Weather Service Report


122 
FXUS65 KBYZ 240339
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT 
839 PM MST Fri Feb 23 2018

.UPDATE...
Weak/split upper trof remains over eastern MT, but mid level winds
are increasing in central MT ahead of strong northwesterly jet 
along the Pacific coast. Lee side pressure gradients have 
increased, but we have recently seen a brief pressure rise in 
response to aforementioned weak trof, with another period of 
pressure falls expected later tonight. It is later tonight when we
will see winds at Livingston, Big Timber and Nye (and to a lesser
extent Harlowton) increase. Orientation of gradient will become 
more favorable over time, but do not see enough mid level flow to 
get gusts up to advisory strength. That being said, still 
expecting 50 mph gusts later tonight into Saturday morning. Winds 
will decrease but remain gusty as mid levels become more unstable 
tomorrow afternoon. All of that being said, it will otherwise be a
quiet night of weather, with increasing snow showers over the 
western mountains as the upstream Pacific trof moves inland. Have 
adjusted temperatures down a bit more in eastern valleys per 
current observations...already near or below zero at Sheridan, 
Forsyth, Hysham and Miles City. It will be a warmer night than the
past several nights though, warmest in our west of course with 
the increased wind along the foothills. JKL

&&

.SHORT TERM...valid for Sat and Sun...

Overall, quiet weather will continue into the weekend with no 
significant snow expected. A series of upper lows and troughs will
move onto the Pacific northwest coast, then dig southeast into 
the four corners area during the next several days, and this is 
where the bulk of any precipitation will be situated. A few weak 
disturbances will move across our forecast area through the 
weekend bringing a slight snow shower chance with the best chance 
coming Sunday and Sunday night, mainly for the Beartooth/Absaroka 
Mountains and adjacent foothills. 

The main impact in the short term will be the return for strong 
gusty winds for the Upper Yellowstone and Stillwater Valleys 
tonight into Saturday morning. Lee-side troughing will set up 
along with tighter pressure gradients. Wind and model guidance 
have decreased slightly for the possibility for advisory winds for
the Livingston to Nye area during this time. Confidence is high 
for 50 mph gusts but somewhat lower for gusts of 60 mph. As of 
now, gusts around 55 mph looke likely with a few higher gusts. As 
a result, we will hold off on issuing any wind advisories for 
those areas at this time. These strong gusty winds will cause 
areas of blowing and drifting snow from Billings and areas 
westward, especially for areas prone to drifting. A much better 
chance for advisory winds for these areas arrives Sunday and 
Sunday night. Confidence is much higher for this period and an 
advisory will most likely be needed later this weekend. 
Temperatures for the weekend will moderate slightly to around or 
slightly above freezing. Hooley

.LONG TERM...valid for Mon...Tue...Wed...Thu...Fri...

Overall, the forecast is not tremendously active with a couple of
splitting systems moving through the area. This will translate 
into below seasonal temperatures, with general troughiness still 
in place, and low chance of snowfall. The mountains and the west 
will have the best chance of getting snow through the week, with 
the plains remaining mostly dry.

The first splitting system to move through Monday and Monday 
night, with the vast majority of the energy getting buried to the 
south into southern California. A weak northern trough will 
provide enough ascent for low PoPs, but as stated above, these 
PoPs will be mainly confined to the mountains and the west.

The next system swings into the northern Rockies late in the 
week. There was inconsistency with this system on previous runs of
the ECMWF and GFS, but the models were coming closer to agreement
now. The trough cuts a low off over southeast Montana, which 
would put the best chance of significant snowfall over northern 
Montana. This will need to be monitored closely, as the GFS was 
cutting the low off further south and lining up closer with the 
ECMWF. Still looks to far north to be a significant weather maker 
for southern Montana and northern Wyoming at this time. TWH

&&

.AVIATION...

Surface high pressure departing the region will allow for 
increasing winds along the foothills and adjacent plains overnight
into Saturday morning. Expect wind gusts to 45 kts at KLVM and 
other favored locations. Blowing snow is possible with minor 
reductions to visibility as far east as KBIL. Isolated snow 
showers, with occasional obscurations, are expected over the 
mountains. TWH/RMS

&&

.PRELIMINARY POINT TEMP/POPS...

    Sat     Sun     Mon     Tue     Wed     Thu     Fri     
-----------------------------------------------------------
BIL 013/033 015/036 019/033 010/034 014/036 014/035 014/034
    00/N    11/Q    22/J    11/U    11/B    11/B    11/B
LVM 015/029 019/035 020/032 009/035 015/037 016/038 018/038
    22/J    42/Q    33/J    21/N    22/J    22/J    22/J
HDN 000/031 008/035 016/033 007/032 010/033 010/033 010/034
    00/B    11/B    12/J    11/B    11/B    11/B    11/B
MLS 903/022 010/032 016/029 007/028 009/029 008/028 009/029
    00/B    11/B    11/B    10/U    11/B    11/B    11/B
4BQ 000/024 008/032 015/032 008/030 011/032 011/032 012/032
    00/B    11/B    11/B    11/B    11/B    11/B    10/B
BHK 001/021 010/032 016/030 007/028 010/029 008/029 010/029
    00/B    11/B    11/B    00/B    01/B    00/B    00/B
SHR 901/032 009/036 015/032 008/033 009/035 011/035 012/037
    00/B    21/B    12/J    21/B    11/B    11/B    11/B

&&

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

&&

$$
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Western Regional Climate Center, wrcc@dri.edu