Forecast Discussions mentioning ACARS, received at FSL on 01/23/00

MAIN FCST PROBLEMS THIS AM ARE WHAT TO DO WITH THE ADVISORIES (AND WARNINGS)...

MOST ZNS NOW HAVE WINDS BLO WIND ADV CRITERIA. LOOKING AT THE 22/12Z GYX RAOB...AS WELL AS ACARS RAOB FM PWM AND SFC GEOS WINDS...BLV THE BEST WINDS WL STAY ABV THE INVERSION (WHICH LUKS TO BE ABT 925 MB). THERE MAY BE SUM HIER GUSTS IN THE HIER TRRN...BUT WL HANDLE THAT WITH A GUST MENTION IN THE ZNS. SO...WL LET THE WIND ADVISORY DROP WITH THE UPDATE.

NEXT ARE THE WIND CHILL ADVISORY/WIND CHILL WARNINGS. IR/VIS LOOPS SHOW A PATCH OF MOSTLY CI/AC ACRS WRN/SRN ME...AND THE BACK EDGE LUKS TO EXTRAPOLATE TO THE CST AFT 18Z...SO THIS WL AFFECT THE MAXES FOR WRN ME (THAT IS TO LOWER THEM). WITH THIS IN MIND...AND CONSIDERING THE WINDS WL NOT BE QUITE AS STG AS EARLIER LAST NGT... WL BACKPEDAL TO WIND CHILL ADVISORY FOR ALL BUT THE WRN ME AND NRN NH MTNS. WL LEAVE THE WARNINGS IN PLACE HERE SINCE MOST OF THESE LOCATIONS MAY NOT SEE ZERO. COORD WITH BOX/CAR/BTV ON THE WIND CHILL STUFF.

AS FOR CLDS...QUITE A BIT OF OF CI/AC SPILLING SWD FM ARND THE INTENSE LO. MAY STEP BACK ON THE SKIES TO P/SUNNY FOR MOST ZNS.

NO CHANGES TO THE REMAINDER OF THE FCST.

WITH THE QUICKER MOVMNT OF THE WAA CLDS/PCPN FOR SUN NGT...WL GO WITH JUST PCPN AND KNOCK OUT THE MENTION OF CLDS (THANKS WALT).

.GYX...WIND CHILL WARNING THIS AFTN MEZ007>009-NHZ001-002 WIND CHILL ADV ALL REMAINING ZNS FOR THIS AFTN GLW

HAYES

SPLIT FLOW NR 150W CONTINUES W/NRN BRANCH COMING ARND HI CNTRD NRN B.C....AND SRN BRANCH COMING ARND 35N/140W LOW AND INTO CA. 12Z MDLS FCST SPLIT TO PERSIST THRU EARLY MON THEN BEGIN WKNG AND PROGRESSING EWD. MEDIUM RANGE MDLS ARE HAVING PROBLEMS RESOLVING THE DETAILS IN BREAKING DOWN THE SPLIT AND TRANSITIONING TO CONSOLIDATED WLY FLOW ACRS THE NE PAC.

LOTS OF CLDS OVR CNTRL/N PGTSND THIS AFTN...AS THE RAIN BAND THAT MOVED UP INTO THE AREA EARLY THIS MORNING HAS BEEN SLOWED BY THE WEAK WAVE MOVG DOWN THRU B.C. SCT SHWRS FINALLY DSIPTG CNTRL PGTSND WITH BREAKS OCCURRING OVR SW INTR AND SMALL BREAKS PGTSNT. SFC GRADS WKLY OFSHR ATTM BUT RESIDUAL WND DIRECTIONS STILL ALL OVER THE PLACE. ACARS REPS SHOW LOW LVL WINDS STILL SW 10KT. CLDS WL BE SLOW TO DSIPT...BUT GRDL DRYING TREND STILL OK...AND SHOULD CONT THRU AT LEAST MID MONDAY. HOWEVER WL HOLD 20 PCT POP FOR CST THRU MON GIVEN PROXIMITY OF LOW OFF CST AND SCT SHWRS STILL ROTATING ARND IT.

