Forecast Discussions mentioning "ACARS", "MDCRS", or "AIRCRAFT" received at FSL on 02/21/02

SKIES MOSTLY CLEAR OVER MUCH OF THE DISTRICT THIS EVENING. SOME LOW CLOUDS PERSISTING OVER SANTA MONICA BAY INTO THE IMMEDIATE COAST FROM MALIBU TO JUST S OF LAX. SOME CLOUDS OVER THE SOUTHERN SAN JOAQUIN VALLEY WERE DRIFTING WEST INTO SLO COUNTY THIS EVENING AS WELL. AN IMPRESSIVE EAST FLOW OVER SLO COUNTY THIS EVENING WITH BRANCH MOUNTAIN REPORTING EAST WINDS 22 GUSTING TO 33 MPH AT 9 PM. GOOD OFFSHORE GRADIENTS ALONG S SBA COAST THIS EVENING...BUT THUS FAR NO REPORTED GUSTY CANYON WINDS. LOCAL GUSTY WINDS WILL BE POSSIBLE THERE THRU ABOUT MIDNIGHT THEN DIE OFF AS LOW LEVEL WINDS SHIFT TO AN EASTERLY DIRECTION ACCORDING TO MESO-ETA CROSS SECTIONS. THE MARINE LAYER WAS GRADUALLY SHRINKING THIS EVENING...WITH THE LATEST ACARS SOUNDINGS FROM LAX AND LGB SHOWING A SURFACE BASED INVERSION...AND A VERY WEAK INVERSION FROM ABOUT 1700 FEET TO 2400 FEET. LOW LEVELS STILL RATHER MOIST BUT THE MESO-ETA SHOWS A DRYING TREND THRU THU MORNING AS SUBSIDENCE AND OFFSHORE FLOW INCREASES.

UPPER RIDGE BUILDS INTO THE DISTRICT THRU FRI THEN WEAKENS FRI NITE AND SAT AS AN UPPER TROF MOVES OVER THE TOP OF THE RIDGE INTO NORTHERN CALIFORNIA AND THE GREAT BASIN. DOES NOT APPEAR THERE WILL BE MUCH SUPPORT FOR STRONG OFFSHORE WINDS WITH THIS EVENT...BUT LOCALIZED GUSTY CANYON WINDS ARE EXPECTED. BIG QUESTION THIS EVENING IS HOW WARM (HOT?) THE DISTRICT WILL GET ON THURSDAY. THE MESO-ETA IS THE WARMEST OF THE EVENING MODEL SOLUTIONS...WITH 950 MB TEMPS INCREASING 5 TO 9 DEG C FROM TODAY. THE MESO ETA SURFACE TEMPS AT LAX AND CQT REBOUND A WHOPPING 15 DEG C FOR THU FROM TODAY. THICKNESSES AROUND 569 DM AND OFFSHORE GRADIENTS LAX-DAG AT 15Z AROUND -4.5 MB CORRESPONDS TO A DOWNTOWN L.A. (OLD SITE) TEMP WELL INTO THE 80S. AM INCLINED TO BOOST HI TEMPS FARTHER FOR THU OVER PORTIONS OF THE DISTRICT...ESPECIALLY AFTER THE SOMEWHAT UNEXPECTED WARM TEMPS WE HAD TODAY IN SOME AREAS. TEMPS VERY WARM AGAIN FRI...WITH HI TEMPS ALONG THE COASTAL PLAIN BEING REACHED PROBABLY BEFORE NOON...BEFORE THE ONSET OF THE SEABREEZE. SOME OF THE WARMEST VALLEY LOCATIONS COULD APPROACH 90 DEGREES...PERHAPS BOTH DAYS...BUT THE BETTER CHANCE FRIDAY. WOULD NOT RULE OUT NEAR RECORD HI TEMPS BOTH THU AND FRI...WITH SEVERAL RECORD HI TEMPS NOT OUT OF THE QUESTION.

THE LATEST AVN WAS SHOWING ANOTHER UPPER LEVEL RIDGE BUILDING ALONG OR OFF THE W COAST SUN AND MON. TEMPS FORECAST TO COOL DOWN SEVERAL DEGREES SAT...THEN REMAIN RATHER MILD ESPECIALLY INLAND SUN AND MON WITH THE DRY WEATHER CONTINUING.

WILL UPDATE ZONES BY 1015 TO RAISE TEMPS MANY AREAS FOR THU...AND ADJUST SOME OF THE CLOUDINESS WORDING A FEW ZONES FOR TONIGHT. OTHERWISE...BALANCE OF THE ZONES LOOKS GOOD.

LAX 0000. SIRARD

.LOX...SMALL CRAFT ADVISORY (SEE LAXCWFLAX).



