Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 281622
AFDBYZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BILLINGS MT
922 AM MST FRI NOV 28 2014

.UPDATE...
SOME MOUNTAIN WAVE ACTIVITY WAS OVER THE FORECAST AREA THIS
MORNING PER OBSERVATIONS AT TIPI VILLAGE IN RED LODGE AND GUSTY
WINDS AT KSHR. GFS MODEL CROSS-SECTIONS SHOWED THIS ACTIVITY WILL
BE LESS LIKELY THIS AFTERNOON...AND NOTED THAT WINDS WERE STARTING
TO DECREASE AT THESE LOCATIONS. WILL BE MONITORING NEW MODEL DATA
FOR MORE POSSIBLE MOUNTAIN WAVE ACTIVITY TONIGHT.

KLVM SITES WERE HITTING SUSTAINED ADVISORY WIND CRITERIA EARLIER
THIS MORNING. WILL CONTINUE THE ADVISORY FOR KLVM AND NYE THROUGH
SAT MORNING AND CHECK NEW MODEL DATA FOR A POSSIBLE WARNING AT
THOSE LOCATIONS.

TEMPERATURES WERE ALREADY IN THE 40S AND 50S ACROSS THE AREA AT
16Z. EXPECT A RISE OF SEVERAL MORE DEGREES DUE TO DOWNSLOPE FLOW
AND A LITTLE SUNSHINE...BUT THE HIGH CLOUD COVER WILL INHIBIT MUCH
MORE WARMING. RAISED TEMPERATURES A COUPLE OF DEGREES W OF KBIL
AND OVER KSHR.

WARM ADVECTION COMBINED WITH LIFT FROM A COUPLED JET AND WEAK
VORTICITY WILL CREATE SOME MORE MOUNTAIN SHOWERS AND SHOWERS E OF
KBIL...AWAY FROM DOWNSLOPE AREAS THIS AFTERNOON...SO HAVE ADDED
LOW POPS OVER THE E AFTER 18Z.

QUICK GLANCE AT NEW WRF/GFS SHOWED PRECIPITATION MOVING EVEN
FASTER INTO THE AREA ON SAT...REACHING NORTHERN AREAS BY 18Z WHEN
THE COLD AIR HAS ALREADY SURGED THROUGH THE AREA. PLAN ON ISSUING
HIGHLIGHTS FOR THE UPCOMING SYSTEM THIS AFTERNOON. ARTHUR

&&

.SHORT TERM...VALID FOR TDY AND SAT...

ARCTIC FRONT IS COMING EARLY SATURDAY BUT WE HAVE SOME WIND
ISSUES TO CONTEND WITH FIRST. WINDS HAVE HIT ADVISORY CRITERIA
ALREADY AT THE USUAL SPOTS OF LIVINGSTON...BIG TIMBER AND NYE.
WILL MAKE NO CHANGES TO EXISTING HIGHLIGHTS IN THESE AREAS.
CURRENT SFC TEMPS ARE QUITE MILD AND IN THE LOW 50S ALONG THE
FOOTHILLS...AND AS A RESULT OF THE WELL-MIXED BOUNDARY LAYER WE
ARE SEEING STRONG WINDS AT OTHER LOCATIONS. TIMBERCREST RAWS ABOVE
RED LODGE GUSTED TO 58 MPH AND FISHTAIL RAWS RECENTLY HIT 61 MPH.
SHERIDAN HAS ALSO FLIRTED WITH MOUNTAIN WAVE GUSTS AROUND 40 MPH
IN THE LEE OF THE BIG HORN MOUNTAINS. NAM/GFS/RUC EACH SHOWED A
MTN TOP WIND MAX OCCURRING IN THE 06-12Z TIME FRAME AND THESE
GUSTS ARE CONSISTENT WITH THIS. AFTER SOME DECREASE ANTICIPATED
THIS MORNING WE ARE EXPECTING MID LEVEL FLOW TO INCREASE LATER
TODAY AND ESPECIALLY TONIGHT. THOUGH THERE ARE CONCERNS ABOUT LOW
LEVEL STABILITY...MODELS ALSO SUGGEST STRONGER DOWNWARD MOTION IN
THE LEE OF THE MTNS...AND A PREFRONTAL TIME PERIOD IS
CLIMATOLOGICALLY IDEAL FOR MTN WAVES. WITH THIS IN MIND HAVE UPPED
EXPECTED WINDS AT PLACES LIKE ROSCOE...RED LODGE...DAYTON AND
SHERIDAN TODAY AND TONIGHT WITH GUSTS OF 40-50 MPH EXPECTED. WILL
NEED TO KEEP WATCH OF THIS.

LIVINGSTON 3 AM TEMP OF 53 DEGREES IS ONLY 4 DEGREES OFF FROM A
DAILY RECORD MAX TODAY. DAILY RECORDS FOR NOVEMBER 28TH ARE WEAK
AND WE COULD SEE THEM REACHED AT BOTH LIVINGSTON AND BILLINGS.