12Z MDLS A LITTLE FASTER IN BRINGING MSTR UP IN SW FLOW LATE SUN AND MON. SIGNIFICANT DIFFERENCES IN RH FIELD FOR W WA BTWN ETA AND AVN AT 48HRS. AVN HAS CHC RAIN MON AFTN...ETA IMPLIES DRY. WL COMPROMISE WITH INCRSG HI CLDS AFTN FOR CNTRL AND S PARTS.

EXTENDED...TUE-THU. CONFIDENCE LOW...ESPECIALLY WED/THU...THUS BROADBRUSH TYPE FCST. ALL MDLS HAVING SOME TROUBLE IN RESOLVING AND TIMING THE FIRST FEW FEATURES INTO THE CST AFTER THE BREAKDOWN OF THE SPLIT IN FLOW...CURRENTLY OUT ARND 150W. KAM UIL 3222 SEA 2111 OLM 2111

.KATX...VCP21/CRS21...OPERATIONAL .SEW...NONE.

...SYNOPSIS... AN UPPER TROUGH OF LOW PRESSURE OVER THE EASTERN PACIFIC WILL MOVE INTO CALIFORNIA ON MONDAY AND TUESDAY. SOUTHWEST FLOW AHEAD OF THIS SYSTEM WILL CONTINUE TO SPREAD MID AND HIGH CLOUDS ACROSS SOUTHWEST CALIFORNIA THROUGH MONDAY WITH A CHANCE OF SHOWERS FOR TUESDAY AS THE UPPER TROUGH MOVES CLOSER.

...DISCUSSION... HAVE GENERALLY FOLLOWED THE AVN/MRF IN THE SHORT TERM THROUGH THE EXTENDED WITH MRF NOW IN LINE WITH EURO MDLS THRU THU. SUCH AGREEMENT DOESN'T NECESSARY IMPLY HIGH CONFIDENCE...ESPECIALLY IN A RETROGRESSIVE PATTERN. CLOUD FORECAST CONTINUES TO BE PROBLEMATIC AS MDLS CONTINUE TO HAVE DIFFICULTY WITH THE MSTR FORECASTS. THUS WL USE VARIABLE CLOUD WORDING FOR MOST ZONES...THOUGH WITH SHORT WAVE RDGG ALF BUILDING INTO SW CA MON AHEAD OF THE PAC TROUGH FOR TUE...MANY AREAS COULD SEE A LOT OF SUN ON MONDAY. PATCHY LOW CLOUDS AND FOG WL ALSO OCCUR ALG THE CST INTO THE VLYS THIS MORNING WITH LOW RESOLUTION ACARS SOUNDINGS IMPLYING A WK MARINE INVERSION AROUND 1500 FT...SUFFCIENT FOR PATCHY LOW CLOUDS AND FOG ALG THE CST AND PATCHY DENSE FOG IN THE INLAND VLYS. HAVE INCLUDED 20 PERCENT POPS FOR THE SBD COUNTY MTNS AS THE SRN EDGE OF PRECIP MOVG INTO CNTRL CA THIS MORNING MAY BRUSH THE SBD COUNTY MTNS THIS AFTERNOON AND EVENING. BETTER CHANCE FOR SHOWERS FOR MOST AREAS FOR TUE AS THE AXIS OF HIGHEST PW'S MOVES ACROSS SW CA TUE WITH WK TO LCLLY MDT DYNAMICS. EXPECT THAT AMOUNTS OF SIGNIFICANCE THRU TUE WL GENERALLY BE FM LOS ANGELES N WHERE DYNAMICS AND ONSHR FLOW ARE STRONGER. WITH THICKNESSES WARMING ABOUT 30 METERS EACH OF THE NEXT TWO DAYS AND LOW LVL PRESSURE GRADIENTS TRENDING WKLY OFSHR...TEMPERATURES SHOULD WARM A FEW DEGREES TODAY AND MON.

