AREA FORECAST DISCUSSION

 
 FXUS65 KBYZ 232234
 AFDBYZ
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE BILLINGS MT 
 334 PM MST MON NOV 23 2009
 
 .SHORT TERM...VALID FOR TUE AND WED...
 
 STRONG ENERGY WAS PUSHING INTO BRITISH COLUMBIA. THIS WAS CAUSING
 SURFACE PRESSURE FALLS OVER SOUTHWEST CANADA. AS THE ENERGY
 PROGRESSES EAST...THE SURFACE PRESSURE FALLS WILL EXTEND FARTHER
 EAST AND PROMPT A DEEPENING LEE TROUGH OVER MONTANA. WINDS HAVE
 BEEN GUSTY AT LIVINGSTON ALL DAY...BUT NOWHERE NEED ADVISORY TYPE
 OF LEVELS. THE DIRECTION HAS BEEN WESTERLY TOO...WHICH IS NOT
 FAVORABLE FOR ADVISORY TYPE OF WINDS. PATTERN BECOMES A LITTLE
 MORE FAVORABLE TONIGHT AND EARLY TUESDAY. THE SURFACE PRESSURE
 GRADIENT WILL BECOME A LITTLE MORE PERPENDICULAR TO THE UPPER
 YELLOWSTONE VALLEY AFTER MIDNIGHT AS THE HIGHER PRESSURE OVER
 NORTHERN IDAHO ERODES. MODEL SURFACE PRESSURE PATTERN STILL DOES
 NOT LOOK ORIENTATED QUITE RIGHT FOR HIGH WINDS. OPTED TO NOT
 ISSUE AN ADVISORY BUT BUMPED WIND GUSTS A BIT MORE. EVENING CREW
 WILL HAVE WATCH THIS CLOSELY AS THE EVENING WEARS ON. ALSO BUMPED
 UP WINDS OVER THE AREA FROM HARLOWTON TO BIG TIMER. THE GRADIENT
 NOT OVERLY CONDUCIVE FOR HIGH WINDS THERE. WINDS SHOULD STAY
 STRONG INTO TUESDAY MORNING WITH A DECREASE EXPECTED IN THE
 AFTERNOON AS THE LEE TROUGH PULLS OFF THE EAST SLOPES.
 
 SNOW SHOWERS HAVE BEEN AFFECTING THE MOUNTAINS OFF AND ON ALL
 DAY. THE SHORTWAVE ENERGY DRIVING THESE SHOWERS IS PROGGED TO
 SLIDE INTO WYOMING OVERNIGHT. DROPPED POPS FOR THE OVERNIGHT
 HOURS AS AN UPPER RIDGE BUILDS INTO THE STATE. THE STRONG ENERGY
 DEVELOPING THE DEEP LEE TROUGH TONIGHT OVER THE FRONT
 RANGE...WILL DROP INTO EASTERN MONTANA AND WESTERN NORTH DAKOTA
 TUESDAY AFTERNOON. THIS SYSTEM HAS SOME STRONG DYNAMICS BUT
 LIMITED MOISTURE. PAINTED LOW POPS FOR THE NORTHERN LOCATIONS
 TUESDAY AFTERNOON. A COLD FRONT WILL PUSH INTO THE FORECAST AREA
 TUESDAY AFTERNOON AND LAYS DOWN OVER CENTRAL SECTIONS TUESDAY
 NIGHT. THE GFS WAS PRODUCING SOME LIFT ALONG THE BOUNDARY FROM
 HARLOWTON TO SHERIDAN. RAISED POPS FOR CENTRAL ZONES TUESDAY.
 STRONGEST FORCING SWINGS INTO NORTHEAST WYOMING PRETTY
 QUICKLY...SO DID NOT RAISE POPS TOO DRAMATICALLY. AN UPPER RIDGE
 MOVES IN FOR WEDNESDAY. THIS WILL PRODUCE A DRY DAY. HUMPHREY
 
 .LONG TERM...VALID FOR THU...FRI...SAT...SUN...MON...
 
