Forecast Discussions mentioning ACARS, received at FSL on 03/25/01

...SYNOPSIS... HIGH PRESSURE ALOFT WILL BRING WARMER WEATHER TODAY...ESPECIALLY TO THE INLAND...MOUNTAIN AND DESERT AREAS. A WEAK TROUGH OF LOW PRESSURE WILL BRING GRADUAL COOLING SUNDAY AND MONDAY...WITH GUSTY WINDS IN THE MOUNTAINS AND DESERTS.

...DISCUSSION... 12Z NKX SOUNDING SHOWED THE MARINE LAYER AROUND 2700 FEET...COMPARED TO 3700 FEET 24 HOURS PREVIOUS. ACARS DATA FROM ONTARIO SHOWED THE INVERSION WAS SHALLOWER OVER THE INLAND EMPIRE...AROUND 1800 FEET...AND BREAKS IN THE CLOUDS WERE ALREADY OBSERVED AT 1600Z IN THIS THINNER CLOUD LAYER.

THE INVERSION WAS QUITE STRONG THIS MORNING WITH TEMPERATURES ABOVE THE MARINE LAYER 11 DEGREES WARMER THAN YESTERDAY. THIS MAY DELAY THE BURNOFF OF THE CLOUDS IN SOME AREAS. ALSO...THE VISIBLE SATELLITE IMAGERY SHOWED A SOLID CLOUD DECK OVER COASTAL SAN DIEGO AND ORANGE COUNTIES...EXTENDING BEYOND THE ISLANDS TO ABOUT 100 MILES OFFSHORE. CLOUD BURNOFF AT THE COAST WILL BE SLOWEST TODAY...AND WITH STEEP WEST-EAST TEMP GRADIENTS THIS AFTERNOON...THE CLOUDS MAY HANG IN AT SOME COASTAL SECTIONS. FARTHER INLAND ABOVE THE INVERSION...TEMPERATURES IN THE MOUNTAINS AND DESERTS WERE ALREADY 5 TO 10 DEGREES WARMER THAN AT THIS TIME YESTERDAY.

WEAK UPPER RIDGE OVER THE SOUTHWEST WILL MOVE EAST THIS AFTERNOON...FOLLOWED BY A FAST MOVING SHORTWAVE THAT WILL LOWER HEIGHTS...GRADUALLY DEEPEN THE MARINE LAYER AND INCREASE THE ONSHORE FLOW FOR GRADUAL COOLING SUNDAY AND MONDAY. THIS SHORTWAVE WILL ALSO BRING STRONGER WESTERLY WINDS TO THE MTNS SUNDAY AND MONDAY.

IN THE EXTENDED...NO SIGNIFICANT WEATHER FEATURES WILL IMPACT THE REGION. A WEAK RIDGE BUILDS WEDNESDAY AND THURSDAY...FOLLOWED BY ANOTHER WEAK SHORTWAVE FRIDAY. THIS PATTERN WILL BRING SMALL DAILY CHANGES IN TEMPERATURES AND MARINE LAYER CLOUD COVER...BUT NO RAINFALL. SAN 000

.SAN...NONE.

MOEDE



STRATUS CONTINUES THIS MORNING ACROSS MOST COASTAL AND VALLEY AREAS. LATEST ACARS DATA AND PILOT REPORTS INDICATING MARINE LAYER DEPTH BETWEEN 2000 AND 2500 FEET THIS MORNING...WHICH IS ABOUT 1000 FEET LOWER THAN YESTERDAY. THIS COMBINED WITH WEAKER ONSHORE GRADIENTS SHOULD ALLOW FOR BETTER CLEARING TODAY...ESPECIALLY ACROSS INLAND AREAS. 12Z SOUNDINGS AND PROFILER DATA ALSO INDICATING SIGNIFICANT WARMING BETWEEN 3000 AND 4000 FEET...WHICH WILL RESULT IN WARMING TODAY ACROSS THE MOUNTAINS AND HIGHER VALLEYS.

WEAK UPPER RIDGE OVER AREA TODAY WILL FLATTEN TONIGHT AND SUNDAY AS AN UPPER LEVEL TROUGH MOVES INTO THE PACIFIC NORTHWEST. ONSHORE FLOW WILL INCREASE ON SUNDAY...LEADING TO A DEEPER MARINE LAYER AND COOLER TEMPERATURES. NEW 12Z MESO-ETA SHOWING SURFACE PRESSURE GRADIENTS TRENDING SHARPLY OFFSHORE TO THE NORTH BY LATE SUNDAY NIGHT...CONTINUING INTO MONDAY.