EXTENDED...TRAILING SHORTWAVES AND RESIDUAL MSTR COULD CONTINUE A CHANCE OF SHOWERS IN THE MTNS FOR WED AND THU. HAVE INCLUDED SOME MENTION OF THIS IN THE ZONES...BUT HAVE TRENDED TOWARD CLIMO FOR THU TO ACCOUNT FOR MDL UNCERTAINTY.

SAN 000

.SAN...NONE.

MARTIN

MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE FOG THIS MORNING AND THE CHANCE OF SNOW TONIGHT WITH THE NEXT UPPER LEVEL FEATURE.

08Z SATELITTE IMAGE AND SURFACE OBS INDICATE DENSE FOG DOMINATING THE REGION THIS MORNING. AFTER MAKING SOME CALLS TO THE AWOS SITES MOST SITES ARE REPORTING VISIBILITIES 1/2 MILE OR LESS. THIS LOOKS TO BE THE TREND FOR THE NEXT SEVERAL HOURS AS THE WEAK SURFACE HIGH REMAINS IN CONTROL OF THE AREA AND ACARS SHOWING SOME WEAK LOW LEVEL WARM AIR ADVECTION IN PLACE. MODELS DO SHOW A WEAK 925 TROF PASSING THROUGH THE AREA BY MID MORNING THIS MAY HELP RAISE THE CIGS SOME AND POSSIBLY THE VISIBILITIES...BUT I AM A BIT SKEPTICAL AT THIS TIME DUE TO A SNOW COVERED GROUND. WE ARE INCLINED TO GO WITH THE DENSE FOG ADVISORY UNTIL NOON...BUT WE WILL WAIT TILL PRESS TIME TO MAKE THAT DECISION. FOR NOW...WE WILL DEFINATELY MENTION THE THREAT OF DENSE UNTIL MID MORNING. AFTER THE FOG LIFTS SOME OF THE COLD AIR ADVECTION WILL TRY WORKING INTO THE AREA. TEMPERATURES SHOULD NOT BUDGE MUCH. THEREFORE...WE ARE GOING TO FOLLOW CLOSEST TO THE FWC NUMBERS.

LATEST SATELITTE IMAGE SHOWS THE NEXT UPPER LEVEL FEATURE DIVING SOUTH THROUGH THE NORTHERN PLAINS. THIS FEATURE IS EXPECTED TO SHARPEN UP THE TROF OVER THE REGION TONIGHT. SOME FRONTOGENISIS WILL ALSO BE IN PLACE AND MAY GET THE CWFA ANOTHER SHOT OF SOME SNOW SHOWERS THIS EVENING. HOWEVER...DUE TO THE FAST MOVEMENT OF THIS FEATURE AND LIMITED LOW LEVEL MOISTURE IT SHOULD NOT AMOUNT TO ANYTHING MORE THAN A COUPLE TENTHS OF AN INCH OF SNOW BEFORE ENDING OVERNIGHT. TEMPERATURES SHOULD FOLLOW FAIRLY CLOSE TO GUIDANCE DUE TO SOME COLD AIR ADVECTION IN PLACE.

TOMORROW THE MODELS SHOW THE LOW LEVELS TRYING TO DRY OUT SOME AS COOL NORTHWEST FLOW PREVAILS AND THE SURFACE HIGH BUILDS IN. WITH LITTLE OR NO ADVECTION IN PLACE TEMPERATURES WILL STILL HAVE A HARD TIME REACHING THE FREEZING MARK.

.SDF...DENSE FOG ADVISORY UNTIL MID MORNING FOR ALL OF CENTRAL KENTUCKY AND A PORTION OF SOUTHERN INDIANA

COX