Area Forecast Discussion
Issued by NWS Billings, MT

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273
FXUS65 KBYZ 252112
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
312 PM MDT MON APR 25 2016

.SHORT TERM...VALID FOR TUE AND WED...

TOUGH PATTERN OVER THE REGION FOR OUR MODELS TO HANDLE. ONE UPPER
LOW MOVING INTO MINNESOTA AND ANOTHER OVER THE GREAT BASIN.
PRECIPITATION HAS BEEN STREAMING INTO NORTHERN MONTANA TODAY
ALONG THE DEFORMATION AXIS. MOST OF THIS HAS REMAINED NORTH OF OUR
CWA. SO NOT A GREAT DEAL OF FORCING FOR US TO DEAL WITH AT THIS
TIME. THE MOST IMPORTANT QUESTION IS HOW FAR SOUTH THE UPPER
TROUGH OVER THE GREAT BASIN WILL TRACK AS IT MOVES THROUGH THE
CENTRAL ROCKIES OVER THE NEXT 24-48 HRS...AS THIS WILL DETERMINE
ITS OVERALL IMPACT ON OUR FORECAST AREA. THE GFS HAS THE 500MB
TROUGH POSITION OVER CENTRAL NEBRASKA BY WEDNESDAY MORNING...THUS
SPREADING A GOOD DEAL OF MOISTURE INTO OUR EASTERN ZONES. THE
ECMWF IS A LITTLE FURTHER SOUTH AND EAST SO KEEPS DEEPER MOISTURE
FROM EXTENDING VERY FAR WEST. AT THE SAME TIME...THE ATMOSPHERE
GETS STRETCHED OUT ALOFT AS UPPER LOW HAS TO PUSH THROUGH BLOCK TO
THE EASTERN CONUS. THIS RESULTS IN ANOTHER DEFORMATION ZONE BY
WEDNESDAY AFTERNOON WHICH PROGS SUGGEST WILL SET UP FROM SE
MONTANA TO NORTH CENTRAL MONTANA. SEVERAL WAVES UP PRECIPITATION
WORK FROM EAST TO WEST ALONG THIS AXIS WEDNESDAY INTO WEDNESDAY
NIGHT. MODELS ARE NOT CONSISTENT ON TIMING THESE WAVES...BUT
WEDNESDAY/WEDNESDAY NIGHT CERTAINLY LOOKS LIKE A RATHER DAMP
PERIOD. HAVE RAISED POPS FOR MANY LOCATIONS...WITH SOME
CATEGORICAL FOR EASTERN ZONES.

ALTHOUGH ENSEMBLES DO HAVE WIDE SPREADS...WE DO FEEL THE OVERALL
TRACK OF UPPER LOW THROUGH SOUTHERN WYOMING WILL BE FAVORABLE FOR
SOME MODERATE TO HEAVY WET SNOW OVER EAST FACING SLOPES OF THE
BIGHORNS. WILL ISSUE A WINTER WEATHER ADVISORY FOR NORTHERN
BIGHORNS WITH 4 TO 8 INCHES EXPECTED. THIS WILL BE VALID FROM
MIDNIGHT TONIGHT THROUGH 6 AM WEDNESDAY. ADDITIONAL PERIODS OF
SNOW ARE CERTAINLY POSSIBLE WEDNESDAY...SO THIS MAY NEED TO BE
EXTENDED OR ADJUSTED...BUT SEEMS TO BE A BREAK EARLY MORNING
WEDNESDAY.

HIGHER HILLS IN SE MONTANA MAY ALSO SEE A COUPLE OF INCHES
TUESDAY THROUGH WEDNESDAY NIGHT...BUT WE HAVE SOME TIME TO ANALYZE
FURTHER RUNS BEFORE ANY IMPACTS OCCUR. 850MB TEMPS DO LOOK PRETTY
COOL SO ROADS MAY SEE SOME SLUSH AND SLICK CONDITIONS AT SOME
POINT. BT

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

DID NOT MAKE MANY CHANGES TO THE FORECAST EXCEPT TO INCREASE
TEMPERATURES AT THE BEGINNING OF NEXT WEEK. THE LARGE PART OF THE
EXTENDED WILL BE COOL AND DAMP AS A MEAN TROUGH WILL BE IN PLACE
ACROSS THE WESTERN UNITED STATES.

