Forecast Discussions mentioning ACARS, received at FSL on 01/24/01

SYNOPSIS...WEDNESDAY WILL BE MILD ACROSS UTAH AHEAD OF AN APPROACHING PACIFIC STORM. THE STORM WILL SPREAD RAIN AND SNOW ACROSS UTAH WEDNESDAY NIGHT AND THURSDAY. THE SNOW MAY BE HEAVY AT TIMES FOR THE HIGHER ELEVATIONS OF SOUTHWEST UTAH.

DISCUSSION...NEW ETA AND EARLY PANELS OF NEW AVN APPEAR VERY CONSISTENT WITH PREVIOUS RUNS IN BRINGING THE TROF TAHT IS APPROACHING THE COAST ACROSS OUR AREA WED NIGHT AND EARLY THU. NO REAL ARGUMENTS WITH THIS BUT MILD CONCERN ON TIMING. THE INITIAL PANELS OF BOTH THE ETA AND AVN AT 00Z PUT THE MAX WINDSPEED AT 300MB NEAR 36N/135W. SATELLITE IMAGERY SUGGESTS IT MIGHT BE CLOSER TO 40N/140W AND INDEED THE STRONGEST AIRCRAFT REPORT IS AT ABOUT 39N/140W. THAT JET PUSHING UNDER THE TROF WILL BE THE MECHANISM TO MOVE IT EAST SO IF THE MODELS ARE A LITTLE TOO FAR EAST WITH IT THEY MAY BE A LITTLE FAST ON THE MOVEMENT OF THE TROF. WHILE WE ARE ONLY TALKING A FEW HOURS DIFFERENCE AND NO REAL DIFFERENCE IN THE ULTIMATE RESULTS IT COULD MAKE THE DIFFERENCE BETWEEN PRECIPITATION STARTING IN SOUTHWEST UT LATE WED OR WAITING FOR THE WED NIGHT PERIOD. FOR NOW THE FORECASTS HAVE THE TREND AND RELATIVE INTENSITIES HANDLED JUST FINE SO NO NEED TO MAKE CHANGES FOR LATE SECOND OR THIRD PERIOD TIMING. THE INTERIM LOOKS FINE WITH SOME HIGH CLOUDS MOVING ACROSS THE AREA NOW WHICH WILL BE FOLLOWED BY A BRIEF PERIOD OF CLEARING LATER TONIGHT THEN INCREASING CLOUDS ON WED. DONT PLAN ANY CHANGES TO THE WINTER STORM WATCH OR THE IDEAS EXPRESSED IN THE SPECIAL STATEMENT.

SLC 0157 CDC 0476 SANDERS

.SLC...WINTER STORM WATCH FOR WEDNESDAY NIGHT AND THURSDAY SOUTHWEST AND HENRY MOUNTAINS...SOUTH-CENTRAL...WEST-CENTRAL AND SOUTHWEST VALLEYS...UT ZONES 15>18 AND 20. ...SPECIAL WEATHER STATEMENT ALL OTHER ZONES.



.TDY AND THU...

WATER VAPOR IMAGERY INDICATES A SHORTWAVE EJECTING INTO CALIFORNIA. AN UPPER LEVEL LOW WAS OFF THE WA/ORE COAST WITH A RIDGE OVER THE ROCKIES. FOG/STRATUS SATELLITE IMAGERY AND SURFACE OBSERVATIONS INDICATE FOG MAINLY IN THE EAST. SURFACE OBSERVATIONS AT 07Z ALSO INDICATE DRAINAGE WIND AT BILLINGS...BUT NOT AT LIVINGSTON.

THE 00Z ETA AND THE AVN BOTH INITIALIZED WELL...WHEN COMPARED TO HIGH DENSITY WINDS...RADIOSONDE DATA...AND ACARS DATA PER THE NUMERICAL WEATHER PREDICTION INITIALIZATION PAGE FROM U OF WA. THE MODELS ARE SIMILAR UP TO 36 HOURS BEFORE THERE IS SIGNIFICANT DIVERGENCE. BASED ON BETTER RUN TO RUN CONSISTENCY...WILL FOLLOW THE 00Z AVN.

