Forecast Discussions mentioning "ACARS", "MDCRS", or "AIRCRAFT" received at FSL on 01/21/02

OFFSHORE GRADIENTS RELAXED A BIT TODAY AND TREND WILL CONTINUE OVERNIGHT. GUSTY WINDS STILL SHOWING UP IN OBS FROM THE CENTRAL COAST AND LA/VTU VALLEYS AND MOUNTAINS SO WILL MAKE MENTION OF THESE THROUGH THE EARLY EVENING. UPPER SUPPORT FOR WINDS HAS DIMINISHED...SO EXPECT LITTLE TO NO WINDS BY MORNING. ACARS SHOWS INVERSION AROUND 2500 OR SO...BUT SURFACE BASED INVERSION SHOULD SET UP OVERNIGHT DUE TO RADIATIONAL COOLING. WITH MOSTLY CLEAR SKIES TONIGHT...AND IF THE WINDS GO CALM...MAY SEE SOME CHILLY OVERNIGHT LOWS. NOT TO CONCERNED ABOUT LOW CLOUDS AND FOG TONIGHT DUE TO DRY AIRMASS AND RELATIVELY LOW DEWPOINTS. TEMPS TOMORROW WILL DIP SLIGHTLY...FOREWARNING OF A COOL TUESDAY.

PATTERN WILL BEGIN TO CHANGE MONDAY WITH THE APPROACH OF A VIGOROUS SHORTWAVE TOWARD THE CENTRAL COAST. GRADIENTS SHOULD RETURN ONSHORE BY THE AFTERNOON ALONG WITH FALLING HEIGHTS. CENTRAL COAST SHOULD START TO SEE AN INCREASE IN CLOUD COVER MONDAY AFTERNOON. ACROSS LA/VTU COAST AND VALLEYS...MARINE LAYER SHOULD FILL IN NICELY MONDAY EVENING. SYSTEM LOOKS MOISTURE STARVED BUT IS VERY COLD...SO SNOW LEVELS ACROSS THE MOUNTAINS COULD DIP LOCALLY DOWN TO 3500 FEET. CENTRAL COAST CLOSEST TO THE MAIN DYNAMICS OF THE SYSTEM...SO INCREASED POP NUMBERS PUT IN BY THE MID SHIFT GOOD CALL. SOUTH OF POINT CONCEPTION...SLIGHT CHANCE NUMBERS WILL SUFFICE AS THE TAIL END OF THE SYSTEM INTERACTS WITH A HEALTHY MARINE LAYER. WITH LACK OF MOISTURE AND SPEED OF SYSTEM...BEST SHOT OF SHOWERS IS TUESDAY MORNING...WITH PARTY OVER BY THE AFTERNOON. SOME STRONG WINDS BLOWING BEHIND THE FRONT...SO EXPECT BREEZY/WINDY CONDITIONS TO DEVELOP TUESDAY AFTERNOON.

WEDNESDAY LOOKS LIKE A COOL OFFSHORE REGIME WITH A MARGINAL INCREASE IN TEMPS. WITH RIDGING BUILDING IN OVER HEAD ALONG WITH CONTINUING OFFSHORE FLOW OVER THE LATTER HALF OF THE WEEK...WILL SEE A COUPLE OF DAYS RELIEF FROM COOL WEATHER THURSDAY AND FRIDAY. UPPER HIGH SLACKS OFF OVER THE WEEKEND ALONG WITH A RETURN OF ONSHORE GRADIENTS...THUS RETURN OF MARINE LAYER AND LOW CLOUDS/FOG.

LAX 0002. TANABE

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



OFFSHORE FLOW MORE NOTICEABLE THIS MORNING...ESPECIALLY ACROSS THE MOUNTAINS WHERE ISOLATED GUSTS OVER 50 MPH SHOWED IN THE OBS. LAX-DAG GRADIENT HAS MAINTAINED NEAR -3 MB THROUGH THE MORNING...AND WILL LIKELY REMAIN IN THAT NEIGHBORHOOD THROUGH MONDAY MORNING. UPPER LEVEL SUPPORT ANOTHER STORY. ACARS AND PROFILER DATA INDICATE WEAKENING WINDS ALOFT...CORRESPONDING FAIRLY WELL WITH MODEL PROGS OF WEAKENING UPPER SUPPORT TODAY. SO WINDS WILL GRADUALLY DECREASE THROUGHOUT TODAY...AND GRADIENTS ALONE WILL PROBABLY NOT BE ENOUGH TO PRODUCE ANY WINDS OF NOTE OVERNIGHT. TEMPS LOOK ON TRACK...WITH GOOD WARMING WEST OF THE MOUNTAINS AND A FEW DEGREES COOLING WITH THE OFFSHORE FLOW ACROSS THE MOUNTAINS AND DESERTS. WITH MOSTLY CLEAR SKIES TONIGHT...AND IF THE WINDS GO CALM...MAY SEE SOME CHILLY OVERNIGHT LOWS.

