Area Forecast Discussion
Issued by NWS Billings, MT

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895
FXUS65 KBYZ 120401
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
901 PM MST THU FEB 11 2016

.UPDATE...
INTERESTING DYNAMICS IN PLACE IN THE ATMOSPHERE TONIGHT. AN
AMPLIFIED RIDGE TO THE WEST WAS SLIDING EAST VERY SLOWLY. THIS WAS
ALLOWING FOR WARM ADVECTION AT THE MID LEVELS WITH THE RIDGE AXIS
SLIDING INTO WESTERN MONTANA OVERNIGHT. THIS WARM ADVECTION WAS
PRODUCING A BAND OF LIGHT PRECIPITATION OVER FAR WESTERN MONTANA
AND NORTHERN IDAHO...GRADUALLY MOVING EAST. THIS WILL ALLOW OUR
WESTERN MOUNTAINS AND LOWER ELEVATIONS TO RECEIVE INCREASING SNOW
SHOWER CHANCES AS THE NIGHT GOES ON. THIS COVERED WELL IN THE
GOING FORECAST.

OVER THE EAST...LOW LEVEL COLD AIR WAS SLIDING IN FROM NORTHEAST
MONTANA. TEMPERATURES AT MLS AND BHK WERE AROUND 30 DEGREES THIS
HOUR WHILE BIL WAS IN THE MID 40S. THIS COLD AIR WILL CONTINUE TO
SLIDE WEST THROUGH THE NIGHT...GETTING INTO BIL OVERNIGHT. MID
LEVEL MOISTURE FROM THE WEST WILL OVER RUN THIS BOUNDARY AND
PRODUCE INCREASING SNOW SHOWER CHANCES OVERNIGHT AND INTO FRIDAY
MORNING. FARTHER EAST...LOW CLOUDS AND FOG...WITH A SLIGHT CHANCE
OF A LIGHT MIX OF PRECIPITATION WILL BE PRESENT IN THE COLDER AIR.
ALL OF THESE WEATHER CONDITIONS WERE HANDLED WELL BY THE CURRENT
FORECAST. TWH

&&

.SHORT TERM...VALID FOR FRI AND SAT...
SHORTWAVE IN EASTERN MT WHICH PRODUCED SNOW SHOWERS AT BAKER
EARLIER TODAY HAS EXITED TO OUR SOUTHEAST. OVERALL PATTERN REMAINS
QUITE AMPLIFIED WITH A COLD TROF APPROACHING THE NORTH CENTRAL
CONUS AND A STRONG RIDGE OVER THE WESTERN STATES. COLDER CANADIAN
AIR IS BEGINNING TO SPILL INTO OUR EAST WITH AFTERNOON TEMPERATURE
DROPS NOTED AT BAKER AND MILES CITY. OUR WEST IS NEAR 60F WITH
MIXED W-NW WINDS...SO THERE EXISTS A NEAR 30 DEGREE TEMPERATURE
DIFFERENCE ACROSS OUR CWA THIS AFTERNOON. SFC HIGH BUILDING OUT OF
CANADA WILL ALLOW FOR A SHIFT TO EAST WINDS TO BACKDOOR ACROSS
MUCH OF OUR CWA TONIGHT.

THERE ARE SEVERAL ISSUES TO DEAL WITH OVER THE NEXT COUPLE OF DAYS
AS THE PREVIOUSLY STAGNANT WX PATTERN BREAKS DOWN AT LEAST
PARTIALLY. WE WILL TAP INTO A LARGE AREA OF LOW CLOUD TO OUR
NORTHEAST...AND COULD SEE SOME FOG ACROSS OUR EAST LATER TONIGHT.
LOW LEVELS MAY ALSO BECOME SATURATED ENOUGH TO SUPPORT DEVELOPMENT
OF FLURRIES OR LIGHT FREEZING DRIZZLE IN OUR FAR EAST. TEMPERATURE
PROFILES SHOW BOUNDARY LAYER TEMPS NEAR -10C AT BAKER SO PCPN TYPE
IS SOMEWHAT IN QUESTION. WILL KEEP MENTION OF BOTH FLURRIES AND
FREEZING DRIZZLE...ALONG WITH PATCHY FOG. SOME TRAVEL DIFFICULTIES
MAY RESULT FOR FOLKS IN OUR EAST LATE TONIGHT INTO FRIDAY MORNING.

LOOKING WEST...MOIST ISENTROPIC ASCENT OFF THE PACIFIC WILL BEGIN
TO OVERRUN THE BACKDOORING COLDER AIR LATE TONIGHT...GIVING US A
GOOD CHANCE OF LIGHT PCPN ALONG A EASTWARD PROPAGATING BAROCLINIC
ZONE FRIDAY AND FRIDAY NIGHT...IN THE FORM OF A RAIN/SNOW MIX.
COMBINATION OF ELEVATED WARMING EAST OF SFC TROF AND SOME MID
LEVEL DRYING OVER TIME COULD YIELD A MIX OF LIGHT SNOW AND LIGHT
FREEZING PCPN FOR OUR EASTERN PARTS FRIDAY NIGHT. PCPN WILL TAPER
OFF FROM WEST TO EAST FRIDAY NIGHT AS SFC TROF SHIFTS EAST AND
STRONGER/DRIER DOWNSLOPING PUSHES OFF THE FOOTHILLS.