TODAY...UPPER LEVEL RIDGE MOVES SLOWLY EAST ACROSS THE HIGH PLAINS FOR DRY WEATHER. WITH A BIT OF TIGHTENING OF THE GRADIENT IN THE EAST... GOOD LOW LEVEL SUBSIDENCE...AND WARM AIR ADVECTION AT 850 MB WILL BUMP UP TEMPERATURES MORE IN THE EAST.

TONIGHT...ANOTHER SHORTWAVE GETS EJECTED INTO THE DESERT SW AS THE RIDGE PROGRESSES INTO THE CENTRAL U.S. WITH WEAK DYNAMICS OVER THE COUNTY WARNING AREA. MOISTURE GETS ADVECTED FROM THE SW FOR INCREASING CLOUDS...FROM THE WEST.

THURSDAY...WEAK TROFFING MOVES OVER THE AREA WITH WEAK DYNAMICS AND WEAK DIVERGENCE. BEST DYNAMICS REMAIN WELL TO THE SOUTH OF THE CWA IN SPLIT FLOW. MAIN UPPER LEVEL LOW REMAINS OFF THE PACIFIC NW COAST. NORTHERLY FLOW IN BACKSIDE OF LOW LEVEL TROF INCREASES UPSLOPE...IN ADDITION TO COLD AIR BEING DRAWN SOUTH. AT THE SURFACE WEAK LOW PRESSURE DEVELOPS IN WYOMING. THIS...IN COMBINATION WITH A SURFACE HIGH IN ALBERTA WILL ALSO INCREASE THE UPSLOPE FLOW. WILL GO SCATTERED IN THE WEST AND CENTRAL PORTIONS OF THE CWA...AND ISOLATED IN THE EAST. STROBIN

.FRI...SAT...SUN...MON...TUE... NEW AVN TAKES A SOUTHWARD MOVING 700MB TROUGH THROUGH THE AREA THURSDAY NIGHT. UPSLOPE FLOW DEVELOPS INTO EARLY FRIDAY AS THE TROUGH SINKS SOUTH. WILL INCLUDE A THURSDAY NIGHT PERIOD...AS LOOKS LIKE THIS IS THE BEST CHANCE OF SNOW COMPARED TO FRIDAY. WILL KEEP THE CHANCE OF SNOW SHOWERS AROUND FOR FRIDAY...AS LINGERING STUFF COULD BE SLOW TO CLEAR IN THE MORNING. DRIER AIR WORKS DOWN FROM THE NORTH FRIDAY AFTERNOON AND INTO THE WEEKEND AS DEEP UPPER LOW DIGS INTO ARIZONA. HUMPHREY

TDY THU FRI SAT SUN MON TUE ------------------------------------------------------- BIL 040 024/038 021/034 018/037 020/044 025/044 025/032 0/U 03/J 44/S 21/E 00/B 11/E 33/S LVM 037 024/035 018/030 016/035 019/045 024/044 027/030 0/B 04/S 44/S 21/E 00/B 11/E 33/S HDN 040 022/039 020/035 017/037 019/045 025/044 024/033 0/U 03/J 44/S 21/E 00/B 11/E 33/S MLS 032 015/034 023/035 018/032 016/041 017/041 024/033 0/U 02/E 43/J 21/E 00/B 11/E 33/S 4BQ 033 016/035 022/035 017/030 016/040 016/040 022/034 0/U 02/E 43/J 21/E 00/B 11/E 33/S BHK 030 013/032 020/033 015/029 013/038 014/040 018/030 0/U 02/E 43/J 21/E 00/B 11/E 33/S SHR 033 015/035 021/035 016/035 015/035 021/041 024/038 0/U 02/J 44/S 21/E 00/B 11/E 33/S