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Area forecast discussion...updated
National Weather Service Billings Montana
826 PM MST Fri Feb 24 2017


Snow showers continue to linger over a large portion of the area
this evening. Deformation over the region is beginning to shift
east ever so slowly as the next wave approaches from the
northwest. Shower chances will continue overnight with a weak
frontal boundary sliding through the area before the
aforementioned shortwave moves through the region on Saturday.
Only changes made to the forecast were to increase pops in a few
places to account for current trends. Otherwise, the rest of the
forecast remains on track and the previous forecast discussion and
an updated aviation discussion are below. Stp


Short term...valid for Sat and sun...

No big impactful systems for the short term, but will continue to
see off and on light snow through the period with a brief break
Sunday. Will have to contend with slippery roads again tonight
through tomorrow morning as wet roads freeze up pretty quickly
after sunset.

Deformation lingers over the area this afternoon under a broad
West Coast trof. Main upper low has shifted well into the upper
Midwest this afternoon but energy has gotten orphaned over the
area under this deformation leading to continued light snow and
cloudy conditions. Low level winds are turning westerly this
afternoon over western/central zones but speeds are too light to
completely clear out snow and cloud cover and in areas that have
seen partial clearing instability above 800mb has resulted in
cumulus and light snow shower development. Next piece of upper
level energy is heading this way from SW Canada and is attached to
upper low dropping south along the West Coast. This low is pushing
mid level moisture into the area for the SW Canada wave to work
with and will keep a chance of snow showers in the forecast
through tomorrow under increasingly cyclonic flow aloft. By
tomorrow afternoon low level winds will increase out of the west
helping to dry out the lower levels and give a break in
precipitation chances Saturday night through Sunday.

Yet another piece of energy drops into the Pacific northwest on Sunday
and begins to impact the area late Sunday night into Monday.
Currently models keep this system as an open wave as it moves
into Idaho and across the area. However there are hints of it
trying to close off over southern Idaho which would be a good set
up for precipitation over the western half of the forecast area.
Should still see scattered showers even as an open wave and
adjusted precipitation chances upward to account for the trend. If
the system closes off will need higher pops/snow accumulations.

Temperatures will continue to range in the 25 to 35 range for
highs the next few days, with lows in the teens and 20s. Chambers

Long term...valid for Mon...Tue...Wed...Thu...Fri...

Extended forecast remains relatively consistent...with unsettled
northwesterly flow expected through most of the period.
Temperatures will remain below seasonal average through the bulk
of the period...but will trend upward to end the period.

An upper low deepens and slides into the western Continental U.S.
Monday...but stays south far enough to keep US in cooler zone
through mid week. Meanwhile a Lee-side surface low and associated
warm front shifts northward Monday...bringing showers to
mountains, foothills, and Central Plains. Unsettled northwest flow
aloft keeps isolated snow chances in the mountains and foothills
through the end of the week. Overall little accumulation is
expected outside high terrain.

Winds may be a bigger concern, as models suggest several waves sliding
west to east along the Canadian border for latter half of the
week while the ridge sits over southern Idaho. This pattern may
yield several periods of gusty winds from Livingston northeastward
to Harlowton. Breezy conditions advertised in grids looks good at
this time...but will need further attention as windy period gets
closer. Aag



Isolated to scattered snow showers will affect the area tonight
through Saturday, then taper off from west to east Sat. Evening. Expect
MVFR/IFR conditions with the snow showers. Patchy fog is possible
late tonight with MVFR conditions as well. There will be areas of
mountain obscuration through the period. Arthur


Preliminary point temp/pops...

Sat sun Mon Tue Wed Thu Fri
bil 018/032 018/033 017/031 017/033 020/041 025/043 028/050
33/j 12/j 33/j 22/j 11/north 22/west 12/west
lvm 012/026 014/028 011/028 011/028 017/036 023/040 028/049
34/j 23/j 44/j 42/j 22/j 22/west 12/west
hdn 022/034 018/037 019/035 018/036 019/043 022/046 026/055
33/j 11/b 33/j 22/j 21/b 22/west 12/west
mls 022/035 019/037 018/035 021/035 021/042 024/043 027/049
22/j 11/b 24/j 22/j 12/west 21/b 12/west
4bq 021/034 018/036 018/038 020/036 020/043 024/044 025/051
23/j 11/b 23/west 22/j 21/north 21/east 11/north
bhk 017/031 015/034 014/032 016/031 017/037 020/039 024/046
23/j 21/b 23/j 22/j 22/west 21/b 12/west
shr 014/029 011/031 010/032 013/031 014/039 019/042 022/052
22/j 21/b 12/j 12/j 21/b 22/j 11/b


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