Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 120842
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
242 AM MDT SAT APR 12 2014

.SHORT TERM...VALID FOR TDY AND SUN...

EARLY SPRING STORM STILL EXPECTED TO IMPACT PORTIONS OF OUR
FORECAST AREA TODAY INTO SUNDAY. A ZONAL FLOW IS CURRENTLY MOVING
ACROSS OUR STATE EARLY THIS MORNING BUT THIS WILL QUICKLY GIVE WAY
TO A NORTHWEST/NORTH FLOW ALOFT AS A COLD FRONT WILL SWEEP ACROSS
THE FORECAST AREA BY MID MORNING. THIS WILL USHER IN GUSTY
NORTHWEST TO NORTH WINDS WHICH WILL THEN BECOME NORTHEAST THIS
AFTERNOON. A 500MB AND 700MB UPPER LOW WILL BECOME POSITIONED OVER
EASTERN IDAHO BY EARLY THIS EVENING. THIS COMBINED WITH A
NORTHEAST SURFACE FLOW WILL ALLOW FOR A DEEP UPSLOPE FLOW ACROSS
THE BIG HORN AND BEARTOOTH/ABSAROKA MOUNTAINS AND ADJACENT
FOOTHILLS TONIGHT INTO SUNDAY MORNING. LOWER LEVELS ARE EXPECTED
TO QUICKLY MOISTEN BY LATE THIS MORNING RESULTING IN THE
DEVELOPMENT OF SHOWER ACTIVITY ACROSS OUR FAR WESTERN AREAS WITH A
MORE GENERAL RAIN DEVELOPING AND SPREADING EAST TO BILLINGS AND
SOUTHEAST TOWARD SHERIDAN THIS AFTERNOON.

TEMPERATURES WILL START OFF MILD THIS MORNING IN THE 40S TO LOWER
50S BEFORE SLOWING FALLING BY THIS AFTERNOON...SO DAYTIME HIGHS
WILL ACTUALLY BE REACHED THIS MORNING. MODELS DO NOT BRING 850MB
0C TEMPERATURES INTO THE AREA UNTIL THIS EVENING BUT BELIEVE RAIN
WILL MIX WITH SNOW THIS AFTERNOON FOR THE FOOTHILLS LOCATIONS WITH
THE RAIN BECOMING ALL SNOW BY EARLY EVENING FOR THE FOOTHILLS
AREAS AND BY LATE EVENING FOR THE LOWER ELEVATIONS ADJACENT TO THE
FOOTHILLS. LIQUID AMOUNTS CONTINUE TO LOOK ON THE ORDER OF
0.25-1.00" WITH THIS SYSTEM. GIVEN SNOW RATIOS IN THE 12-15:1
RATIO...SIGNIFICANT SNOW AMOUNTS WILL BE LIKELY FOR THE MOUNTAINS
AND FOOTHILLS. AS A RESULT...HAVE UPGRADED THE WINTER STORM WATCH
FOR THE MOUNTAINS AND FOOTHILLS TO A WARNING STARTING THIS
AFTERNOON THROUGH SUNDAY MORNING. WILL ALSO ISSUE A WINTER WEATHER
ADVISORY FOR SNOW FOR THE AREAS ADJACENT TO THE FOOTHILLS FROM
SHERIDAN TO LIVINGSTON FOR THIS EVENING THROUGH SUNDAY MORNING.

THE UPPER LOWS AND DYNAMICS QUICKLY SHIFT SOUTH DURING THE DAY
SUNDAY AS DRIER AIR IN THE MID LEVELS MOVES OVER THE FORECAST
AREA. AS A RESULT...THE SNOW WILL BE ENDING FROM NORTH TO SOUTH
LATE SUNDAY MORNING INTO SUNDAY AFTERNOON. A COOL NORTHERLY FLOW
ALONG WITH MOSTLY CLOUDY SKIES WILL KEEP TEMPERATURES WELL BELOW
NORMAL SUNDAY WITH HIGHS ONLY IN THE UPPER 30S TO LOWER 40S AT
BEST. HOOLEY

.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...