THIS COULD GENERATE WIND ADVISORY THRESHOLD WINDS ACROSS SOUTHERN SBA COUNTY LATE SUNDAY NIGHT INTO MONDAY...AND COULD CAUSE A DECREASING STRATUS TREND ACROSS NORTHERN PORTIONS OF OUR FORECAST AREA. HOWEVER... AS NORTHWEST FLOW INCREASES ACROSS CENTRAL COAST...LOOK FOR GOOD POSSIBILITY OF EDDY FORMATION...WHICH WOULD LIKELY KEEP LA BASIN VULNERABLE TO LOW CLOUDS RIGHT THROUGH MONDAY.

LAX 000. GOMBERG.

.LAX...NONE



HAVE UPDATED ZONE FORECAST FOR LAKE EFFECT OVER NORTHERN PORTER COUNTY INDIANA.

KLOT AND KIWX RADARS INDICATING AREA OF LIGHT SNOW HAS DEVELOPED OVER NORTHERN PORTER COUNTY...WITH REFLECTIVITY MAXES OF GREATER THAN 25 DBZ. NEAREST ASOS...VALPARAISO...NOT REPORTING PRECIP THAT FAR INLANDD...BUT REFLECTIVITY SUGGESTS THAT AT LEAST SOME SNOW PROBABLY REACHING THE GROUND ALONG THE LAKE SHORE.

2130Z ACARS SOUNDING FROM OHARE SHOWS 850 TEMP OF -13...WITH ADIABATIC LAPSE RATE TO THE SURFACE. CURRENT LAKE WATER TEMPS AROUND +2...SO 15 DEGREE SURFACE TO 850 MB DIFFERENCE. WEST/NORTHWEST SURFACE WINDS LIMITING FETCH OVER WATER...ALTHOUGH IT APPEARS SUFFICIENT INSTABILITY AND CONVERGENCE PRESENT ALONG SHORE TO DEVELOP THIS SMALL BAND. SUSPECT THAT SLIGHT BACKING OF LOW LEVEL WIND FIELD WILL CONTINUE THIS EVENING...WHICH SHOULD ALLOW BAND TO BE SHORT LIVED. NO ACCUMULATION EXPECTED WITH SHORT FETCH LESS THAN 30 MILES. .CHI...NONE

RATZER



TSTMS TOUCHED OFF AT THE COAST THIS EVENING AS THE TROF MOVES THRU. QUITE A FEW LTG STRIKES ARND KHQM ARND 03Z...THEN TSTMS RATHER QUICKLY BECAME ISOLD. SCT MDT SHWRS CONT THIS EVENING. ALTHOUGH HAVE NOT SEEN ANY RECENT STRIKES WILL KEEP THE CHC OF TSTMS IN THE FCST FOR TNGT. GUSTY SLIES OCCURRED WITH THE SHOWERS ON THE COAST THIS EVENING...AND ALTHOUGH WND PGTSND HAS BEEN ELY 15KT...AN ACARS SOUNDING SHOWS SLY 40KT 3KFT. SO WILL PROBABLY MIX THAT DOWN A BIT HERE FOR DVLPG SLIES. SO ALTHOUGH SFC PRESGRAD ACTUALLY REMAINS NELY TNGT XPCT SLIES...AND SLIES CERTAINLY PICK ON SUN THRU WRN WA AS THE ONSHORE FLOW INCREASES. THE LAST SHRTWV COMES THRU SUN EVENING...AND WITH IT THE SECOND BATCH OF COOLER AIR ALF...BUT -4C H850 AND LESS THAN IMPRESSIVE WLIES ALF SO CANT GET TOO EXCITED ABOUT ADVERTISING THE LOWERING SNOW LVL...AGAIN...WILL LET THE SPS COAST...SHUD BE PRETTY HARD TO GET ANY SNOW TO STICK DOWN ARND 2KFT OVER THE PASS. SHUD BE A PSCZ ON MON. NO SGFNT CHG TO FCSTS. MCFARLAND

88D GVG MULTIPLE SOFTWARE ERRORS...NO ESTIMATE FOR A RESTART. UIL 9877 SEA 8756 OLM 8766

.SEW...SMALL CRAFT ADVISORY COAST AND W ENTRANCE TO THE STRAIT. .KATX...NOT OPERATIONAL.