.SYNOPSIS...BUILDING HIGH PRESSURE ALOFT AND DEVELOPING OFFSHORE FLOW WILL BRING A WARMING TREND WITH GUSTY WINDS THROUGH AND BELOW CANYONS AND PASSES THURSDAY THROUGH FRIDAY. UPPER LEVEL LOW PRESSURE WILL MOVE PAST TO THE NORTH SATURDAY BRINGING SOME CLOUDS AND COOLING. HIGH PRESSURE AND OFFSHORE FLOW WILL DEVELOP AGAIN EARLY NEXT WEEK AND THEN GRADUALLY WEAKEN.

.DISCUSSION...LOW CLOUDS COVERED MOST OF THE SAN DIEGO COUNTY BEACHES EARLY THIS EVENING BUT HAVE SINCE RETREATED BACK TO SEA. HOWEVER...SOME ADDITIONAL LOW CLOUDS AND FOG WERE FORMING JUST INLAND FROM THE COAST BEFORE 9 PM...INCLUDING AT BROWN FIELD WHERE THE VIS HAD DROPPED TO 1/4 MILE. AN ACARS SOUNDING FROM EARLIER THIS EVENING SHOWED AN 800-FOOT INVERSION AT SAN...SO GIVEN THE OFFSHORE TRENDS...THIS INVERSION WILL CONTINUE TO LOWER...AND MORE DENSE FOG WILL DEVELOP. MOST LIKELY...AS THE NIGHT PROGRESSES...THE DENSE FOG WILL MOVE FROM THE MESAS TO THE IMMEDIATE COAST AND EVENTUALLY OFFSHORE BY SUNRISE.

THE OTHER ISSUE WILL BE THE WIND. 00Z MODELS INDICATE THAT WIND ADVISORIES MAY ULTIMATELY BE NEEDED BELOW THE CAJON PASS AND SANTA ANA MOUNTAINS AND POSSIBLY THE FOOTHILLS OF SAN DIEGO COUNTY...THOUGH THIS WILL BE SOMEWHAT MARGINAL. THE NEAR-SURFACE SUPPORT FOR CANYON/PASS WINDS IS STRONG...BUT SUPPORT IS WEAK AT AND ABOVE 700 MB. THUS...THIS WILL MOSTLY BE A GRADIENT TYPE WIND EVENT WITH FAIRLY WIDESPREAD BREEZY CONDITIONS BUT WITHOUT MUCH OF THE MORE EXTREME BUT MORE FOCUSED MOUNTAIN-WAVE GENERATED WINDS. REGARDLESS...THE OFFSHORE FLOW SHOULD MOSTLY MAKE IT TO THE IMMEDIATE COAST AND ALLOW ALL AREAS WEST OF THE MTNS TO SEE SIGNIFICANT TEMP INCREASES. WITH 850 MB TEMPS OF 14-15 DEG C TRANSLATED DOWNWARD DRY ADIABATICALLY...THAT MEANS SOME AREAS COULD SEE TEMPS INTO THE MID 80S THU...AND EVEN A FEW DEGREES HIGHER FRI WHEN THE COLD AIR ADVECTION STOPS. A FAST MOVING SHORT-WAVE WILL MOVE BY TO THE NORTH OVER THE WEEKEND TO SWITCH OUR SURFACE WINDS BACK ONSHORE FOR COOLER WEATHER AND A RETURN OF AT LEAST AREAS OF LOW CLOUDS. PRECIP SHOULD STAY WELL TO THE NORTH THOUGH. HIGH PRESSURE WILL REBUILD EARLY NEXT WEEK FOR WARMING.

A ZONE UPDATE WILL BE ISSUED SHORTLY.

.SAN...NONE.

MAXWELL



PRES GRADS WERE TRENDING STRONGLY OFSHR EARLY THIS MORNING...WITH N-S AND W-E GRADS NOW MDTLY OFSHR. GUSTY WINDS WERE FAIRLY WDSPRD ACRS THE MTNS...AND ACARS SOUNDINGS AND RAWS DATA SHOW THAT MDT-STG NELY WINDS WERRE OCCURRING ABOVE 2000 FEET...NEAR THE TOP OF A RATHER STRONG INVERSION. LOW CLDS WERE HANGING TOUGH FROM CSTL SXNS IOF SRN SBA COUNTY THRU L.A. COUNTY...AND WITH THE BASE OF THE INVERSION NEAR THE SURFACE...LCLLY DENSE FOG WAS OCCURRING NEAR THE COAST.

