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Area forecast discussion 
National Weather Service Billings Montana
238 PM MST Thursday Nov 26 2015

Short term...valid for Friday and Sat...

Persistent upper level low will remain over the Great Basin
through the weekend. Friday looks very quiet but energy wrapping
around the system Saturday will bring increasing clouds and a
chance for snow. Models continue to show a significant amount of
uncertainty with possible precipitation Saturday into Sunday. NCEP
gefs rmop predictability over the area through Monday is in the
10 to 30 percent range...very low for the early forecast periods.
Wpc guidance suggests leaning on GFS and its ensembles and away
from more variable European model (ecmwf) with this package and trended forecast
that way.

Tonight...clear skies...fresh snow cover and light winds will
combine for a quick drop in temperatures this evening as the sun
sets. Temperatures will drop into the lower teens this evening and
to around zero for sunrise tomorrow. Drainage winds of 5 to 10 miles per hour
will add bitter wind chills to the equation at times as well.
Those heading out shopping tonight and tomorrow morning should be
prepared for bitter cold temperatures.

For Friday convergence aloft will continue to produce subsidence
over the area for sunny conditions and a bit warmer temperatures.
Highs should reach the middle to upper 20s. Clouds will increase over
southern areas Friday night which will help temperatures stay a
bit warmer than tonight. Otherwise a dry and cold night on tap
Friday night.

Energy wrapping into the area from the south...around the Great
Basin low looks to tap into rich plains moisture feed to bring a
chance of snow to the area Saturday into Saturday night. Dynamics
are not terribly strong but there is enough forcing for a dusting
to a couple of inches of snow during this period. A lot of
uncertainty remains with this system even this close in
keeping probability of precipitation and snow accumulations broadbrushed for the time
being. Expect to be able to tighten up this forecast on subsequent
shifts. Highs on Saturday will be mainly in the 20s as cloud cover
locks in colder overnight air and limits mixing potential. Chambers

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

Great Basin upper low will continue to impact weather over the
area through Tuesday and possibly Wednesday in southeast Montana.
As mentioned in the short term discussion the model clarity with
this system is well below average. Cips analogs show a very poor
correlation with this system as well so keeping forecast very
broadbrushed and leaning on ensemble means for this forecast

Sunday into Monday upper low slides across Wyoming and into
Nebraska and the Dakotas. This puts the forecast area in the
northern portion of this system which is good for precipitation
development. The exact track will have a lot to do with how much
precipitation develops and exactly where it falls. This system
continues to tap at least a bit of a strong plains moisture feed
so if it moves in just the right track there is the potential for
significant snow with it. Given the uncertainty though will keep
precipitation chances and precipitation/snow amounts broadbrushed
and fairly low...with a couple of inches over southeast Montana.
Will keep a close eye on this system this weekend.

Once this system exits Tuesday or possibly as late as Wednesday
will see a dry and more zonal pattern develop for the middle and
later portion of the week...bringing warming temperatures to the
region. Chambers


VFR conditions and light winds will prevail across the region
this evening and overnight. Aag


Preliminary point temp/pops...

Friday Sat sun Monday Tuesday Wednesday Thursday
bil 003/025 007/028 015/029 018/032 021/034 022/040 025/044
00/u 03/S 32/S 21/b 00/b 00/u 00/b
lvm 905/026 005/030 013/029 012/033 018/036 018/038 022/043
00/u 02/S 32/S 20/b 00/b 00/north 01/north
hdn 001/026 005/029 012/028 017/031 019/038 018/041 019/043
00/u 03/S 32/S 21/b 10/b 00/u 00/b
mls 000/026 004/028 014/029 019/030 019/036 017/039 020/041
00/u 02/S 22/S 43/S 20/b 00/u 00/b
4bq 000/025 006/029 012/028 018/029 018/036 015/040 018/044
00/u 03/S 23/S 43/S 20/b 00/u 00/b
bhk 901/027 005/030 014/029 018/029 017/034 014/039 018/042
00/u 01/u 22/S 43/S 21/b 10/u 00/b
shr 901/024 006/026 009/026 014/029 016/038 013/040 018/044
00/u 04/S 43/S 33/S 21/b 00/u 00/b


Byz watches/warnings/advisories...



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