THE EXTENDED STARTS WITH AN AREA OF LOW PRESSURE WEAKENING IN THE
DAKOTAS WEDNESDAY NIGHT INTO THURSDAY MORNING. WEAK EASTERLY FLOW
ALOFT WILL SEND RESIDUAL MOISTURE TOWARDS MONTANA GIVING MOST OF
THE AREA A CHANCE FOR SOME RAIN AND PERHAPS LIGHT SNOW IN THE
HIGHER ELEVATION AND HILLS ON THURSDAY. FURTHER TO OUR SOUTH...AN
UPPER LEVEL LOW WILL MOVE THROUGH THIS MEAN TROUGH AND AMPLIFY IT
ON FRIDAY. LOOKS LIKE MUCH OF THE ENERGY WILL STAY SOUTH OF THE
AREA...ESPECIALLY SEEING A WEAK RIDGE AXIS MOVE INTO THE
NORTHWESTERN US. CAN NOT RULE OUT A FEW SHOWERS IN SOUTHEASTERN
MONTANA AND NORTHERN WYOMING BUT MOST OF THE ENERGY SHOULD STAY
SOUTH. WITH CLOUDY CONDITIONS AND WEAK FLOW ALOFT EXPECTED FOR
OUR AREA.

UNCERTAINTY CREEPS INTO THE EXTENDED ON SATURDAY AS ANOTHER
SHORTWAVE ENTERS THE MEAN TROUGH. MODELS DIFFER IN THE HANDLING OF
THE TROUGH AS THIS SHORTWAVE INTERACTS WITH IT. AS OF NOW IT LOOKS
LIKE MUCH OF THE ACTIVE WEATHER WILL STAY SOUTH. SO IT IS LIKELY
THAT WARMER TEMPERATURES WILL RETURN LATE IN THE WEEKEND INTO
NEXT MONDAY. DOBBS
&&

.AVIATION...


MVFR/IFR CIGS WILL REMAIN IN PLACE OVER THE REGION THROUGH
TUESDAY MORNING. VCSH IS POSSIBLE AT ALL TERMINALS EXCEPT KBIL
FROM 00-09Z. LOCAL AREAS COULD SEE LIFR CONDITIONS AT
TIMES...MOSTLY BETWEEN 09-15Z. AFTER 18Z CIGS COULD LIFT SLIGHTLY
BUT MVFR CONDITIONS WILL LIKELY STICK AROUND. MOUNTAIN
OBSCURATIONS WILL BE A PROBLEM THROUGH THE TAF. DOBBS
&&

.PRELIMINARY POINT TEMP/POPS...

    TUE     WED     THU     FRI     SAT     SUN     MON
-----------------------------------------------------------
BIL 035/047 036/048 036/047 035/055 038/058 040/058 039/062
    23/O    44/O    54/W    33/W    23/W    33/W    22/W
LVM 035/050 033/052 034/049 032/055 035/058 036/058 035/062
    64/O    34/O    34/W    33/W    34/W    33/W    22/W
HDN 034/046 034/049 034/048 033/056 035/059 036/058 036/063
    35/O    55/O    55/W    33/W    23/W    32/W    22/W
MLS 034/047 035/047 033/048 033/055 038/058 039/058 038/063
    35/O    67/R    65/W    22/W    23/W    22/W    22/W
4BQ 033/044 034/044 032/046 030/054 035/056 037/056 036/061
    28/O    68/O    65/W    22/W    33/W    33/W    22/W
BHK 030/044 033/044 030/045 029/051 034/055 036/057 035/060
    37/O    68/O    84/W    21/E    23/W    33/W    21/B
SHR 034/043 032/046 032/047 032/054 033/056 034/055 034/059
    47/O    65/O    44/W    33/W    24/W    33/W    22/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 6
      AM MDT WEDNESDAY FOR ZONE 98.

&&

$$
WEATHER.GOV/BILLINGS



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