IT WILL BE VERY MILD THROUGH MOST OF TONIGHT BUT THIS WILL COME TO
A SCREECHING HALT WITH THE ARRIVAL OF AN ARCTIC FRONT EARLY
SATURDAY MORNING. TEMPS WILL FALL DRASTICALLY THROUGH THE DAY
TOMORROW. EXPECT TEMPS TO FALL INTO THE SINGLE DIGITS AND TEENS BY
AFTERNOON...THEN TO NEAR OR BELOW ZERO AT NIGHT AS CORE OF SFC
HIGH PUSHES IN WITH 850MB TEMPS ON THE ORDER OF -20C. TEMPS IN
NORTHERN ALBERTA AND BC ARE CURRENTLY BELOW ZERO. AS FOR PCPN...
SNOW WILL DEVELOP AS UPPER TROF SLIDES FROM BC TOWARD THE PAC NW
AND NORTHERN ROCKIES...PARTIALLY PHASING WITH ENERGY OFF THE
PACIFIC COAST BEFORE WEAKENING AND PUSHING EAST QUICKLY SUNDAY.
GREATEST FORCING WILL BE SATURDAY AFTERNOON THROUGH THE NIGHT AND
BASED ON MODEL/ENSEMBLE QPF WE SHOULD SEE 0.10-0.20 INCHES OF
WATER WHICH WOULD YIELD GENERAL ACCUMS OF 2-4 INCHES OF SNOW WITH
GOOD SNOW RATIOS ANTICIPATED DURING PEAK FORCING. UPSLOPE
ENHANCEMENT WILL BE BRIEF BUT COULD SEE LOCALLY HIGHER AMTS ALONG
THE FOOTHILLS. PCPN SHOULD BEGIN TO TAPER OFF FROM NORTH TO SOUTH
LATE SATURDAY NIGHT.

JKL

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

SUNDAY LOOKS TO BE THE COLDEST DAY OF THE EXTENDED FORECAST
PERIOD AND THERE IS GOOD MODEL CONSISTENCY ON THAT. 850MB
TEMPERATURES OF -20C ON THE GFS AND -24C ON THE ECMWF SWING INTO
SOUTHERN MONTANA SUNDAY MORNING. SOME WEAK WARM AIR ADVECTION WILL
TAKE PLACE DURING THE AFTERNOON...BUT GIVEN THERE SHOULD BE A
LITTLE FRESH SNOW COVER ON THE GROUND FROM SATURDAY NIGHTS SNOW
EVENT...HIGHS WILL STAY WELL BELOW SEASONAL AVERAGES AND NOT MUCH
ABOVE 10 DEGREES.

MONDAY WILL BE QUITE A BIT WARMER WITH ZONAL FLOW. HIGHS SHOULD
BE ABLE TO REACH INTO THE LOWER TO MID 30S MOST PLACES. A CHUNK OF
ENERGY COMING OFF THE ALEUTIAN ISLANDS WILL SPLIT AND SLIDE ACROSS
MONTANA MONDAY NIGHT AND EARLY TUESDAY. THIS WILL BRING SOME
ASCENT FOR A CHANCE OF SNOW SHOWERS AND PULL DOWN A WEAK COLD
FRONT TO KEEP THE WARM UP AT BAY.

ONCE WE GET PASSED TUESDAY...NOT MUCH GOING ON FOR THE REST OF
THE WEEK AS WEAK WESTERLY FLOW ENSUES. TEMPERATURES WILL BE AT
SEASONAL LEVELS. DOWNSLOPE WILL NOT BE OVERLY STRONG...SO WILL
KEEP TEMPERATURES IN CHECK. OVERALL....NOT SEEING ANY WEATHER
EVENT TYPE OF ISSUES THROUGH NEXT WEEKEND...AS THE PATTERN IS
ADVERTISING QUIET WEATHER. TWH
&&

.AVIATION...

STRONG WEST TO SOUTHWEST WINDS WILL CONTINUE ALONG THE WESTERN
FOOTHILLS WITH SOME GUSTS TO 50KTS AT LIVINGSTON AND 40KTS AROUND
RED LODGE. WINDS ALONG THE FOOTHILLS WILL REMAIN STRONG THROUGH
TONIGHT. WINDS WILL NOT BE NEARLY AS STRONG OVER THE PLAINS BUT
SOME GUSTS TO 30KTS ARE ANTICIPATED AT BILLINGS. THE MOUNTAINS
WILL BE OCCASIONALLY OBSCURED WITH A FEW SNOW SHOWERS. A FEW
ISOLATED RAIN SHOWERS ARE ALSO POSSIBLE FROM KMLS TO KBHK TODAY
AND COULD BRING MVFR CONDITIONS. VFR CONDITIONS WILL PREVAIL AT
ALL OTHER FLIGHT TERMINALS. TWH/RICHMOND


&&

.PRELIMINARY POINT TEMP/POPS...

    TDY SAT     SUN     MON     TUE     WED     THU
-------------------------------------------------------
BIL 055 024/026 903/011 003/031 020/035 018/039 021/042
    0/N 06/S    92/S    01/B    22/J    11/B    21/B
LVM 059 035/036 902/014 006/033 024/037 020/039 026/043
    2/W 38/O    92/S    01/B    22/J    12/J    22/W
HDN 055 022/026 901/011 000/032 016/036 014/039 019/043
    0/E 05/S    82/S    01/B    22/J    11/B    21/B
MLS 049 017/019 904/009 901/027 015/028 011/034 015/037
    2/W 26/S    61/B    00/U    22/J    11/B    11/B
4BQ 054 026/031 000/011 901/032 016/035 014/040 019/042
    2/W 03/S    62/S    01/U    12/J    12/J    21/B
BHK 048 020/022 903/007 903/026 013/026 010/030 015/035
    2/W 04/S    51/B    01/U    12/J    11/B    11/B
SHR 061 029/039 002/011 000/034 019/037 017/041 021/044
    0/E 02/S    94/S    00/B    22/J    12/J    21/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WIND ADVISORY IN EFFECT UNTIL NOON MST SATURDAY FOR ZONES
      41-65-66.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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