 THE EXTENDED PERIOD BEGINS THANKSGIVING DAY...WITH THE REGION WELL
 COVERED BY AN UPPER LEVEL RIDGE...REMAINING IN CONTROL OVER THE
 REGION THROUGH FRIDAY...BUT BEGINS BREAKING DOWN WITH THE
 APPROACH OF A STRONG UPPER LEVEL TROF AND COLD FRONT THAT EVENING
 AND NIGHT. THIS SYSTEM HAS COME INTO MUCH BETTER AGREEMENT IN THE
 MODELS WITH THE 12Z RUN...AND SEEMS TO SPREAD POPS ACROSS THE
 REGION THROUGH SUNDAY...WITH SOME LINGERING SHOWERS IN THE EAST
 SUNDAY NIGHT. BEGINNING AS A TROF MOVING IN FRIDAY NIGHT...BOTH
 SEEM TO FORM A DOUBLE BARREL LOW...ALTHOUGH GFS TAKES A LITTLE
 LONGER TO CUT OFF THE LOWS. EC TAKES A BIT MORE EASTERLY
 TRACK...WHILE GFS DIGS EASTERN LOW THROUGH EASTERN ZONES. GFS HOLD
 TOGETHER THE LOW KEEPING THE AREA IN BETTER POTENTIAL FOR WRAP
 AROUND FLOW THROUGH SUNDAY...WHILE EC BREAKS DOWN THE LOW INTO A
 TROF FAIRLY QUICKLY. MOISTURE AVAILABILITY LOOKS PRETTY GOOD WITH
 BOTH MODELS...AND COULD BE A PRETTY GOOD SHOT FOR EASTERN ZONES
 SUNDAY. SNOW ACCUMULATIONS WILL AGAIN BE A QUESTION MARK OVER THE
 PLAINS REGION...DUE TO RECENT HIGH TEMPS...BUT SNOW OVERNIGHT
 COULD ACCUMULATE PRETTY QUICKLY DUE TO COLD TEMPS EXPECTED. HIGH
 TERRAIN...ESPECIALLY PREFERRED EAST AND NORTH FACE UPSLOPE
 REGIONS...COULD SEE GOOD SNOW ACCUMULATIONS AS THIS SYSTEM MOVES
 THROUGH THE REGION. DID EXTEND POPS ACROSS THE PLAINS THROUGH
 SUNDAY...AND RAISE EASTERN POPS TO SCATTERED RANGE SATURDAY NIGHT
 AND SUNDAY. RIDGE BUILDS IN QUICKLY AGAIN ON THE TAIL OF THIS
 TROF...BRINGING A RETURN TO CLEAR CONDITIONS TO THE REGION.
 
 TEMPERATURE WILL BE WELL ABOVE NORMAL THANKSGIVING DAY AND FRIDAY...WITH
 HIGHS IN THE MID TO UPPER 50S. WITH THE SYSTEM COMING IN FRIDAY
 NIGHT...TEMPERATURES ARE EXPECTED TO BE 10 TO 15 DEGREES COOLER ON
 SATURDAY. SUNDAY WILL BE A BIT COOLER...WITH THE HIGHS AROUND
 NORMAL...IN THE UPPER 30S...BUT TEMPS APPEAR TO RISE BACK ABOVE
 NORMAL MONDAY. GILSTAD
 
 &&
 
 .AVIATION...
 
 UPPER LEVEL TROF WILL COMPLETE PASSAGE THROUGH THE REGION THIS EVENING
 EVENING...WITH SOME LINGERING WEAK SHOWERS IN THE EASTERN ZONES. GUSTY
 WEST TO SOUTHWEST SURFACE WINDS...AROUND 15 KTS WITH GUSTS UP
 TO 25 KTS IN MOST CENTRAL AND WESTERN ZONES ARE EXPECTED THROUGH
 THE EVENING. HIGHER WINDS ARE EXPECTED AROUND KLVM AND NEAR
 FOOTHILLS...SUSTAINED AROUND 25 KTS WITH GUSTS TO AROUND 35 KTS.
 WINDS ARE EXPECTED TO PICK UP LATER TONIGHT AND INCREASE THROUGH
 THE DAY TOMORROW FOR THE KLVM VICINITY AND FOOTHILLS REGIONS...AS
 WELL AS AROUND 3HT AND JUDITH GAP REGIONS...WITH SUSTAINED WINDS
 AROUND 35 KTS...AND GUSTS TO AROUND 45KTS. GILSTAD
 
 
 &&
 
 .PRELIMINARY POINT TEMP/POPS...
 
     TUE     WED     THU     FRI     SAT     SUN     MON     
 -----------------------------------------------------------
 BIL 026/048 030/046 031/056 033/055 032/044 025/038 027/044
     00/N    30/B    00/U    01/B    22/W    21/B    11/B
 LVM 022/044 024/049 025/054 029/048 021/038 019/038 019/039
     00/N    20/B    00/U    02/W    32/J    21/B    11/B
 HDN 022/051 028/050 026/057 029/057 030/047 023/041 024/046
     00/N    30/B    00/U    00/B    22/W    33/J    11/B
 MLS 024/049 024/043 025/056 028/056 031/047 021/039 022/044
     00/N    20/B    00/U    00/U    22/W    33/J    10/B
 4BQ 022/049 025/045 024/056 027/056 031/046 021/037 022/044
     00/B    20/B    00/U    00/U    22/W    33/J    20/B
 BHK 022/047 022/041 021/054 026/054 029/046 019/036 020/040
     00/N    20/B    00/U    00/U    22/W    32/J    10/B
 SHR 019/048 027/045 023/057 026/057 026/044 020/040 022/044
     00/B    30/B    00/U    01/B    22/W    33/J    11/B
 
 &&
 
 .BYZ WATCHES/WARNINGS/ADVISORIES...
 MT...NONE.
 WY...NONE.
 
 &&
 
 

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