FXUS65 KBYZ 120411
AFDBYZ
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
911 PM MST FRI DEC 11 2009
.SHORT TERM...VALID FOR SAT AND SUN...
NO CHANGES TO THE WIND ADVISORY OR WINTER STORM WATCH THIS
EVENING.
WIND ADVISORY CONTINUES FOR GAP FLOW AREAS FROM LIVINGSTON TO
NYE. WIND SPEEDS IN LIVINGSTON HAVE BEEN ERRATIC...FROM ADVISORY
LEVELS ONE HOUR TO 20 TO 30 MPH THE NEXT. MODELS NOT HANDLING
PRESSURE GRADIENT AT ALL WELL. LATEST OBSERVATIONS SHOW AN 18MB
GRADIENT ACROSS THE BEARTOOTH MOUNTAINS...WITH SOME STRENGTHENING
LIKELY OVERNIGHT AS 700MB WINDS TURN MORE WESTERLY AND INCREASE
AFTER MIDNIGHT. WARM ADVECTION FROM 850-700MB SHOULD CONTINUE TO
ENHANCE THE LOW LEVEL INVERSION IN THESE AREAS AS WELL ENHANCING
THE CONSTRICTION THROUGH THE NORTHERN RIVER VALLEYS OF THE
BEARTOOTH MOUNTAINS. GIVEN ALL OF THIS WILL NOT MAKE ANY CHANGES
TO THE ADVISORIES AND EXPECT STRONGER WINDS TO RE-DEVELOP
SHORTLY.
THE ONLY CHANGE THIS EVENING WAS TO LOWER TEMPERATURES IN THE
SOUTHWEST MOUNTAINS. COOKE CITY AREA WAS CLOSE TO FORECAST LOWS
AND BUMPED THIS AREA BELOW ZERO TONIGHT. REST OF THE FORECAST ON
TRACK. AS WITH LAST NIGHT OVERNIGHT LOWS ARE TRICKY GIVEN THE
WINDS...CLOUD COVER AND SNOW COVER. A SLIGHT BREAK IN THE CLOUDS
OR WEAKENING OF WINDS FOR EVEN A SHORT PERIOD WILL LEAD TO QUICK
DROPS IN TEMPERATURE. LOWS IN WESTERN AREAS WILL BE IN THE LOWER
20S WITH SINGLE DIGITS EAST. REST OF THE FORECAST IS IN GOOD SHAPE.
CHAMBERS
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
MODELS WERE VERY CONSISTENT ON HAVING MONDAY BEING THE COLDEST
DAY WITH THE NEXT ARCTIC INVASION. THE MODELS WERE SETTING UP A
BAROCLINIC ZONE OVER NORTHERN LOCATIONS. KEPT THE IDEA OF LIKELY
POPS FOR MONDAY. RAISED POPS SOME FOR MONDAY NIGHT AS UPSLOPE
FLOW AND MOISTURE OVER RUNNING THE ARCTIC BOUNDARY CONTINUES. THE
ARCTIC LIFTS OUT VERY QUICKLY ON TUESDAY. TUESDAY WILL BE A VERY
TRICKY DAY FOR TEMPERATURES AS FRESH SNOW COVER WILL BE
COUNTERACTED BY STRONG WARM AIR ADVECTION. SHOULD BE ABLE TO
REACH INTO THE 20S OVER WESTERN AND CENTRAL ZONES...AND MAY EVEN
BE A BIT WARMER. THE EAST WILL BE SLOWER TO REBOUND WITH HIGHS
HELD IN THE TEENS. RIDGING TAKES OVER FOR WEDNESDAY THROUGH
SATURDAY AND THIS WILL PROVIDE A PERIOD OF MILD AND MAINLY DRY
WEATHER. HUMPHREY
&&
.AVIATION...
STRONG SOUTHWEST WINDS AT LIVINGSTON AND NEAR FOOTHILLS HAVE BEEN GUSTING
TO AROUND 50 KTS LATE THIS EVENING...AND ARE EXPECTED TO CONTINUE
OFF AND ON THROUGH THE OVERNIGHT. WINDS SHOULD LET UP BY LATE
MORNING.
VFR FLIGHT CONDITIONS CAN BE EXPECTED OVERNIGHT AND SATURDAY. SOME
SCATTERED SNOW CAN BE EXPECTED OVER THE MOUNTAINS...AS MID LEVEL
MOISTURE MOVES INTO THE AREA...RESULTING IN OCCASIONAL OBSCURATION OF
MOUNTAIN TOPS. GILSTAD
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 014/031 012/014 905/000 907/024 020/035 026/042 027/044
01/E 37/S 66/S 31/B 11/B 11/N 11/B
LVM 017/034 017/022 002/010 007/031 024/037 027/042 031/042
02/J 37/S 66/S 31/E 11/N 11/N 11/N
HDN 007/029 006/016 905/000 908/022 009/035 014/040 017/045
01/B 26/S 66/S 31/B 11/B 11/B 11/B
MLS 001/026 902/007 910/903 916/015 005/028 012/033 016/041
11/E 35/S 53/S 21/B 11/B 11/B 11/B
4BQ 005/029 003/010 906/000 916/018 006/032 015/037 016/045
01/B 24/S 65/S 21/B 11/B 11/B 11/B
BHK 000/025 902/008 910/903 920/013 003/026 010/030 012/039
12/J 24/S 43/S 11/B 11/B 11/B 11/B
SHR 009/034 013/020 901/008 908/025 010/037 015/040 016/044
01/B 24/S 66/S 31/B 11/B 11/B 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH IN EFFECT FROM LATE SATURDAY NIGHT THROUGH
MONDAY AFTERNOON FOR ZONES 28>42-56>58-63>66.
WIND ADVISORY IN EFFECT UNTIL NOON MST SATURDAY FOR ZONES
65-66.
WY...WINTER STORM WATCH IN EFFECT FROM LATE SATURDAY NIGHT THROUGH
MONDAY AFTERNOON FOR ZONE 99.
&&
$$
WEATHER.GOV/BILLINGS
