYER WEAKENS. THE 3200-FOOT DEEP MARINE LAYER AT 00Z AT NKX WAS A BIT LESS WELL-DEFINED AT ACARS SITES THIS EVENING WITH ONT SHOWING TWO WEAK INVERSIONS IN THE LOW LAYERS. EXPECT AREAS OF LOW CLOUDS AND FOG OVERNIGHT AS THE INVERSION SINKS LOWER...AND THE LOW CLOUDS MAY BE ABLE TO CLEAR THE INLAND EMPIRE BY SUNRISE AS THE OFFSHORE FLOW KICKS IN.

THE WIND ADVISORY LOOKS GOOD FOR NOW FOR THU INTO FRI...THOUGH THE WINDS COULD GO HIGHER. WHILE COLD AIR ADVECTION IS GOOD...FEEDING HIGH VALUES INTO THE LOCAL WIND PROGRAM...THERE ARE NO WINDS OF 50 KTS OR HIGHER AT OR BELOW 500 MB...SO THE EXTREME HIGH WINDS WILL BE TOUGH TO GET. GENERALLY...00Z MSO/NGM/AVN HAVE WINDS AROUND 30 KNOTS AT 850 MB...AND 18Z WORKSTATION ETA HAS WINDS UP TO 40 KNOTS THU EVENING BELOW THE CAJON PASS AT 850 MB ALONG WITH LARGE DOWNWARD OMEGA VALUES...AND 35 KNOTS THU AM. SO...30-40 MPH WITH STRONGER GUSTS LOOKS GOOD FOR NOW FOR THE INLAND EMPIRE.

A QUICK UPDATE WILL BE ISSUED TO THE ZONES...MAINLY TO CHANGE THE LOW CLOUDS AND FOG WORDING. .SAN...WIND ADVISORIES...SEE LAXNPWSAN. HEAVY SURF ADVISORY...SEE LAXMWSSAN.

MAXWELL



NO BIG DIFFERENCES NOTED THIS RUN. STILL LOOKING AT QUICK UPPER FLOW THROUGH THE DAY TODAY AS SURFACE LOW OVER SE CANADA TRACKS TO CANADIAN MARITIMES. LOOKS DRY WITH JUST SOME CIRRUS FOR TODAY. OVERNIGHT LOCAL ACARS SOUNDINGS SHOW ALL THE WARM AIR JUST OFF THE DECK. GUIDANCE NUMBERS STILL SHOWING HIGHS NEAR 50 TODAY AND WON'T ARGUE.

BY TONIGHT...WEAK SURFACE FRONT MOVES THROUGH AND EXPECT LITTLE MORE THAN CIRRUS. FWC'S A FEW DEGREES COLDER THAN MAV'S AND WILL SPLIT THE DIFFERENCE.

ON FRIDAY...WEAK LOW PRESSURE MOVES ALONG FRONT WELL TO OUR SOUTH AND MOST OF THE MOISTURE GOES WITH IT. THIS LOW IS PROGRESSIVE ...AND TIMING LOOKS TO BE DURING THE MORNING HOURS. ANY ASSOCIATED MID LEVEL LIFT MOVES WELL TO OUR SOUTH BUT WITH SOME MOISTURE AVAILABLE AND UPPER TROUGH SWINGING THROUGH EARLY FRIDAY...WILL INCLUDE A MINIMAL 30 POP ACROSS THE REGION AND WILL TRY TO EMPHASIZE MORNING HOURS AS BEST CHANCE. IF ANYTHING DOES FALL...IT WILL BE IN THE FORM OF RAIN AS THICKNESS PROFILES AND SOUNDINGS SUGGEST. BY AFTERNOON...RIDGE ALREADY POKING IN AND DOWNSLOPE NORTHWEST FLOW KICKS IN. WILL CUT OFF PRECIP BY EARLY AFTERNOON IN MATRICES. GUIDANCE TEMP NUMBERS CLOSE.

DRY FRIDAY NIGHT AND SATURDAY. THEN NEXT SHORTWAVE QUICKLY MOVES OUT OF CANADA AND TAKES SURFACE LOW ACROSS GRTLKS SATURDAY NIGHT AND EARLY SUNDAY. THIS IS A BIT FASTER THAN LAST NIGHT'S SOLUTION AND WILL MENTION SNOW SHOWERS FOR THIS TIME FRAME.

IN FAST FLOW...RIDGE LATE SUNDAY AND MONDAY IS REPLACED BY NEXT SHORTWAVE TROUGH FOR TUESDAY.

MARINE...SMALL CRAFT SEA CONDITIONS CONTINUE ACROSS THE CSTL WATERS SOUTH OF LI. WAVE WATCH III INDICATES THAT SEAS WILL SUBSIDE AS THE DAY PROGRESSES. THE GRADIENT WILL RELAX AS WELL. WINDS SHOULD REMAIN BELOW SCA CRITERIA UNTIL LATE IN THE FRIDAY AS THE FRONT PUSHES EAST AND THE RIDGE BUILDS.