GRADIENTS WILL RETURN ONSHORE BY TOMORROW AFTERNOON...ANNOUNCING THE START OF COOLER WEATHER EXPECTED MONDAY AND TUESDAY. FOCUS DURING THIS PERIOD WILL BE A VIGOROUS SHORTWAVE EXPECT TO MOVE ACROSS CENTRAL CALIFORNIA. WITH LOWERING HEIGHTS...EXPECT MARINE LAYER TO FILL IN SOUTH OF POINT CONCEPTION MONDAY NIGHT. UPGRADE TO CHANCE POPS ACROSS THE CENTRAL COAST BY THE MID SHIFT LOOKS REASONABLE. SOUTH OF POINT CONCEPTION...MARINE LAYER MAY PROVIDE ENOUGH MOISTURE FOR COLD FRONT DYNAMICS TO SQUEEZE OUT SOME LIGHT SHOWER TUESDAY MORNING. THERE IS AN AREA OF STRONG WINDS BEHIND THE EXPECTED FRONT...WHICH WILL HELPS TO CLEAR/MIX THINGS OUT TUESDAY AFTERNOON THROUGH THE EVENING. SNOW LEVELS ACROSS THE MOUNTAINS WILL BE FAIRLY LOW...POSSIBLE SINKING BELOW 4000 FEET.

CURRENT ZONES LOOK GOOD...NO NEED TO UPDATE.

LAX 000. TANABE

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



SNOW COVER, CLOUD COVER AND LATEST ACARS SOUNDINGS SUPPORT KNOCKING TEMPS DOWN A CATEGORY IN THE NORTHERN TWO ZONES GROUPS.

KAPLAN



.SYNOPSIS...COOL MOIST AIR WILL STREAM INLAND FROM THE PACIFIC THROUGH TUESDAY. THIS WILL BRING SHOWERS TO THE LOWLANDS AND SNOW TO THE MOUNTAINS. THE SHOWER ACTIVITY WILL DIMINISH MONDAY NIGHT AND TUESDAY AS THE JET SINKS SOUTH INTO CALIFORNIA. A WEATHER SYSTEM ON WEDNESDAY WILL BE THE BEGINNING OF A WET AND WARM THREE DAYS WITH A STRONGER SYSTEMS MOVING INTO THE AREA ON THURSDAY AND FRIDAY.

.DISCUSSION...WSR-88D SHOWS CONVERGENCE ZONE STILL IN PLACE FROM EAST ENTRANCE OF THE STRAIT EASTWARD TO THE CASCADES. ACARS SOUNDING HAVE WSWLY FLOW ALOFT OVER THE PUGET SOUND REGION AND THIS COMBINED WITH THE CONVERGENCE ZONE TO THE NORTH HAS LEFT A NICE BREAK IN THE CLOUDS OVER THE CENTRAL SOUND. NOT MUCH DIFFERENCES IN THE MODELS WITH THE MESO MODELS SHOWING BETTER RESOLUTION ON THE PRECIPITATION LATE MONDAY INTO TUESDAY. 850 MB WINDS SLOWLY DECREASE TONIGHT AND AVALANCHE DATA INDICATING PRECIP IN THE MOUNTAINS RUNNING LESS THAN A TENTH OF AN INCH AN HOUR RIGHT NOW. WILL DOWNGRADE WINTER STORM WARNING TO A SNOW ADVISORY. SATELLITE IMAGERY ALREADY SHOWING THE COLD AIR IN THE GULF BEGINNING TO DIG SOUTH NR 140W. MODELS HAVE BEEN CONSISTENT IN DIGGING THE TROUGH ALONG THE WEST COAST AND BY 00Z TUE THE JET IN OVER NORTHERN CALIFORNIA. 850 MB TEMPS DROP DOWN TO -6C ON MONDAY NIGHT AND TUESDAY AND WITH THE ONSHORE GRADIENT DIMINISHING THIS WILL PUSH THE SNOW LEVEL TO NEAR 500 FEET MONDAY NIGHT AND TUESDAY. ON THE FLIP SIDE BY THEN MOST OF THE DYNAMICS WELL SOUTH OF THE AREA WITH THE JET THIS WILL DECREASE THE SHOWER ACTIVITY OVER THE INTERIOR. FIRST IN A PAIR OF WARM ADVECTION SYSTEMS MOVING INTO THE AREA ON WEDNESDAY. .EXTENDED...EXTENDED MODELS BECOMING A LITTLE MORE PROGRESSIVE WITH THE PATTERN. BAROCLINIC ZONE SETTING UP ON THURSDAY LOOKS LIKE TROUBLE WITH 850 MB TEMPS ABOVE 0 AND MODEL 850 MB WINDS 50-60 KT. TOO EARLY TO ISSUE A ESF BUT RIGHT NOW WITH THE NOW ELEVATION SNOWS THIS HAS THE POTENTIAL TO BE A FLOOD PROBLEM LATE IN THE WEEK. COLD FRONT DRIVES THROUGH THE AREA FRIDAY WITH ANOTHER COOL TROUGH SETTING UP FOR NEXT WEEKEND. FELTON