FOR BILLINGS...EXPECT EAST WINDS TO DEVELOP TONIGHT AND PERSIST
THROUGH FRIDAY...RESULTING IN A MUCH COOLER DAY TOMORROW THAN WE
HAVE SEEN IN AWHILE. WITH TEMPS IN THE 30S TO LOWER 40S WE MAY
ALSO SEE SOME LIGHT SNOW OR RAIN FROM EARLY MORNING TO MID
AFTERNOON...THOUGH ADMITTEDLY THE BETTER PCPN CHANCES SHOULD BE
NORTH AND EAST OF US PER STRONGER MID LEVEL FORCING. BILLINGS WILL
SEE A RETURN OF DRIER/WARMER SW DOWNSLOPE WINDS FRIDAY NIGHT.

NEXT MORE UNSTABLE PACIFIC SHORTWAVE WILL BRING SCATTERED RAIN
SHOWERS WITH SOME MOUNTAIN AND FOOTHILL SNOW SHOWERS SATURDAY AND
SATURDAY NIGHT...WITH GREATEST PCPN CHANCES FOR OUR SOUTH. EXPECT
SOME BRIEF SNOW ACCUMULATION FOR THE HIGH TERRAIN. WE WILL ALSO
SEE A GUSTY MIXED W-NW WIND DEVELOP ON SATURDAY. TEMPS ON SATURDAY
SHOULD REMAIN ABOVE NORMAL WITH HIGHS MOSTLY IN THE 40S TO LOWER
50S. JKL

.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
MODELS HAVE BECOME LESS WINDY IN THE LONG TERM...BUT MORE
FAVORABLE FOR SOME UPSLOPE PRECIP. IN ADDITION TO THE SHORTWAVE
THAT STARTS MOVING THROUGH SATURDAY...THE GFS HAS ANOTHER
SHORTWAVE THAT FORMS RIGHT BEHIND THE WAVE AS IT IS DEPARTING.
THIS WILL KEEP THE PRECIP CHANCES GOING. TEMPERATURES WILL REMAIN
COOLER...BUT STILL WARMER THAN NORMAL. THIS WILL CREATE MOSTLY
RAIN IN THE LOWER ELEVATIONS. WITH THE MAIN RIDGE AXIS REMAINING
TO THE WEST...THE AREA WILL REMAIN IN NORTHWEST FLOW THAT IS
UNSETTLED THROUGH MUCH OF THE WEEK. HAVE KEPT SLIGHT CHANCES FOR
PRECIP THROUGH MUCH OF THE EXTENDED. TEMPERATURES WILL INCREASE
THROUGH THE WEEK TO BE SIMILAR TO TEMPERATURES WE HAVE SEEN THIS
WEEK. REIMER

&&

.AVIATION...
MVFR CONDITIONS HAVE MOVED INTO KMLS AND KBHK WITH LOW CLOUDS AND
THESE CONDITIONS ARE EXPECTED THE REST OF THE NIGHT. AREA OF FOG
AND A LIGHT SNOW AND LIGHT FREEZING DRIZZLE ARE POSSIBLE EAST OF
KBIL OVERNIGHT AS COLD AIR DEEPENS. MVFR CONDITIONS ARE POSSIBLE
AT KBIL LATE TONIGHT AND EARLY FRIDAY IN LOW CLOUDS AND THE CHANCE
OF LIGHT SNOW. WEST OF KBIL...MAINLY VFR CONDITIONS ARE EXPECTED
BUT A MIX OF SCATTERED RAIN AND SNOW SHOWERS COULD LEAD TO LOCAL
MVFR CONDITIONS OVERNIGHT. TWH

&&

.PRELIMINARY POINT TEMP/POPS...

    FRI     SAT     SUN     MON     TUE     WED     THU
-----------------------------------------------------------
BIL 033/043 035/053 035/051 036/058 040/060 037/060 036/057
    14/O    13/W    23/W    32/W    22/W    11/B    12/W
LVM 038/057 040/046 034/047 037/054 043/055 037/055 035/051
    33/R    04/W    35/W    33/W    22/W    11/N    23/W
HDN 030/045 029/055 031/052 032/058 037/060 031/061 032/058
    14/O    14/W    33/W    43/W    22/W    11/B    12/W
MLS 024/037 028/051 031/050 032/053 036/053 031/055 034/054
    12/S    54/W    21/B    22/W    22/W    11/B    11/E
4BQ 025/039 028/051 030/050 030/054 033/054 031/057 034/056
    12/O    43/W    32/W    23/W    22/W    11/B    11/E
BHK 019/030 020/043 029/046 028/048 033/048 028/049 031/050
    11/Z    54/W    31/B    12/W    22/W    11/B    11/E
SHR 029/046 029/051 029/047 030/053 034/055 030/057 031/053
    12/O    13/W    52/W    32/W    12/W    11/B    11/E

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS



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