Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 170314
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
814 PM MST Tue Jan 16 2018

.UPDATE...
Temperatures which began falling just before sunset in some areas
have steadied out as falling surface pressure over Alberta is
increasing southerly low level flow for most areas. A few very
sheltered valleys may fall a few more degrees but in general most
areas are close to overnight minimum forecasts and do not expect
much more cooling. No updates. borsum

&&

.SHORT TERM...valid for Wed and Thu...

Shallow arctic air making for a difficult temp forecast tonight
and possibly even tomorrow. Most of the western and central areas
have warmed up nicely today, but cold air in eastern valleys has
been more stubborn. However, all progs agree that low level flow
will turn more westerly tonight. So temps in eastern valleys might
slowly rise overnight at some locations rather than cool off.
Western foothills will benefit from weak lee-side troughing and
remain breezy and relatively mild overnight. Many locations should
be much milder tonight.

For Wednesday, short wave moves across Canadian border and helps
scour out remaining cold air in east. Should see nice warming
over the entire CWA. Even milder temps expected on Thursday as
short wave ridge and prefrontal warming take place. Winds will
slowly increase in the foothills. By Wednesday evening, pressure
gradient tightens across foothills. Local tools and guidance
suggest advisory level winds are likely. Future shifts will
monitor a bit longer, but advisory is certainly supported from
what we currently see...from Wednesday evening through Thursday
afternoon, and possibly into Thursday evening. At that point,
Pacific weather system pushes through our region.

Our main concern with this frontal system Thursday night is the
slight chance of some ice pellets./freezing precipitation falling.
Best chance of this is from Billings eastward to the Miles City
vicinity in those river valley locations. The bulk of
precipitation looks to come after the 700mb cold front moves
through early Friday morning, but any lighter precipitation may be
mixed prior to that Thursday night. We will monitor this closely
as even through chance is slight, it would have a large impact on
travel conditions. BT


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

Little in the way of changes for the extended forecast period,
with models in reasonably good agreement on overall progressive
pattern.

Pacific SW flow will persist through Friday evening, and combine
with jet divergence to the area as a strong Pacific jet sinks SE
through the region. Fairly good moisture appears to be in place,
with PWATS around a half an inch. So inherited pops look pretty
good. Currently continuing with rain/snow mix much of Friday
afternoon/evening, but there is some concern for freezing rain as
cold air undercuts warm/moist airmass. Will continue to watch
closely, but FZRA potential does not look as favorable as in
previous runs.

Precip will clear the region by Saturday morning, and upper
ridging will build back into the region Saturday night/Sunday
morning. Sunday will see strong and gusty winds develop in and
around Livingston, Nye, and Big Timber, as a strong surface high
moves west to east across Yellowstone National Park. Southeast
winds, with gusts around 60mph are possible Sunday
afternoon/evening. A shortwave will cross the region to flatten
ridge on Sunday night/Monday morning, and give surface high a kick
eastward. This will also bring reinforcing shot of cool air, but
limited chance of precip as atmosphere is relatively dry at this
point.

Upper level flow remains flat through remainder of period,
bringing some downslope low and warming temps, until Tuesday, when
another wave is progged into the region, but timing is an issue
with this wave.

Temperatures will generally be in the 30s through the end of this
week. Friday looks to be the warmest day, with upper 30s in most
locations. Monday and Tuesday will be cooler behind reinforcing
shortwave Monday and cold front Tuesday, with highs in 20s to end
the period. AAG
&&

.AVIATION...


Breezy conditions will continue in and around KLVM, with gusts
around 30kts possible overnight. Winds vc KLVM will vary from W to
NW overnight, becoming SW Wednesday morning. LLWS is possible over
southeast MT late tonight, including at KMLS. VFR conditions are
expected to prevail across the area through the period. STP

&&

.PRELIMINARY POINT TEMP/POPS...

    Wed     Thu     Fri     Sat     Sun     Mon     Tue
-----------------------------------------------------------
BIL 022/041 029/048 029/038 019/032 015/032 014/025 010/025
    00/U    00/N    55/O    31/B    11/N    22/S    22/S
LVM 026/043 033/049 029/037 015/033 015/034 019/034 016/033
    00/N    01/N    86/O    31/N    22/S    33/S    33/S
HDN 010/039 020/045 024/038 016/034 012/031 010/025 008/026
    00/U    00/B    35/O    31/B    11/B    22/S    22/S
MLS 009/034 020/040 027/037 017/030 011/029 007/018 007/016
    00/U    00/B    33/O    21/B    11/B    12/S    22/S
4BQ 012/040 021/045 027/038 019/034 014/033 011/026 010/023
    00/U    00/B    14/O    21/B    11/B    12/S    22/S
BHK 010/038 020/044 027/040 019/034 011/031 011/021 008/016
    00/U    00/B    13/O    21/B    11/B    12/S    22/S
SHR 015/042 023/048 028/037 018/031 014/033 015/028 012/027
    00/U    00/B    15/O    32/S    11/B    12/S    22/S

&&

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

&&

$$
weather.gov/billings


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