VARYING DEPTHS TO THE MARINE LAYER THIS EVENING. 00Z VBG SOUNDING SHOWS A DOUBLE INVERSION...ONE AT ABOUT 750 FEET...AND ANOTHER AT 2000 FEET. LOW LEVEL ACARS DATA NOT AVAILABLE THIS EVENING ALONG LAX COUNTY COAST. HOWEVER...CEILINGS OVER THIS REGION RANGED FROM 800 FEET AT SMO TO 2500 FEET OVER THE ORANGE COUNTY BORDER AT SNA. ACARS SOUNDINGS FOR ONTARIO SHOWED MARINE LAYER DEPTH OF 2800 FEET. AT ANY RATE...LOW CLOUDS INTO CENTRAL COAST AND SANTA YNEZ VALLEY... THE VTU COUNTY COAST...AND LAX COUNTY COAST AND SAN GABRIEL VALLEY THIS EVENING. S SBA COUNTY COAST CLOUD FREE WITH MODERATE SUNDOWNER WINDS THIS EVENING. CLOUDS ASSOCIATED WITH A DYING PACIFIC FRONT WERE OFF THE CENTRAL COAST AND SHOULD MOVE INLAND OVERNIGHT...SO MOST OF SLO/SBA COUNTIES SHOULD HAVE SOME DEGREE OF CLOUDINESS OVERNIGHT. ONSHORE GRADIENTS CONTINUE S OF POINT CONCEPTION...SO ALL COAST AND VALLEY AREAS OF LAX/VTU COUNTIES SHOULD HAVE LOW CLOUDS AND FOG DEVELOP OVERNIGHT.

A BROAD WEST TO SOUTHWEST FLOW WILL PREVAIL OVER THE DISTRICT THROUGH SUNDAY. A WEAK UPPER DISTURBANCE WILL PUSH INTO THE REGION SUN NIGHT THEN MOVE SLOWLY EAST ON MON. THIS RATHER WEAK FEATURE WILL HELP INCREASE THE NORTH TO SOUTH GRADIENTS ACROSS THE DISTRICT...AND IT APPEARS THE SBA COUNTY S COAST AND MOUNTAINS SHOULD HAVE A STRONGER SUNDOWNER-TYPE EVENT SUN NIGHT. WITH INCREASING NW WINDS IN THE OUTER WATERS...IT LOOKS LIKE AN EDDY WILL GET SPUN UP SUN NITE AND EARLY MON. THE REMNANTS OF THAT FRONT MAY GIVE PORTIONS OF SLO/SBA COUNTIES DRIZZLE OR EVEN LIGHT SHOWERS MAINLY SUN MORNING. OTHERWISE...LOW CLOUDS WILL GIVE WAY TO PARTLY CLOUDY SKIES SUN. WITH AN EDDY AND DEEPENING MARINE LAYER...MORE EXTENSIVE LOW CLOUDS SHOULD AFFECT THE LAX COUNTY COAST AND VALLEYS SUN NITE INTO MON MORNING...WITH THE POSSIBILITY OF DRIZZLE AS WELL. BUT WITH NORTHERLY FLOW OVER REST OF THE DISTRICT...LOW CLOUDS SHOULD BE MORE PATCHY IN NATURE...EXCEPT AREAS OF LOW CLOUDS AND POSSIBLE LIGHT SHOWERS ON THE NORTH SLOPES. AS THE UPPER TROF MOVES EAST MONDAY...NORTHERLY WINDS WILL INCREASE OVER NORTHERN PARTS OF THE DISTRICT...BUT OVER LAX COUNTY...ONSHORE FLOW SHOULD KEEP AT LEAST PARTLY CLOUDY SKIES OVER THE REGION. DAYTIME HIGH TEMPS THROUGH MON WILL REMAIN BELOW NORMAL.

MINOR ZONE UPDATE BY 930 PM MAINLY TO ADJUST SOME WORDING IN THE FIRST PERIOD. OTHERWISE REMAINDER OF ZONES LOOK REASONABLE.

