Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 041640
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
940 AM MST THU FEB 4 2016

.UPDATE...

PREVIOUS FORECAST LOOKS TO BE IN GOOD SHAPE SO I AM NOT
ANTICIPATING ANY UPDATES THIS MORNING. WINDS ARE STILL GUSTING TO
60 MPH IN THE LIVINGSTON AREA. AN UPPER LEVEL DISTURBANCE AND
PACIFIC FRONT WILL MOVE ACROSS THE AREA TODAY. THIS WILL BRING IN
SOME COLD AIR ADVECTION ALOFT...AS WELL AS SHIFT THE LEE- SIDE
TROUGH EAST OF THE AREA. AS A RESULT...THE ADVISORY WINDS ARE
EXPECTED TO DECREASE BY LATE THIS MORNING/EARLY AFTERNOON FOR THE
LIVINGSTON AREA. THE PACIFIC FRONT WILL USHER IN GUSTY WESTERLY
WINDS ACROSS THE ENTIRE FORECAST AREA SO IT WILL BE A BREEZY TO
WINDY DAY. SNOW SHOWERS WILL BE CONFINED TO THE MOUNTAINS AND
FOOTHILLS WITH A SLIGHT RAIN/SNOW SHOWER CHANCE EAST OF BILLINGS.
AREAS IN BETWEEN SHOULD REMAIN DRY DUE TO A STRONG DOWNSLOPE FLOW.
WILL CONTINUE THE WIND ADVISORY FOR THE LIVINGSTON AND FOOTHILLS
AREAS UNTIL NOON. HOOLEY

&&

.SHORT TERM...VALID FOR TDY AND FRI...

WIND IS THE MAIN CONCERN THROUGH THE SHORT TERM PERIOD...AND THE
LONG TERM FOR THAT MATTER...AND THE FORESEEABLE FUTURE. ANYONE
LOOKING FOR A SNOW EVENT SHOULD STOP READING NOW.

WATER VAPOR IMAGERY SHOWS UPPER RIDGE OVER CENTRAL MT WITH AN
APPROACHING PACIFIC TROF EXTENDING FROM WA TO NV. LEE SIDE TROF
WITH A PRESSURE DIFFERENCE OF 16MB FROM IDA-LWT HAS RESULTED IN
INCREASED GAP FLOW AT LIVINGSTON AND NYE...AND JUST RECENTLY THE
LVM ASOS GUSTED TO 58 MPH. WIND ADVISORY IS ALREADY IN EFFECT TIL
NOON FOR THESE AREAS AND WILL MAKE NO CHANGES. ONSET OF COLD
ADVECTION LATER THIS MORNING WILL END THE STABLE GAP FLOW AND
MIXED WESTERLY WINDS WILL COMMENCE. SHOULD SEE GUSTS NEAR 50 MPH
AT BIG TIMBER AND HARLOWTON LATER TODAY...AND GENERALLY BREEZY
CONDITIONS ACROSS THE LOWER ELEVATIONS.

EXPECT SNOW SHOWERS AND A FEW INCHES OF ACCUMULATION OVER THE
BEARTOOTH/ABSAROKA AND CRAZY MOUNTAINS TODAY...PER BRIEF PERIOD OF
ASCENT AND STEEPENING MID LEVEL LAPSE RATES. STRONG DOWNSLOPING
WILL KEEP MOST OF OUR WESTERN LOWER ELEVATIONS DRY TODAY...BUT
SHOULD SEE SOME LIGHT RAIN/SNOW SHOWERS OVER OUR EAST LATER TODAY
AND TONIGHT AS SHORTWAVE PASSES AND FLOW TURNS NORTHWESTERLY.
ISOLATED TO LOW SCATTERED POPS ACROSS OUR EAST SHOULD COVER THIS.

NEXT PERIOD OF UPPER LEVEL RIDGING WILL BRING DRY CONDITIONS
FRIDAY INTO FRIDAY NIGHT...AND OF COURSE THE DEVELOPING LEE SIDE
TROF WILL ALLOW FOR INCREASED GAP FLOW ONCE AGAIN. THIS NEXT
PERIOD OF WIND WILL INVOLVE FASTER MID LEVEL FLOW AND A TIGHTER
SFC GRADIENT...WITH PLENTY OF STABILITY...SO EXPECT WINDS TO STEP
UP ACCORDINGLY. WILL PUSH GUSTS FOR LIVINGSTON AND NYE UP TO THE
60-70 MPH RANGE FOR FRIDAY NIGHT. STRONG WINDS FOR BIG TIMBER AND
HARLOWTON SHOULD HOLD OFF TIL SATURDAY WHEN PRESSURE FALLS SLIDE
EAST.

AS FOR TEMPS...WARMING TREND WILL CONTINUE THE NEXT TWO DAYS AS WE
REMAIN DOMINATED BY PACIFIC FLOW. SHOULD SEE GOOD MIXING AND TEMPS
INTO THE UPPER 30S AND LOWER 40S TODAY...THEN LOWER TO MID 40S
FRIDAY WITH STRONGER RIDGING ALOFT AND CONTINUED LOWER ELEVATION
DOWNSLOPE FLOW.

JKL

.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...