UIL ++66 SEA 7643 OLM 8843

.SEW...SNOW ADVISORY TONIGHT OLYMPICS...WEST SLOPES NORTH AND CENTRAL CASCADES AND PASSES. .HIGH SURF ADVISORY TONIGHT THROUGH MONDAY NIGHT. .SMALL CRAFT ADVISORY WINDS ALL WATERS.

.KATX...VCP21/CSR21...OPERATIONAL.



.SYNOPSIS...COOL MOIST AIR WILL STREAM INLAND FROM THE PACIFIC TODAY THROUGH TUESDAY. THIS WILL BRING SHOWERS TO THE LOWLANDS AND SNOW TO THE MOUNTAINS. THE FLOW WILL BE STRONG ENOUGH TODAY TO GIVE HEAVY SNOW TO THE MOUNTAINS...PARTICULARLY THE CENTRAL CASCADES.

.DISCUSSION...SATELLITE IMAGERY SHOWS BAROCLINIC BAND OVER SOUTHERN PORTION OF THE AREA WITH A STRONG CONVERGENCE ZONE EXTENDING FROM THE EAST ENTRANCE TO THE STRAIT EASTWARD INTO THE CASCADES. ACARS SOUNDINGS SHOW STRONG 30-40 KT WINDS RIGHT OFF THE GROUND OVER THE PUGET SOUND. THIS COMBINED WITH STRONG SOUTHERLY GRADIENTS SHOULD KEEP THE CONVERGENCE ZONE NORTH OF THE METRO AREA TODAY. STRONG WINDS ALOFT ALSO PROVIDING GOOD OROGRAPHICS IN THE MOUNTAINS. WILL KEEP WINTER STORM WARNING GOING. PLENTY OF COLD AIR ON THE SATELLITE IMAGERY STREAMING OFF THE ALEUTIANS ISLANDS INTO THE GULF OF ALASKA NEAR 50N 140-150W. THIS POOL OF COLD AIR WITH 850 MB TEMPS OF -6 WILL REACH THE AREA TONIGHT AND REMAIN OVER THE AREA ON MONDAY. ONSHORE GRADIENTS SLOWLY WEAKEN ON MONDAY. THIS COMBINED WITH THE COLD AIR WILL PUSH THE SNOW LEVEL TO NEAR 500 FEET MONDAY NIGHT AND TUESDAY. ON THE FLIP SIDE BY THEN MOST OF THE DYNAMICS WELL SOUTH OF THE AREA WITH THE JET MOVING INTO NORTHERN CALIFORNIA BY 00Z TUE. THIS WILL DECREASE THE SHOWER ACTIVITY OVER THE INTERIOR BUT GOOD OROGRAPHICS CONTINUE IN THE MOUNTAINS. LITTLE CHANGE TO THE CURRENT FORECAST. FELTON

UIL +++ SEA 888 OLM 988

.SEW...WINTER STORM WARNING TODAY OLYMPICS...WEST SLOPES NORTH AND CENTRAL CASCADES AND PASSES. .GALE WARNING COAST...STRAIT...PUGET SOUND/HOOD CANAL. .HIGH SURF ADVISORY TONIGHT AND MONDAY. .SMALL CRAFT ADVISORY ADMIRALTY INLET...N INLAND WATERS.

.KATX...VCP21/CSR21...OPERATIONAL.