Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 120943
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
243 AM MST Tue Dec 12 2017

.SHORT TERM...valid for Tdy and Wed...

A more active weather pattern is in store for the short-term.
Shortwave, seen on water vapor moving onto the central BC coast,
will approach MT today and push a cold front through N MT by 00Z.
It will be warm, dry and windy ahead of the front, with RH`s in
the upper teens and 20s over many areas. Winds will increase in
the foothills locations this morning, and gusty winds will
overspread the area through the day. The combination of the
orientation and strength of the surface pressure gradient, a
persistent low-level inversion, and drainage through the valleys
in the western zones aided by pressure falls, will create very
windy conditions in the gap flow areas, as well as Big Timber and
Harlowton. Local guidance supports the very windy conditions as
well. Thus will issue a Wind Advisory for KLVM and the Beartooth
Foothills thru this evening, and a High Wind Warning for Big
Timber to Harlowton. Will continue the Rangeland Fire Danger
Statement issued earlier, and add Powder River and Big Horn
Counties to the statement, as RH`s will be low in these areas and
windy conditions will arrive in the afternoon. Will also mention
fire concerns in the Wind Advisory/Warnings.

The cold front will move S through the area through 06Z tonight,
ushering weak pressure rises into the area. Winds aloft will
remain strong, so expect breezy conditions through the night. The
previously mentioned shortwave will move into the Dakotas
overnight. On Wednesday, a N-S oriented jet will move S into the
region, bringing some jet divergence to the area through Wed.
night. Weak shortwave energy will accompany the jet, as well as
some moisture. Continued the western mountain PoPs for Wed., and
the PoPs over SE MT and Sheridan County for late Wed. night.
Wednesday will be cooler than today, but still above normal for
this time of year. Arthur

.LONG TERM...valid for Thu...Fri...Sat...Sun...Mon...

After a warm, breezy and dry Thursday the strong upper ridge that
has dominated the forecast breaks down bringing cooler and
unsettled conditions for the rest of the extended. Best chances
for precipitation will be Friday night into Saturday, though
slight chance pops do exist Sunday through the middle of next
week. Despite the pattern change and cooler temperatures, will
continue to have to deal with gusty winds for the foreseeable
future as the jet stream orients itself over the area through the
extended. Western foothills winds look strong on Friday and again
Sunday into Monday for possible wind advisory periods around
Livingston and Nye. These gusty winds will downslope into the
plains holding down precipitation chances despite a good feed of
Pacific moisture, and keeping temperatures above seasonal normals
for the most part.

Looking closer to Christmas travel time, models continue to
advertise a change to colder and snowier conditions developing by
the middle to later part of next week. Most significantly the
latest (00z) GFS drops an arctic intrusion into the area for the
22nd (next Thursday)as a strong ridge builds in the Gulf of Alaska
dislodging polar air southward into our area. 850mb temperatures
drop to colder than -20C for Billings which would equate to a high
around 0F on the 22nd. The ECMWF has that airmass a bit further
northeast at 240hrs with the Canadian in between the GFS/EC. This
solution is way out there in time with a lot of time to change,
but for the busy travel week before Christmas things are certainly
beginning to look significantly colder/snowier than what we have
been experiencing. Chambers
&&

.AVIATION...

VFR conditions across the region today. West to southwest winds
will gust 25 to 40kts at times most locations, with higher gusts
expected in the western foothills from KLVM to K6S0 and K3HT.
Chambers

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 056 034/048 030/047 032/053 030/041 025/045 030/044
    0/N 00/N    10/U    00/B    44/W    11/B    22/J
LVM 052 031/044 028/043 031/046 029/037 025/040 031/041
    0/N 02/W    10/U    00/N    54/W    11/N    22/W
HDN 059 029/049 027/045 027/054 029/042 023/046 029/046
    0/N 00/U    10/U    00/B    43/W    11/B    22/J
MLS 055 030/045 028/039 025/051 028/040 023/044 028/042
    0/U 00/B    21/B    00/B    33/W    11/B    22/J
4BQ 058 032/046 029/040 025/053 028/040 023/045 028/043
    0/N 00/N    32/J    00/B    33/W    11/B    22/J
BHK 052 027/040 025/035 021/046 025/037 020/041 025/039
    0/U 00/N    33/J    01/B    22/J    11/B    11/B
SHR 062 030/047 026/043 025/054 026/039 020/045 026/045
    0/U 00/U    11/N    00/B    34/W    21/B    12/J

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Warning in effect until 9 PM MST this evening FOR
      ZONES 28-41.
     Wind Advisory in effect until 9 PM MST this evening FOR ZONES
      65-66.
WY...None.

&&

$$
weather.gov/billings



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