A WINDY AND WARM EXTENDED FORECAST IS STILL ON TAP FOR THE FORECAST
AREA SAT THROUGH THU. WHILE THE ENSEMBLES SHOWED A SIMILAR
SYNOPTIC PATTERN FOR THE PERIOD...THE TEMPERATURE SPREADS BETWEEN
MODELS WERE IN THE MEDIUM TO HIGH CATEGORY. THE REASON FOR THIS
WAS THAT BEGINNING SUN NIGHT...THE FORECAST AREA WILL BE ON THE E
SIDE OF A STRONG RIDGE UNDER NW FLOW AS AN OMEGA BLOCK SETS UP
FROM THE EASTERN PACIFIC THROUGH THE EASTERN U.S.. THE EASTERN
SIDE OF THE RIDGE OPENS UP THE POSSIBILITY OF BACKDOOR FRONTS
SLIDING INTO THE AREA WHICH ADDS UNCERTAINTY TO THE FORECAST.

THAT BEING SAID...NOTED SMALL DIFFERENCES BETWEEN THE
DETERMINISTIC MODELS BEGINNING ON SAT AS A PACIFIC SHORTWAVE MOVES
THROUGH THE REGION. THE GFS TAKES THE WAVE AND IT/S ENERGY ACROSS
THE AREA...WHILE THE ECMWF FOCUSES THE ENERGY N OF THE MT/CANADIAN
BORDER. THE RESULT IS THE GFS BRINGS MORE PRECIPITATION/MOISTURE
INTO THE AREA THAN THE ECMWF. IN ADDITION...DOWNSLOPE FLOW WILL BE
FIGHTING THE LIFT OVER THE AREA. THUS REDUCED POPS A LITTLE USING
THE CONSALL GUIDANCE. THE ECMWF WAS SHOWING A WARMER AIRMASS THAN
THE GFS SO WENT WITH THE SUPERBLEND GUIDANCE. KEPT SOME POPS OVER
THE AREA SAT NIGHT...THEN WENT MOSTLY DRY ON SUN WITH THE RIDGE
BUILDING INTO THE AREA. SUN WILL BE A BIT COOLER BEHIND THE WAVE.

STRONG RIDGING AND A DRY AIRMASS WILL THEN PREVAIL OVER THE REGION
MON THROUGH WED. TUE AND WED LOOKED QUITE WARM WITH HIGHS IN THE
50S. NOTED THE ECMWF HAD A SHORTWAVE MOVING OVER THE RIDGE ON THU
WHILE THE GFS DID NOT HAVE THIS FEATURE. AS A RESULT OF THE
WAVE...THE ECMWF TRIES TO PUSH A BACKDOOR FRONT INTO THE REGION.
GIVEN THE LIKELIHOOD THAT THIS SCENARIO WILL UNDERGO CHANGES SINCE
IT IS DAY 8...STUCK WITH A DRY FORECAST AND SUPERBLEND GUIDANCE
FOR TEMPERATURES FOR NOW.

THE PATTERN SUPPORTED WINDY CONDITIONS ACROSS THE AREA FOR THE
WEEKEND...WITH POSSIBLE HIGHLIGHTS NEEDED W OF KBIL...THEN WINDY
CONDITIONS WILL PERSIST W OF KBIL THROUGH MOST OF THE PERIOD. ARTHUR

&&

.AVIATION...

ISOLATED TO SCATTERED SNOW SHOWERS WILL BRING LOCALIZED
MVFR CONDITIONS TO AREAS AROUND KLVM AND N OF KBIL THIS MORNING.
LOCALIZED MVFR CONDITIONS WILL OCCUR AROUND KLVM AND E OF KBIL THIS
AFTERNOON AND EVENING DUE TO ISOLATED RAIN AND SNOW SHOWERS.
EXPECT WIDESPREAD OBSCURATIONS OVER THE CRAZYS...BEARTOOTHS AND
ABSAROKAS TODAY...WITH AREAS OF OBSCURATION OVER THE NE BIGHORNS.
ISOLATED SNOW SHOWERS WILL CONTINUE E AND S OF KBIL LATE
TONIGHT. GUSTY W TO SW SURFACE WINDS WILL AFFECT AREAS W OF KBIL
THROUGH THIS EVENING. EXPECT GUSTS OF 45 TO 50 KT OVER KLVM.
ARTHUR/DOBBS

&&

.PRELIMINARY POINT TEMP/POPS...

    TDY FRI     SAT     SUN     MON     TUE     WED
-------------------------------------------------------
BIL 042 028/045 033/048 030/043 029/049 034/055 034/053
    1/N 10/N    02/W    21/N    11/N    00/N    00/N
LVM 038 024/040 033/042 026/040 028/046 034/049 033/049
    3/W 31/N    13/W    21/N    11/N    00/N    11/N
HDN 042 025/045 026/048 026/044 022/046 028/051 028/051
    1/N 20/B    02/W    21/N    11/E    10/U    01/U
MLS 041 025/045 029/050 029/042 024/042 029/048 030/047
    2/W 20/U    02/W    31/N    01/E    11/B    01/U
4BQ 040 025/043 024/048 026/041 022/042 026/049 028/048
    2/W 21/B    03/W    31/N    01/B    11/B    01/U
BHK 038 024/041 025/048 027/038 021/037 025/044 026/043
    2/W 31/B    02/W    31/N    01/N    11/B    01/U
SHR 039 022/041 022/047 024/039 021/045 027/051 027/050
    1/E 20/B    02/W    21/N    11/B    10/U    00/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT UNTIL NOON MST TODAY FOR ZONES 65-66.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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