Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 231725
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
1025 AM MST Thu Feb 23 2017

.UPDATE...

No changes to highlites with this update. After looking at 12z
models increased high temperatures a few degrees for this
afternoon. Also adjusted pops with categorical values in the
upslope favored foothills trending down to slight chance over
northeast zones. Increase in low level moisture advection this
afternoon combined with transit of upper low into eastern Wyoming
will help increase snow shower activity across the plains this
afternoon into the evening hours. Some of these snow showers could
be briefly heavy at times. Again, roads will be mainly wet or
slushy this afternoon but will freeze up this evening. Chambers

&&

.SHORT TERM...valid for Tdy and Fri...

Water vapor imagery shows slow moving upper low near the NV/ID/UT
triple point, with strong diffluence producing precipitation from
southeast ID thru central WY where strong mid level baroclinicity
exists. Colder tops are spreading into southeast MT, but the
synoptically driven precipitation remains well to our south as of
10Z this morning. Upslope snow showers in our cwa have become much
lighter since last evening.

Main trend among recent models are to keep stronger forcing
further to our south, though weak isentropic ascent will persist
thru today and into tonight as the low tracks thru WY to western
NE. Currently light snow showers are a result of fairly shallow
moisture that is extending into the dendritic layer, and upslope
flow of course. Pcpn will likely remain light until moisture
deepens in association with the upper low...a bit later this
morning.

Snow will intensify across our southern upslope areas and east
side of the Crazies today into tonight, and will make no changes
to winter storm warnings in these areas. Given trend toward weaker
forcing and shallower moisture, have reduced forecast snow
amounts north of foothill areas, and have cancelled the winter wx
advisory for Musselshell County where synoptic and orographic
forcing will be lacking. For Billings, it will snow occasionally
today and tonight but accumulations will be less than previously
thought, up to an inch or two by Friday morning, and mainly on the
grass. Wind/blowing snow will not be a factor with this system.
Will keep advisories going as roads have no doubt iced up even in
areas without much new snowfall. Drive carefully for the morning
commute.

Precipitation will taper thru the day on Friday, but with some
light snow showers persisting across our west/south in response to
lingering upper divergent flow and a still reasonably moist
dendritic layer. Another shortwave dropping out of western Canada
will keep the chance of snow showers going Friday night.

Temperatures will be seasonably cool the next couple days with
highs mostly mid 20s to mid 30s.

JKL

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

Little changes made to the extended portion of the forecast
period.

On Saturday morning, a frontal system will slide into central
Montana bringing a round of snow showers with minor accumulations
mainly to areas from Sheridan to Billings to Roundup and westward.
By late afternoon, snow will push a bit further east onto the
Plains before weakening by Sunday morning.

This cold frontal passage will keep temperatures generally below
normal with highs in the 30s and lows generally in the teens to
low 20s. Another reinforcing low arrives on Monday, but models
suggest the bulk of the energy will remain well to the southwest
of our area, so significant accumulating snow does not look
likely at this time. Given the northwest flow aloft and presence
of the low, there should be periods of scattered snow showers in
the foothills and mountains. Therefore, have slightly increased
the snow chances across the western foothills and areas around
Livingston through mid-week. Expect below normal temperatures
through the period with temperatures trending toward normal by
late next week. Walsh

&&

.AVIATION...

Low CIGS and/or reduced VIS in snow will continue to cause
IFR/LIFR conditions at LVM and SHR through the late morning
hours. Otherwise, MVFR to IFR conditions persist across the rest
of the region under low CIGS. Mainly MVFR/IFR CIGS are expected by
early afternoon, with locally heavy snow showers lowering VIS to
IFR/LIFR at times. AAG

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Fri     Sat     Sun     Mon     Tue     Wed
-------------------------------------------------------
BIL 034 022/033 018/032 018/033 016/032 018/032 019/038
    6/J 64/S    34/J    21/B    32/J    22/J    21/B
LVM 031 016/028 013/028 011/029 012/031 015/029 016/035
    +/S 85/S    44/J    22/J    44/J    43/J    22/J
HDN 035 021/035 016/034 016/034 014/034 017/033 017/040
    5/J 53/S    24/J    21/B    22/J    22/J    21/B
MLS 037 022/036 020/035 020/037 018/035 019/034 018/040
    2/J 21/B    22/J    21/B    22/J    22/J    21/B
4BQ 034 019/035 017/036 018/036 015/036 019/034 017/040
    5/J 41/E    23/W    21/B    22/J    12/J    21/B
BHK 033 018/033 017/032 017/033 015/033 016/031 015/035
    2/J 10/B    12/J    21/B    22/J    22/J    21/B
SHR 033 017/030 011/030 008/031 009/029 012/031 013/036
    9/S 85/S    33/J    21/U    11/B    12/J    21/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Weather Advisory in effect until noon MST Friday FOR
      ZONES 28-34-38>41-58-63-65.
     Winter Storm Warning in effect until noon MST Friday FOR
      ZONES 56-66>68.
WY...Winter Weather Advisory in effect until noon MST Friday FOR
      ZONE 98.
     Winter Storm Warning in effect until noon MST Friday FOR ZONE
      99.

&&

$$
weather.gov/billings



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