Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Billings Montana
227 PM MST Wednesday Nov 25 2015
Short term...valid for Thursday and Friday...
Snow continues to fall across the region this afternoon as the
well advertised event has commenced as forecast.
Snowfall reports have been coming...with general 2 to 4 inch
amounts from Billings westward. Expecting the snow to continue
for the rest of the day today especially near Sheridan Wyoming and in
the preferred foothills areas. Amounts should continue to rise
this evening and overnight near Red Lodge as the upslope flow in
the lowest levels of the atmosphere continues to dominate.
Earlier this morning...decided to add Fallon and Custer counties
into the going highlights due to gusty winds...blowing snow and
poor travel conditions. Most of the in storm impacts have faded in
those areas as of this writing...but there remains the potential
for Road conditions and the like into tomorrow and Friday.
As the snow shifts to the east...the story will then become the
cold Canadian air that is firmly in place. Forecast lows for the
next two nights may dip into the negative digits if the skies
clear enough. The coldest air of the season will have an impact on
Holiday activities...so please stay prepared.
At upper levels...a low pressure system continues to spin over the
Great Basin. Infrared imagery shows this system well. The low will
remain cutoff from the main flow into the coming weekend...keeping
the air cold and dry.
Daytime highs will remain in the middle 20s on Thanksgiving day and
Friday as the Canadian ridge continues to build overhead. Singer
Long term...valid for Sat...sun...Mon...Tue...Wed...
Euro and GFS runs continue to be inconsistent in terms of the
upper-level flow pattern through the extended period... thus
providing for low forecast confidence. The upper flow will remain
split Saturday as the polar jet will be well north across Canada
while the sub- tropical jet will be across northern Mexico across
the southwest states. This will keep the upper low currently in
the Great Basin area stationary through Saturday keeping most of
the dynamics to the south of our forecast area ... resulting in
only a slight chance probability of precipitation for snow showers Saturday in the higher
terrain. This upper low finally begins to move northeast across
Wyoming/Montana and into the Dakotas by Sunday morning in the Euro with
little model quantitative precipitation forecast... due to pronounced riding and NE flow aloft in
its wake. The GFS however holds the upper low back west along the
Idaho/Wyoming border... interacting with plains moisture and providing
snowfall along a cyclonic trajectory from the east... to the
north... and then to the west over the course of Sunday into
Monday afternoon. These models individually have been fairly
consistent between 12z runs as of late ... but inter-model
inconsistencies noted above has yielded a difficult determination
of where the upper and surface lows will be situated during the
late weekend period into Monday. In any case...will continue with
a slight chance for snow Sunday into Monday. Beyond this time
period looked to be dry but due to notably different flow patterns
comparing both the Euro and GFS.
Temperatures through the weekend into early next week will remain
below normal but not terribly cold with readings in the 20s to
lower 30s... possibly warming into the upper 30s by Tuesday Onward
but will again be dependent on when upper-level ridging sets in.
Snow over the area this afternoon will gradually taper off from north
to S through tonight...but will persist over the kshr area
through the night. Conditions will be MVFR/IFR in the snow...with
IFR/LIFR around klvm and the foothills. The mountains will be
obscured into this evening and the NE big horns will remain
obscured through Thursday morning. Snow will gradually taper off from north
to S over Sheridan and the NE big horns through the day on Thursday.
The remainder of the area will return to VFR conditions on Thursday. Arthur
Preliminary point temp/pops...
Thursday Friday Sat sun Monday Tuesday Wednesday
bil 004/022 001/025 009/029 017/033 019/037 021/036 021/038
61/b 00/u 01/b 22/j 22/j 11/u 11/u
lvm 003/022 003/025 009/026 012/033 015/036 016/033 016/034
62/S 00/u 01/b 32/j 22/j 11/u 11/u
hdn 004/024 903/028 005/028 016/031 018/035 020/035 019/037
61/b 00/u 01/b 32/j 11/b 11/u 11/u
mls 002/024 001/028 009/030 019/030 015/034 021/035 023/038
21/b 00/u 01/b 22/j 21/b 11/b 01/u
4bq 006/021 903/025 007/028 018/030 016/032 021/035 020/036
84/S 00/u 02/j 42/j 21/b 11/b 11/u
bhk 003/022 001/027 010/030 018/030 016/032 021/032 021/038
21/b 00/u 01/b 23/j 21/b 11/b 11/u
shr 003/018 906/023 004/026 018/031 016/035 020/039 019/039
+6/S 11/u 13/j 33/j 22/j 11/u 11/u
Montana...Winter Storm Warning in effect until 5 am MST Thursday for
Winter Weather Advisory in effect until 5 am MST Thursday for
Winter Weather Advisory in effect until 11 am MST Thursday
for zones 32-33-36>38-57-58.
Wyoming...Winter Weather Advisory in effect until 11 am MST Thursday
for zones 98-99.