INCRSG SUBSIDENCE ACRS THE AREA SHOULD HELP TO FORCE WNDS INTO LOWER LVLS OF THE ATMOS...AND WITH INCRGLY OFSHR GRADS.. MARINE LYR SHOULD BE WIPED OUT THIS A.M.. EXACTLY HOW QUICKLY THIS OCCURS WL BE CRITICAL IN DETERMINING WHAT AREAS RECEIVE GUSTY WNDS TODAY...AND IN DETERMINING MAX TEMPS. XPCT WNDS TO HAVE NO PROBLEM SPRDG INTO THE VLYS BELOW PASSES AND CANYONS THIS A.M.. LACK OF REALLY STRONG SUBSIDENCE COULD MAKE THE EROSION OF THE MARINE INFLUENCE S OF PT CONCEPTION A SLOW PROCESS TODAY...WHICH WOULD MINIMIZE THE THREAT OF STRONG WNDS REACHING THE COAST. HWVR...WITH STRONG OFSHR GRADS AND FAVORABLE WIND DIRECTION...BLV STRONG WNDS WL SPRD ACRS THE VTU CNTY CSTL PLAIN TODAY. WITH 850 MB WNDS AND SUBSIDENCE ONLY AT MODERATE LVLS THIS A.M...BLV WNDS WL STAY JUST BELOW ADVISORY CRITERIA TODAY. HWVR...GIVEN THE STRENGTH OF THE GRADS...THAT WL HAVE TO BE WATCHED CLOSELY. SIGNIFICANT RISES IN THICKNESSES AND BOUNDARY LAYER TEMPS SHOULD LEAD TO A MUCH WARMER DAY ACRS THE FCST AREA. A BIT OF LOW LVL COLD ADVECTION MAY KEEP THE ELEVATED INLAND VLYS SUCH AS THE SANTA CLARITA VLY FROM WARMING AS SIGNIFICANTLY AS THE LOWER VLYS. TEMPS ON THE CSTL PLAIN WL BE TRICKY...DETERMINED BY EFFICIENCY WITH WHICH THE OFSHR GRADS ERADICATE THE MARINE LAYER. STILL LOOKS LIKE MOST OF THE CSTL PLAIN WILL WARM QUITE A BIT TODAY. WITH THE LACK OF A STRONG MARINE PRESENCE AND LIGHT ELY FLOW CONTG MOST OF THE DAY...THE CENTRAL COULD SHOULD REALLY HEAT UP TODAY...WITH TEMPS POSSIBLY REACHING RECORD LVLS IN SOME AREAS.

GRADS WL REMAIN MDTLY OFSHR THRU FRI WITH LCLLY GUSTY WINDS IN THE MTNS AND BELOW PASSES AND CANYONS ON THE CSTL PLAIN THRU FRI MORNING. AGAIN...XPCT WINDS TO STAY BELOW ADVISORY LVLS ACRS THE FCST AREA. WITH BOUNDARY LAYER TEMPS PROGGED TO INCREASE A BIT FRI A.M....AND WITH LESSENING LOW LVL COLD ADVECTION...TEMPS SHOULD WARM IN MOST AREAS ON FRI...WITH A FEW OF THE WARMER VLY LOCATIONS POSSIBLY APCHG THE 90 DEGREE MARK ON FRI. THE XCPTN TO THE WARMING ON FRIDAY WL BE ALONG THE CENTRAL CST...WHERE A RETURN TO ONSHR FLOW WL CAUSE SEVERAL DEGS OF COOLING.

06Z ETA IS FASTER WITH A S/WV TROUGH ACPHG THE PAC NW FRI... PUSHING INTO THE WRN STATES FRI NIGHT AND EARLY SAT...AND IS NOW IN FAIRLY GOOD AGREEMENT WITH THE AVN. THE TROUGH WL WKN QUICKLY AS IT PUSHES INTO THE MEAN RIDGE...BUT IT WL ALSO FLATTEN THE RIDGE ACRS THE AREA. WITH A RETURN TO ONSHR GRADS ON SAT...WITH LOWERING THICKNESSES AND COOLING IN THE BOUNDARY LAYER AND AT 850 MB...XPCT SEVERAL DEGS OF COOLING ACRS THE FCST AREA ON SAT. EVEN STILL...TEMPS SHOULD BE ABOVE NORMAL LVLS IN MOST AREAS. THE UPR RIDGE WL BUILD BACK INTO THE FCST AREA SUNDAY AND MONDAY...AND WITH WK TO MDT OFSHR FLOW AGAIN...TEMPS WILL LIKELY WARM A FEW DEGS IN MOST AREAS FOR SUNDAY AND MONDAY. ANOTHER S/WV DROPPING THRU THE PAC NW INTO THE GREAT BASIN SHOULD CAUSE SOME COOLING TUE AND ESPECIALLY WED.

LAX 000. BRUNO.

.LOX...NONE.