.OKX... CT...NONE. NJ...NONE. NY...NONE. MARINE...SMALL CRAFT ADVISORY FOR CSTL WATERS. ANZ350-353-355.

$$ PW



N-S GRADS HAVE INCRSD DURG THE PAST 24 HRS...AND W-E GRADS HAVE TRENDED STRONGLY OFSHR. N TO NE WINDS HAVE INCRSD SIGNIFICANTLY ACRS THE MTNS OF L.A./VTU COUNTIES...AND WL LIKELY REACH ADVISORY LVLS THIS A.M.. WL ISSUE WIND ADVISORIES FOR THOSE ZONES. EDDY CRCLN AND MARINE INVERSION WAS KEEPING SOME CLDS AND HAZE ACRS L.A. CNTY. HWVR...ACARS SOUNDINGS SHOW THAT THE INVERSION WAS WKNG...AND SATELLITE IMAGERY SHOWED THE EDDY CRCLN DRIFTING TO THE S AND BREAKING APART. AS A RESULT...CLDS HAVE DECRSD STEADILY ACRS L.A. CNTY...SO XPCT SKIES TO BE MOSTLY CLR BY DAYBREAK. XCPTN WL BE N AND NE FACING MTN SLOPES OF SLO...SBA...VTU AND L.A. COUNTIES...WHERE UPSLOPE FLOW WAS CAUSING SOME LOW CLDS AND DENSE FOG...WHICH SHOULD PERSIST THRU EARLY THIS MORNING. SOME OF THESE CLDS WERE ALSO SPILLING INTO THE INTERIOR VLYS OF SLO/SBA COUNTIES...SO WL START THOSE AREAS OFF WITH PTLY CLDY SKIES.

AS THE MARINE INVERSION CONTS TO WKN...WNDS SHOULD SPRD INTO THE VLYS OF L.A./VTU COUNTIES...AND LCLLY INTO CSTL SXNS BELOW PASSES AND CYNS. HWVR...WITH A STRONG MARINE INFLUENCE EXTENDING WELL INTO THE VLYS...IT MAY BE A STRUGGLE FOR WINDS TO BECOME WDSPRD UNTIL LATER THIS MORNING...NEAR THE END OF THE DIURNALLY FAVORED TIME PERIOD FOR STRONG WNDS. THEREFORE...ALTHOUGH UPR LVL SUPPORT ACRS THE AREA IS DECENT... HAVE DECIDED TO KEEP ADVISORIES LIMITED TO THE MTNS. IF THE MARINE AIR SCOURS OUT QUICKLY ENOUGH THIS MORNING...HWVR...ADVISORIES MAY HAVE TO BE EXTNEDED INTO THE VLYS. WITH SIGNIFICANT INCREASES IN THICKNESS VALUES ACRS THE AREA AS THE UPR TROUGH PULLS INTO AZ...INCRG OFSHR FLOW...AND WARMING AT H85/H95...XPCT QUITE A BIT OF WARMING ACRS THE FCST AREA W OF THE MTNS TODAY.

UPR RDG WL BUILD STRONGLY INTO CA TONIGHT AND FRI. OFSHR GRADS WL ACTUALLY CONT TO INCRS AT THE SFC TONIGHT AND EARLY FRI. DESPITE WKNG UPR LVL FLOW...STRONG SUBSIDENCE...IMPRESSIVE PRES GRADS AND MDT THERMAL GRADS MAY ALLOW WINDS TO REACH ADVISORY LVLS LATE TONIGHT AND FRI MORNING ACRS THE VLYS OF L.A. AND VTU COUNTIES...AND POSSIBLY EVEN ACRS CSTL SXNS OF VTU CNTY. ADDITIONAL INCREASES IN THICKNESSES AND BOUNDARY LAYER TEMPS SHOULD HELP PRODUCE SEVERAL MORE DEGS OF WARMING ACRS THE AREA ON FRI.

WK S/WV TROUGH MOVING INTO NRN CA FRI NIGHT AND SAT WL BEGIN TO FLATTEN THE UPR RIDGE ACRS THE STATE...AND POSSIBLY ALLOW SOME HIGH CLDS TO PUSH ACRS THE FCST AREA. RETURN TO WK ONSHR FLOW SAT AFTERNOON SHOULD PRODUCE SOME COOLING ACRS THE CSTL PLAIN...BUT XPCT THE VLYS TO REMAIN WARM. AS THE S/WV PUSHES ACRS INTO THE DESERT SW SAT NIGHT/SUN... THICKNESSES WL BEGIN TO FALL ACRS THE FCST AREA...AND A FEW DEGS OF COOLING IS XPCTD IN MOST AREAS ON SUN. MRF HAS BACKED OFF ON THE SHARPNESS OF THE TROUGH DVLP ACRS CA MON AND TUE...AND NOW SHOWS BROAD CYCLONIC NWLY FLOW ACRS THE AREA MON THRU WED WITH A FEW VORTS PUSHING ACRS THE AREA. UKMET IS IN DECENT AGREEMENT WITH THIS SOLN... BUT ECMWF CONTS TO SHOW MORE OF A SIGNIFICANT TROUGH. HAVE DECIDED TO BUY OFF ON THE TREND TOWARD A DRY SOLN...WHICH WOULD MEAN LITTLE THREAT OF RAIN ACRS THE FCST AREA THROUGH NEXT WEEK.

LAX 000. BRUNO.

.LOX...SMALL CRAFT ADVISORY (SEE LAXCWFLAX). HEAVY SURF ADVISORY (SEE LAXMWSLAX). WIND ADVISORY (SEE LAXNPWLAX),