GFS SOLUTIONS FOR FIRST HALF OF THE WEEK HAVE TRENDED CLOSER TO
THE ECMWF SOLUTIONS. THEREFORE...WILL USE THE ECMWF AS PRIMARY
GO-TO MODEL FOR THE EXTENDED PERIODS.

TRENDS FROM PREVIOUS PACKAGE STILL LOOK GOOD WITH 500MB HEIGHTS
REBOUNDING MONDAY...BUT ANOTHER WEATHER SYSTEM MOVES ACROSS THE
REGION LATE TUESDAY THROUGH WEDNESDAY. WE CONTINUE TO LOWER
FORECAST TEMPERATURES FOR WEDNESDAY AS A DECENT CANADIAN FRONT
AGAIN SLIPS INTO THE REGION. EASTERLY LOW LEVEL FLOW AND 500MB
HEIGHT FALLS AT MIDWEEK WILL LEAD TO ANOTHER PRECIPITATION
EVENT...MAINLY IN UPSLOPE AREAS OF THE MOUNTAINS/FOOTHILLS AND
NEARBY LOWER ELEVATIONS.

IT APPEARS ZONAL FLOW WITH SOME WEAK WAVES ORIGINATING FROM THE
PACIFIC WILL KEEP OUR WEATHER UNSETTLED FOR THE LATTER PART OF
THE WEEK. HOWEVER...TEMPERATURES WILL LIKELY BE SEASONAL WITHOUT
ANY SIGNIFICANT COOLDOWNS ANTICIPATED. BT
&&

.AVIATION...

MAINLY VFR CONDITIONS THIS MORNING WILL GRADUALLY TURN MVFR BY
AFTERNOON WEST OF A KBIL TO KSHR LINE. WINDS WILL TURN NORTHERLY
AND INCREASE BY 18Z. MVFR TO IFR CONDITIONS ARE ANTICIPATED OVER
THE REGIONAL MOUNTAINS AND NEARBY FOOTHILLS BY LATE AFTERNOON.
MOUNTAINS WILL BECOME OBSCURED AS HEAVY SNOW DEVELOPS IN THE HIGH
COUNTRY AFTER 20Z. BT
&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SUN     MON     TUE     WED     THU     FRI
-------------------------------------------------------
BIL 049 027/039 024/055 035/061 035/041 028/052 035/059
    8/R 84/O    10/B    02/W    44/W    22/W    23/W
LVM 048 025/039 021/055 033/059 034/048 028/052 033/055
    +/R +6/S    10/N    03/W    44/W    22/W    33/W
HDN 050 029/040 024/056 031/064 033/041 028/054 032/061
    7/R 84/O    10/B    02/W    44/W    12/W    23/W
MLS 051 026/040 023/054 030/059 031/037 026/051 030/059
    2/R 32/O    10/B    01/B    34/W    12/W    22/W
4BQ 051 027/039 023/054 030/062 032/039 026/051 029/059
    4/R 42/O    10/B    02/W    34/W    12/W    12/W
BHK 050 024/037 020/048 026/053 026/032 022/045 025/054
    2/R 22/O    10/B    00/B    33/W    12/W    22/W
SHR 050 026/037 020/052 028/061 032/043 028/050 031/058
    8/R +7/S    20/U    02/W    33/W    32/W    12/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
      NOON MDT SUNDAY FOR ZONES 34-38>41-65.
     WINTER STORM WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO
      NOON MDT SUNDAY FOR ZONES 56-66-67.
WY...WINTER WEATHER ADVISORY IN EFFECT FROM 6 PM THIS EVENING TO
      NOON MDT SUNDAY FOR ZONE 99.
     WINTER STORM WARNING IN EFFECT FROM 3 PM THIS AFTERNOON TO
      NOON MDT SUNDAY FOR ZONE 98.

&&

$$
WEATHER.GOV/BILLINGS



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