IN THE EXTENDED...SOME OFFSHORE FLOW WILL GIVE THE DISTRICT A MUCH WARMER DAY...ESPECIALLY INLAND. AN UPPER RIDGE WILL BUILD WELL OFF THE COAST WED AND THU...WITH SOCAL ON THE EASTERN PERIPHERY OF THE HIGH WITH NORTHERLY FLOW ALOFT. SOME MID AND UPPER LEVEL MOISTURE SHOULD CAUSE PARTLY CLOUDY SKIES MOST EVERYWHERE TUE AND WED...BUT TEMPS WILL STILL BE RATHER MILD FOR THE MOST PART.

LAX 0000. SIRARD.

.LAX...NONE



...SYNOPSIS... ONSHORE FLOW AND A DEEP MARINE LAYER WILL BRING EXTENSIVE NIGHT AND MORNING LOW CLOUDS WEST OF THE MOUNTAINS THROUGH MONDAY WITH ONLY PARTIAL AFTERNOON CLEARING IN SOME AREAS. SOME DRIZZLE IS EXPECTED SUNDAY NIGHT INTO MONDAY DUE TO WEAK LOW PRESSURE ALOFT AND THE MARINE LAYER. HIGH PRESSURE ALOFT WILL DEVELOP BY MID-WEEK TO BRING BETTER AFTERNOON CLEARING OF THE LOW CLOUDS AND WARMING...ESPECIALLY INLAND.

...DISCUSSION... LOW CLOUDS NEVER DISSIPATED THIS AFTERNOON ALONG MOST OF THE SAN DIEGO COAST. NOW...THEY COVER EVERYWHERE WEST OF THE MOUNTAINS EXCEPT FOR A TINY PART OF NW ORANGE COUNTY AND THE MIDDLE PART OF THE INLAND EMPIRE. THE MARINE LAYER...BASED ON ACARS SOUNDINGS AND THE 00Z NKX SOUNDING...IS NOW ABOUT 2500 FEET DEEP. THE STRONG ONSHORE FLOW...NOW 7-8 MB ONSHORE TO THE DESERTS...AND CURRENT RAPID INLAND ADVANCEMENT OF THE LOW CLOUDS INDICATE THAT THIS COULD DEEPEN EVEN BEFORE THE EDDY FORMS OVER THE COASTAL WATERS SUNDAY NIGHT. SUNDAY SHOULD ALSO SEE SOME PARTIAL AFTERNOON CLEARING DUE TO THE HIGH RH THROUGHOUT THE VERTICAL EXTENT OF THE MARINE LAYER.

A VORT MAX ASSOCIATED WITH A SHORTWAVE IS STILL PEGGED TO MOVE BY TO THE NORTH ON MONDAY...SO THAT WILL COMBINE WITH THE EDDY TO PRODUCE A REALLY DEEP MARINE LAYER...POSSIBLY TO 5000 FEET. WITH THAT VERTICAL EXTENT OF THE MOISTURE WITHIN THE MARINE LAYER...AREAS OF DRIZZLE SHOULD OCCUR SUNDAY NIGHT AND MONDAY MORNING. AREAS TO THE NORTH START TO TREND OFFSHORE MONDAY...BUT THIS COULD BE DELAYED AS BOTH ETA/AVN INDICATE A SECONDARY VORT MAX PROLONGING THE TROUGHINESS OVER THE AREA. THE OFFSHORE FLOW MONDAY NIGHT/TUESDAY SHOULD BE ENOUGH TO CLEAR OUT THE INLAND EMPIRE...ALBEIT BRIEFLY AROUND TUESDAY...THOUGH COASTAL AREAS SHOULD STILL SEE LOW CLOUDS AND FOG. WITH HIGH PRESSURE BUILDING IN FROM THE WEST BY ABOUT WED...THE LOW CLOUDS SHOULD BECOME MORE OF A COASTAL EVENT AND BE LESS WIDESPREAD IN THE VALLEYS.

IN THE UPDATE...I REMOVED THE VARIABLE HIGH CLOUDS FROM THE SUNDAY PERIOD...SINCE IT LOOKS LIKE THEY WILL PASS BY TO THE NORTH. ALSO...I ADJUSTED SOME TEMPS...ESPECIALLY THE TOO-COOL UPPER DESERT HIGHS...AND MADE MINOR ADJUSTMENTS ON THE LOW CLOUDS. SAN 0000

.SAN...NONE.

MAXWELL