Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus65 kbyz 150215 

Area forecast discussion
National Weather Service Billings Montana
715 PM MST Thu Dec 14 2017

quiet night of weather tonight other than the increasing wind out
west. Already seeing gusts of 30-40 mph at Big Timber and
Harlowton, courtesy of cold air and high pressures in the valleys
of south central Montana. Have raised wind speeds at these sites in the
evening, and lowered them a bit at Livingston where gusts are
under 20 mph. As Pacific shortwave approaches and Lee side
pressure falls turn the gradient to a more favorable direction, we
should see winds at The Gap areas increase later tonight into
Friday. Will make no changes to the wind advisories in effect for
Livingston and Nye. Otherwise, have adjusted forecast lows down a
few degrees in eastern valleys and at Sheridan as temps have
already fallen to the low 20s. Jkl


Short term...valid for Fri and Sat...

Much of the differences between the GFS and the NAM have resolved
themselves. The GFS has backed off the winds shifting to the
northeast with a convergence band across the central zones. Snow
amounts generally look like 1 to 2 inches on the plains. Now that
the models are more in agreement that winds into the foothills
will become northeasterly, upsloping will result in 3 to 4 inches
in the foothills, and down around Sheridan. The higher elevations
will see amounts around 6 to 10 inches. There will be some
convectively enhanced bands with this system, similar to the Dec
2-3 system, but at this point it is still a little early to know
where these bands will setup.

Before the snowfall Friday night into Saturday, Friday still looks
to be a windy and mild pre-frontal day. Winds around Livingston
and Nye will be 55 to 65 mph, so have issued a Wind Advisory.
Winds still looks to be strong around bit Timber and Harlowton,
with gusts up to 50 to 55 mph. Fire weather conditions still look
to be elevated with the temps pushing into the lower 50s, but
there will be some increasing clouds during afternoon around peak
heating. For now will hold off on the rangeland fire danger
statement. Reimer

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

An unsettled weather pattern looks to continue over the region
through the long term with models progging multiple disturbances
impacting the area. The first system looks to drop out of the
northwest bringing a chance for snow to the area on Monday and
Tuesday. A more substantial system is then progged to move through
the area Wednesday and Thursday bringing in colder air and
increasing snow chances. High pressure then looks to build into
the region for Thursday, with possibly another system moving
through the area on Friday as Arctic air moves south. While
models are in general agreement in the overall pattern, timing and
placement differences do exist. High temperatures in the 30s and
40s can be expected through Wednesday, with highs dropping into
the 20s on Thursday. Stp



VFR conditions will prevail through the taf period with passing
mid and high clouds overhead. Southwest to west winds will
increase along the western foothills this evening with gusts of 40
to 50 kt possible late tonight into Friday from klvm to k6s0, and
north through khwt. Breezy west winds are expected elsewhere.


Preliminary point temp/pops...

Fri Sat sun Mon Tue Wed Thu
bil 031/051 030/035 020/037 028/043 026/042 031/039 014/024
00/north 67/j 21/u 13/r 22/west 24/o 31/east
lvm 030/045 027/033 017/035 027/042 030/045 034/039 014/023
00/north 88/j 31/b 23/r 32/west 25/o 32/j
hdn 025/052 030/037 019/038 026/044 025/042 028/040 012/024
00/b 67/west 10/u 13/r 22/j 24/o 42/j
mls 023/050 029/037 020/038 026/042 023/039 025/038 012/022
00/b 44/j 10/u 12/r 22/j 13/o 42/j
4bq 023/052 029/037 020/037 025/044 024/041 026/042 014/024
00/b 36/west 10/u 13/r 21/b 13/r 52/j
bhk 019/047 027/035 018/036 024/040 022/036 022/036 010/021
00/b 33/j 10/u 12/o 11/b 13/S 52/j
shr 019/053 028/035 016/037 022/043 022/042 026/042 014/023
00/u 58/j 41/u 12/r 22/j 13/r 42/j


Byz watches/warnings/advisories...
Montana...Wind Advisory in effect until 6 PM MST Friday for zones

National Weather Service Glossary of Abbreviations