Weather Service Report


547 
FXUS65 KBYZ 220320
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT 
820 PM MST SUN DEC 21 2014

.UPDATE...

SEVERAL CHANGES TO INHERITED FORECAST THIS EVENING...MAINLY
CENTERED AROUND EXPIRING ASSORTED HIGHLIGHTS FOR WESTERN ZONES.

THE WINDS ACROSS WESTERN ROUTES HAVE TAPERED OFF SIGNIFICANTLY
SINCE SUNSET...AND SHOULD NOT THREATEN WARNING AND ADVISORY
CRITERIA AGAIN OVERNIGHT OR MONDAY. HAVE CANCELLED ALL WIND
HIGHLIGHTS AND PARED WINDS BACK OVERNIGHT. BREEZY CONDITIONS WILL
CONTINUE THROUGH TOMORROW IN MOST AREAS...BUT WILL BE BELOW
HIGHLIGHT CRITERIA.

ADDITIONALLY...CANCELLED THE WINTER STORM WARNING FOR THE
BEARTOOTH/ABSAROKA MOUNTAINS. ALTHOUGH SNOW WILL CONTINUE THROUGH
THE NIGHT AND MUCH OF TOMORROW...ACCUMULATIONS WILL BE
SIGNIFICANTLY LIGHTER.

OTHERWISE CURRENT FORECAST APPEARS TO BE IN GOOD SHAPE. AAG

&&

.SHORT TERM...VALID FOR MON AND TUE...

DYNAMIC SHORTWAVE IN NW FLOW ALOFT CURRENTLY PUSHING THROUGH
SOUTHEAST MT. STRONG WINDS HAVE BEEN OCCURRING FOR SEVERAL HOURS
IN HARLOWTON AND JUST RECENTLY WE HAVE SEEN GUSTS TO 58-59 MPH
SURFACE AT BILLINGS AND COLUMBUS...WITH SOME ASSISTANCE FROM THE
LIGHT SHOWER ACTIVITY AROUND THE AREA. PEAK GUSTS COINCIDE PRETTY
WELL WITH RAP 800MB WINDS...AND AS TEMPS HAVE REACHED THE LOW 50S
THE BOUNDARY LAYER IS WELL-MIXED. RAP/GFS SHOW 800MB FLOW
INCREASING TO 55 KTS OVER THE NEXT FEW HOURS FROM BILLINGS TO
SHERIDAN...IN PATH OF VORT MAX AS SEEN ON WATER VAPOR IMAGERY.
GIVEN THE INGREDIENTS AND AN EXPECTATION OF A FEW HOURS OF STRONG
W-NW WINDS HAVE ISSUED A HIGH WIND WARNING THRU MIDNIGHT TO
INCLUDE COLUMBUS...BILLINGS...HARDIN...LODGE GRASS AND SHERIDAN.
ELSEWHERE WILL MAKE NO CHANGES TO WIND HIGHLIGHTS THOUGH WOULD
EXPECT A DECREASE LATER TONIGHT IN THESE AREAS AS WELL.
LIVINGSTON...BIG TIMBER AND NYE HAVE STAYED BELOW ADVISORY
CRITERIA FOR MUCH OF THE DAY BUT WITH STRONGER GUSTS NEARBY WILL
LET THE HIGHLIGHT RIDE A BIT LONGER.

HEAVIEST SNOW HAS ENDED OVER OUR SW MTNS AS MOISTURE PLUME HAS
BEEN PUSHED W-S OF OUR AREA...BUT UNSTABLE NW FLOW IS CONTINUING
TO PRODUCE SNOW SHOWERS WHICH ARE PROBABLY LOCALLY HEAVY. IN
ADDITION...THERE IS A SHORT-LIVED BULGE OF ISENTROPIC ASCENT
LATER TONIGHT INTO MONDAY MORNING AHEAD OF ANOTHER PIECE OF
ENERGY...AND THIS SHOULD ENHANCE THE SNOW SHOWERS ESPECIALLY FOR
NW ASPECTS. WILL LET THE WINTER STORM WARNING RIDE FOR THE
BEARTOOTH ABSAROKAS THRU NOON TOMORROW.

NEXT AREA OF CONCERN IS OUR FAR EAST AS TROWAL WRAPS SOUTHWARD
ACROSS FAR SOUTHEAST MT TOMORROW ON BACK SIDE OF UPPER LOW IN THE
DAKOTAS. LOOKS LIKE A 1-3 INCH SNOWFALL WHICH COMBINED WITH NW
WIND GUSTS OF 35-45 MPH WILL CAUSE SOME BLOWING SNOW AND POOR
TRAVEL CONDITIONS. HAVE ISSUED A WINTER WX ADVISORY TO COVER THIS
FOR FALLON AND CARTER COUNTIES. IMPACTS WILL ALSO BE FELT FURTHER
WEST TOWARD MILES CITY...BROADUS...LAME DEER AND SHERIDAN THOUGH
CURRENT INDICATIONS ARE THAT GREATEST SNOW ACCUMS WILL BE CLOSER
TO THE DAKOTAS BORDER. WIND GUSTS SHOULD EXCEED 50 MPH IN SHERIDAN
TOMORROW...WITH ENHANCEMENT ALONG THE EAST SLOPES OF THE BIGHORN
MOUNTAINS. PCPN IN OUR EAST SHOULD TAPER OFF BY EARLY TUESDAY AS
HEIGHTS BEGIN TO RISE FROM THE WEST.

