Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 212212

Area Forecast Discussion
National Weather Service Billings MT
312 PM MST Wed Feb 21 2018

.SHORT TERM...valid for Thu and Fri...

No significant changes to the going forecast for this package.
Weak short wave energy continues to drop into the cyclonic long
wave pattern across the northern Rockies. This will deepen the
upper trof into the Great Basin in the short term. This will mean
some light snow at times in the Absaroka/Beartooths and slowly
moderating temperatures across the eastern plains. We do see some
warm air advection (850-700mb) over the eastern zones as early as
tonight/tomorrow, but not quite convinced it will be able to mix
out the colder air in the river valleys yet. So generally kept
forecast numbers under guidance in the eastern zones.

We do anticipate some lee-side surface troughing by Friday night.
This will induce increasing wind for the western foothills and
the usual gap locations of Nye and Livingston. BT

.LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...

Several minor changes for the extended forecast period, but
primarily for coordination.

A piece of energy is dragged along the jet into the region late
Saturday, with some colder air to mitigate warm up, and shut down
gusty winds across the west. This will also bring at least a
slight chance of snow into the foothills western zones overnight.
There appears to be at least a short period of upslope frow into
the foothills, which would indicate a period of increased
snowfall. Raised pops slightly in foothills to reflect increased
potential. Good moisture advection, and some upper dynamics
associated with the jet will support a slight chance of snow
Sunday into Monday, especially west of Billings. None of the
precipitation chances look impressive or impactful at this point.

Temperatures trend colder through the beginning of the workweek,
as a deep storm system takes shape over the western third of the
CONUS. Have generally kept inherited climo type pops in place, as
system still has a lot of uncertainty with it. Large scale
details appears to be shifting significantly from run to run.
Additionally, have held on to below average temps, as appears
colder air should infiltrate the area regardless of where best
energy moves. This system will continue to demand attention,
especially since it fits a heavy snow pattern for our area should
it develop and move just right. That said it is still a long ways
out, with any number of impactful changes possible over time.


Expect mainly VFR conditions to continue through the period with
passing mid and high clouds. Snow showers and mountain
obscurations will remain possible over the western mountains much
of the period. Expect breezy conditions to redevelop in and around
KLVM late this evening and overnight, with southwest winds gusting
around 25 to 35 kts.  AAG



    Thu     Fri     Sat     Sun     Mon     Tue     Wed
BIL 904/020 903/022 007/030 010/030 014/031 011/025 007/023
    00/U    00/U    01/B    22/J    22/S    22/S    33/S
LVM 002/025 000/026 013/030 019/032 018/032 014/030 010/028
    01/B    10/B    13/S    43/J    35/S    32/S    43/S
HDN 912/019 905/020 001/029 008/029 011/031 008/025 006/023
    00/U    10/B    11/B    22/J    22/S    22/S    33/S
MLS 912/010 906/015 901/024 006/023 008/026 006/021 005/020
    00/U    00/B    01/B    11/B    22/E    11/B    33/S
4BQ 906/018 903/018 001/026 008/026 010/031 010/026 008/023
    00/U    00/B    01/B    11/B    12/B    22/S    44/S
BHK 909/014 904/015 001/024 006/024 006/028 007/022 005/021
    00/U    00/B    00/B    11/B    12/B    11/B    23/S
SHR 909/017 905/021 000/029 008/029 011/031 010/027 008/025
    00/U    01/B    01/B    22/J    12/B    33/S    33/S




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