Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 161624
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
924 AM MST Mon Jan 16 2017

.UPDATE...
No updates this morning. Upper ridge was sliding into the
northern Rockies for a sunny day. Weak gradients today will limit
mixing and therefore the warm up will not be dramatic, especially
with deep snow cover. Highs will be very difficult with cold air
still trapped in valleys and limited mixing should not totally
scour it out. On the other hand, warm air is definitely moving in
aloft and should it mix to the surface, would lead to 40s
everywhere. Will let the temperature forecast ride. Gradients will
increase tonight as energy swings across southwest Canada. This
will get winds cranking over the Upper Yellowstone and Upper
Stillwater valleys. All things handled well in going package. TWH

&&

.SHORT TERM...valid for Tdy and Tue...

Very few changes were made to the short term forecast as weather
impacts remain minimal through Tuesday. Models continue to reamin
in good agreement for the next couple of days. High pressure
ridging along with rising heights will build across the forecast
area today allowing for sunny skies and warming temperatures.

However, by late tonight into Tuesday, the ridge gets flattened
somewhat as lee-side troughing develops due to low pressure
developing across southern Canada and high pressure over southeast
Idaho. As a result, pressure gradients will tighten across the
Upper Yellowstone and Upper Stillwater Valleys. This pattern will
continue well into Wednesday as well. Local wind guidance shows
advisory wind criteria likely being met late tonight into
Wednesday evening. As a result, we have issued a wind advisory for
the Beartooth/Absaroka Foothills areas from Livingston to Nye
starting late tonight through Wednesday night.

Sunny skies will prevail today with partly to mostly sunny skies
on Tuesday with dry conditions prevailing. Temperatures continue
to be tricky across the forecast area with wide variations over
small distances due to varying elevations and areas that have
mixing winds. Temperatures today will be similar to yesterday with
warmer readings expected Tuesday, but we still continue to
undercut model guidance by several degrees. Hooley

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

Warm conditions with windy conditions will continue Wednesday,
and in fact, this appears to be the warmest day of the week with
850mb temperatures of +10c to +12c. This should translate to 40s
everywhere and 50s along the foothills and in areas not sheltered.
Expect advisory level gusts at Livingston and Nye to continue
into Wednesday night before decreasing Thursday in response to a
more amplified Pacific trof moving into the intermountain west,
resulting in weaker downslope gradients. Thursday will again be
mild but likely cooler than Wednesday as 850mb temps begin to
cool, along with the weaker downsloping. Will be interesting to
see how much lower elevation snow we can melt through the middle
of the week. Will need to monitor rivers and streams for any ice
jam concerns, especially in our west as nighttime lows should stay
above freezing along the foothills.

Models have trended a bit more favorable for a period of showers
Thursday night into Friday, in response to passage of mid level
baroclinic zone underneath divergence in RRQ of southerly 100+ kt
H3 jet. Have raised pops, especially Thursday night in our west
and central parts where forcing looks greatest. Precipitation type
is not obvious, but favors a mix of rain/snow showers with a
little accumulation possible along the foothills as 850mb temps
cool toward +1C or +2C, with a better chance of a few inches of
accumulation over the high terrain of course. Cannot rule out
pockets of freezing rain depending on if any cold air remains
trapped in the lower valleys. Precipitation should generally taper
off Friday as jet departs and southerly split of trof pushes
through the central plains.

Weak flow aloft with below normal heights and general troffing in
store for next weekend, with jet energy well to our south. This is
a picture of poor confidence as far as precipitation chances go,
so will leave near climo pops (slight chance) across the cwa.
Temperatures will gradually cool each day from Friday through
Sunday as model consensus is for 850mb temps to fall to or below
0C. Models have actually trended a bit warmer with this cooling
trend, but given we should still have snow cover around would
expect temperatures to fall to the cold side of normal by next
weekend. JKL

&&

.AVIATION...

VFR conditions will prevail across the forecast area today and
tonight. SW winds will increase at KLVM late tonight with gusts of
35-50 kts after 06z, causing local blowing and drifting snow. JKL

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Tue     Wed     Thu     Fri     Sat     Sun
-------------------------------------------------------
BIL 032 021/042 031/047 032/044 029/037 021/034 020/033
    0/N 00/N    00/N    01/N    42/W    12/J    22/J
LVM 037 023/045 031/048 034/046 026/040 018/036 018/035
    0/N 00/N    10/N    13/W    42/W    12/J    22/J
HDN 029 009/039 024/045 025/041 023/036 017/033 013/031
    0/U 00/U    00/B    00/B    42/J    22/J    22/J
MLS 026 012/039 028/041 025/040 023/037 020/032 017/029
    0/U 00/U    00/B    00/B    22/J    22/J    22/J
4BQ 029 011/040 023/045 022/042 021/036 018/034 015/031
    0/U 00/U    00/B    00/B    22/J    22/J    22/J
BHK 025 012/040 027/044 026/041 024/036 019/032 017/029
    0/U 00/U    00/B    00/B    12/J    23/J    22/J
SHR 032 012/040 025/048 024/044 021/037 015/034 012/032
    0/U 00/U    00/B    00/B    42/J    22/J    22/J

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Wind Advisory in effect from midnight tonight to 6 AM MST
      Thursday FOR ZONES 65-66.
WY...None.

&&

$$
weather.gov/billings


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