PERIOD OF DRY WEATHER IS IN STORE TUESDAY AND TUESDAY NIGHT AS
RIDGE BUILDS IN FROM THE WEST. BACKED FLOW ALOFT ALONG WITH LEE
SIDE TROFFING AND COLD AIR IN THE PARK WILL BRING OUR NEXT PERIOD
OF STRONG SW WINDS FOR THE USUAL GAP AREAS.

TEMPS WILL TAKE A STEP DOWN THE NEXT TWO DAYS BUT WILL REMAIN A
LITTLE ABOVE NORMAL WITH HIGHS MOSTLY IN THE 30S TO LOWER 40S.
COOLEST TEMPS WILL BE FELT NEAR THE DAKOTAS BORDER.

JKL

.LONG TERM...VALID FOR WED...THU...FRI...SAT...SUN...

CONSISTENCY IN THE MODELS IS NOT OPTIMAL BUT STILL STRONG ENOUGH
TO START SUPPORTING A DEPICTION OF HOW THE WEATHER WILL UNFOLD
THROUGH THE CHRISTMAS HOLIDAY. WEDNESDAY WILL BE VERY WINDY ACROSS
A LARGE PORTION OF THE REGION AND MILD. WEDNESDAY NIGHT A COLD
FRONT MOVES INTO AFTER THE EVENING HOURS...SOMETIMES BETWEEN 10 PM
AND 4 AM. THIS BRINGS A SHIFT TO MUCH COLDER TEMPERATURES AND
SNOWFALL. THIS SOLUTION IS SUPPORTED BY A BLEND OF LATEST WRF AND
ECMWF AND GFS IS THE OUTLIER. FRONT IS FAST MOVING WITH SHORT
LIVED SNOWFALL CHANCES BUT UPPER LEVEL SUPPORT MOVES OVER THE
FRONTAL ZONE WHICH COULD ALLOW FOR A 2 TO 3 INCH SNOWFALL IN 8
HOURS. 

HAVE DRIED OUT WEDNESDAY DAY FORECAST A LITTLE BUT KEPT SNOWFALL
CHANCES FOR WEDNESDAY NIGHT AND CHRISTMAS DAY. FRIDAY IS A QUIETER
DAY WITH COOL NORTHWEST FLOW BUT IT IS MOSTLY DRIER WITH A CHANCE
OF MOUNTAIN SNOW. SATURDAY LOOKS RELATIVELY QUIET TOO BUT AN
ADDITIONAL ROUND OF GAP FLOW WINDS COULD BE SETTING UP LATER ON
SATURDAY NIGHT. 

MODELS PICKING UP ON A STRONGER ARCTIC INTRUSION NEXT WEEKEND BUT
NOT CONFIDENT IF ITS SUNDAY OR MONDAY. THIS LOOKS LIKE A MUCH
STRONGER PATTERN CHANGE THAN THE WEDNESDAY NIGHT SYSTEM. BORSUM 

&&

.AVIATION...

WINDY CONDITIONS WILL PERSIST INTO MONDAY WITH SOME OCCASIONAL
GUSTS BETWEEN 30 AND 40 KTS. SNOW WILL INCREASE ACROSS EASTERN
MONTANA WHICH WILL LIKELY RESULT IN AREAS OF IFR/LIFR CONDITIONS
IN LOWER CEILINGS AND VISIBILITIES IN SNOW FOR AREAS FROM KMLS
EASTWARD. OTHERWSIE...VFR CONDITIONS WILL PREVAIL. FRIEDERS

&&

.PRELIMINARY POINT TEMP/POPS...

    MON     TUE     WED     THU     FRI     SAT     SUN     
-----------------------------------------------------------
BIL 034/041 025/039 026/041 029/034 015/030 014/031 015/029
    22/W    20/N    02/W    66/S    31/B    11/B    22/S
LVM 031/037 016/034 023/041 028/036 012/029 012/032 018/032
    44/J    20/N    03/W    77/S    41/B    12/S    22/S
HDN 031/040 022/037 019/040 025/033 011/029 010/030 010/028
    33/J    30/B    02/W    66/S    31/B    11/B    22/S
MLS 029/034 022/035 020/040 025/031 013/027 014/029 009/026
    47/J    31/B    13/W    43/S    21/E    12/S    22/S
4BQ 031/034 024/034 017/042 026/035 013/028 012/030 010/028
    47/J    62/J    11/E    45/S    21/E    11/B    22/S
BHK 027/030 021/030 015/039 022/030 010/023 012/025 007/022
    78/J    62/J    12/W    33/S    21/B    12/S    22/S
SHR 030/037 022/035 018/042 025/033 012/030 011/034 013/030
    44/W    41/B    02/W    66/S    31/B    11/B    22/S

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 5
      AM MST TUESDAY FOR ZONES 33-37.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS

Return to Home page


Western Regional Climate Center, wrcc@dri.edu