Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 202217
AFDBYZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
317 PM MST THU NOV 20 2014

.SHORT TERM...VALID FOR FRI AND SAT...

THE HIGH CLOUDS HAVE STARTED TO MOVE ACROSS THE WESTERN HALF OF
THE AREA. THESE WILL CONTINUE TO EXPAND EAST ACROSS THE AREA AS
THE RIDGE PULLS OUT AND A WEAK PACIFIC SHORT WAVE MOVES THROUGH.
STILL NOT EXPECTING MUCH PRECIP WITH THE SYSTEM...MAYBE SOME LIGHT
SNOW IN THE MOUNTAINS.

THE MAIN FOCUS IN THE SHORT TERM IS THE WIND EVENT FOR LIVINGSTON
AND NYE AS THE NEXT SYSTEM MOVES THROUGH TOMORROW NIGHT AND
SATURDAY. WINDS CONTINUE TO LOOK STRONG AS THE FRONT COMES THROUGH
FOR LIVINGSTON AND NYE. THE PRESSURE GRADIENT IS SETUP FOR A GOOD
GAP WIND EVENT. THUS...HAVE INCREASED WINDS A BIT...BASED ON
GUIDANCE...AND AM LEANING TOWARDS A HIGHER END ADVISORY EVENT WITH
GUSTS 65 TO 70 MPH POSSIBLE. GUIDANCE ALSO HAS WINDS INCREASING
FROM BIG TIMBER TO HARLOWTON BEHIND THE FRONT SATURDAY. THESE
WINDS WILL NOT BE AS STRONG AS AT LIVINGSTON OR NYE...BUT GUSTS
COULD BE UP TO 50 MPH.

OTHERWISE THE TEMPERATURES CONTINUE TO LOOK A LITTLE MORE
SEASONAL...AND HAVE CONTINUE TO HAVE 40S IN FOR HIGHS AND MID TO
UPPER 20S. REIMER

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

COOLER AND UNSETTLED WEATHER WITH SOME CHANCE OF SNOW SHOWERS WILL
BE THE OPERATIVE MODE BETWEEN SUNDAY AND TUESDAY WITH A NORTHWEST-
ERLY FLOW ALOFT ACROSS THE REGION. WE ARE RATHER CONFIDENT IN THAT
SCENARIO AND WE BELIEVE THE PROBABILITY OF ANY HIGH-IMPACT WEATHER
IN THAT TIME FRAME IS RELATIVELY LOW.

HOWEVER...FORECAST CONFIDENCE DROPS OFF DRAMATICALLY BY THE MIDDLE
OF NEXT WEEK...AND IT/S BELOW-AVERAGE EVEN RELATIVE TO A NORMALLY-
MODEST CONFIDENCE LEVEL FOR FIVE TO SEVEN DAY FORECASTS. THE ECMWF
HAS STAYED THE COURSE IN ADVERTISING A COLD AND SNOWY PATTERN FROM
TUESDAY NIGHT INTO WEDNESDAY...WITH LINGERING ARCTIC CHILL ALL THE
WAY INTO THANKSGIVING. THE GFS HAD BEEN A LESS-EXTREME...BUT STILL
COOL SOLUTION WITH SOME OPPORTUNITY FOR RAIN OR SNOW...BUT ITS NEW
12 UTC RUN MADE A DRAMATIC SWITCH IN SHOWING A WELL-FORMED MIDDLE-
AND UPPER-LEVEL RIDGE OVER THE ENTIRE REGION DURING THAT SAME TIME
FRAME. THE DIFFERENCE IN STATISTICAL FORECAST GUIDANCE IS ABOUT AS
LARGE AS IT CAN GET...WITH THE 12 UTC GFS-BASED MOS /MEX/ HAVING A
HIGH OF 59 F AT BILLINGS ON THANKSGIVING WHILE THE 00 UTC ECMWF ON
THE SAME DAY CALLS FOR A HIGH OF 24 F. OUR OFFICIAL FORECAST TAKES
THE RESPONSIBLE ROUTE OF CALLING FOR A MIDDLE GROUND OF BOTH IDEAS
FOR THE TUESDAY NIGHT THROUGH THANKSGIVING PERIOD FOR NOW. THERE/S
CERTAINLY SOME SUPPORT FOR THE MORE EXTREME ECMWF IDEA BEING WRONG
THOUGH BECAUSE 1/ IT REMAINS COLDER THAN THE 00 UTC ECMWF ENSEMBLE
MEAN...AND 2/ THE ARCTIC OSCILLATION IS EXPECTED TO MOVE WELL INTO
THE POSITIVE RANGE FOR THE LATTER HALF OF THE MONTH...AND WE OFTEN
NEED THAT TO BE NEGATIVE FOR A DEEP OR LONG-LIVED ARCTIC OUTBREAK.
INTERESTINGLY...THE NEW 13 KM /PARALLEL/ GFS IS VERY WARM LIKE THE
OPERATIONAL VERSION...AND IT ACTUALLY WENT OVER TO A WARM SOLUTION
AS EARLY AS LAST NIGHT. SCHULTZ

&&

.AVIATION...

VFR CONDITIONS WILL PREVAIL TONIGHT AND FRIDAY THOUGH THERE MAY BE
LOCAL MOUNTAIN OBSCURATIONS WITH A FEW SNOW SHOWERS. WINDS WILL BE
SOMEWHAT GUSTY IN AND AROUND THE FOOTHILLS LIKE AT KLVM. SOME LOW-
LEVEL WIND SHEAR IS ALSO LIKELY AT KMLS TONIGHT AND FRIDAY MORNING
AS WESTERLY WINDS INCREASE TO 30 KT WITHIN 2000 FT AGL. SCHULTZ

&&

.PRELIMINARY POINT TEMP/POPS...

    FRI     SAT     SUN     MON     TUE     WED     THU
-----------------------------------------------------------
BIL 028/046 029/048 030/041 025/038 023/038 022/034 014/032
    00/B    12/W    22/W    22/J    23/J    44/W    31/B
LVM 028/044 030/045 024/035 021/033 019/034 022/032 014/029
    00/N    14/W    22/J    32/J    34/J    54/W    31/N
HDN 022/046 022/049 026/041 020/038 019/038 018/034 010/031
    00/B    02/W    22/W    22/J    23/J    44/J    31/B
MLS 021/043 021/041 025/034 015/030 014/034 015/027 007/028
    00/B    02/W    32/J    22/J    22/J    23/J    21/B
4BQ 020/045 021/044 026/036 017/031 015/034 017/030 010/027
    00/B    02/W    22/J    22/J    23/J    33/J    31/B
BHK 020/042 020/040 024/030 012/023 012/030 012/022 004/024
    00/B    02/W    23/J    22/J    22/J    22/J    21/B
SHR 023/045 021/045 022/037 017/034 015/035 017/033 011/030
    00/U    03/W    32/J    22/J    23/J    44/J    32/J

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.

&&

$$
WEATHER.GOV/BILLINGS


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