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Area forecast discussion...updated 
National Weather Service Billings Montana
932 am MST Monday Mar 2 2015

made some notable changes this morning...mainly for the west-southwest
product. Based on what I have seen so far from 12z model data and
trends...some of our snowfall totals seem overdone. I do not plan
on changing any of our highlights at this point...but have re-
written the west-southwest product to emphasize reduced visibility in
blowing/drifting snow and slick roads rather than snow amounts. I
have reduced snowfall totals...especially over the plains from
Roundup to Billings and eastward. The main impact area still looks
to be the foothills and nearby areas where wind and snowfall will
make dangerous travel conditions tonight. Most of the mountains
will not see warning criteria...but north facing slopes could see
an outside shot of a foot such as at Red Lodge mountain. Bt


Short term...valid for today and Tuesday...

A strong Arctic front has moved through Calgary. Current timing
has the front moving through Judith Gap by early afternoon...and
through the area by late afternoon...early evening. Ahead of the
front...temperatures will warm into the middle to upper 30s...mainly
with prefrontal warming. Highs will be early...mainly in the
morning to early afternoon...with temperatures falling rapidly
after the front passes through.

Dynamics with system continue to look strong...especially this
evening and overnight. The heaviest snowfall continues to be in
the beartooth...absaroka...and Bighorn Mountains...where over a
foot of new snowfall is possible. The foothills will also see 6
to 12 inches. The winter storm watches have been upgraded to
warnings...and have issued winter weather advisories for the
plains adjacent to the warnings...from
Roundup...through Billings and Hardin...and Powder River and
Custer counties. Snow will begin tapper off by tomorrow morning
and will move out by tomorrow afternoon.

Along with the falling snow...winds will be strong behind the
front...20 to 25 miles per hour...with gusts 30 to 40 miles per hour possible. This
will create blowing snow issues..especially in the Judith Gap
area and along the foothills. Also with Arctic air in place wind
chills will drop into the teens to 20s below zero. Reimer

Long term...valid for Wednesday...Thu...Fri...Sat...sun...

Northwest flow will prevail over the region behind the early week
system. A few disturbances are embedded in this flow but models
having trouble resolving placement of these features. As a result
a blend of model solutions washes out most of this energy
resulting in a generally dry forecast. The one time frame that
shows the most Promise for precipitation looks to be Friday night
into Saturday. Yesterdays GFS runs showed a decent disturbance
sliding down The Spine of The Rockies...and the latest European model (ecmwf) now
shows this solution as well. However the latest GFS has this
feature now staying well north of the area. Went ahead and put in
some low probability of precipitation for western areas to account for this potential wave
and will see if consistency improves over time. Temperature
guidance continues to show a warming trend through the week with
highs pushing 50 degrees by Friday. Chambers


VFR conditions will prevail through middle afternoon. A strong cold
front will move in from the northwest after 20z resulting in
strong northerly winds. By 00z...ceilings will rapidly decrease as
snow develops behind the front. Periods of moderate to heavy snow
and blowing snow will impact most locations...mainly along and
west of a Roundup-kbil-kshr line this evening with IFR or lower
conditions prevailing into Tuesday morning. Chambers/hooley


Preliminary point temp/pops...

Today Tuesday Wednesday Thursday Friday Sat sun
bil 038 003/015 905/027 009/044 028/052 029/051 030/052
1/b 85/j 10/b 00/b 01/b 22/west 11/u
lvm 037 001/012 906/029 015/044 027/051 029/051 030/052
2/west 95/j 10/b 00/north 11/north 21/b 11/b
hdn 039 007/017 904/027 007/047 022/055 026/052 026/053
0/b 75/j 10/b 00/b 01/b 12/west 11/b
mls 036 002/011 906/014 901/042 022/049 024/046 025/045
0/b 42/j 20/b 00/b 01/b 11/b 11/b
4bq 038 004/014 905/016 000/041 018/049 021/047 022/048
0/b 73/j 10/b 00/b 01/b 12/west 11/b
bhk 034 000/010 909/011 902/040 019/047 021/044 021/042
0/u 42/j 20/b 00/b 01/b 11/b 11/b
shr 037 005/010 910/016 005/040 019/048 024/045 022/048
0/b 97/j 10/b 00/b 01/b 22/west 11/u


Byz watches/warnings/advisories...
Montana...Winter Weather Advisory in effect until 9 am MST Tuesday for
zones 28-29-42.
Winter Storm Warning in effect from 6 PM this evening to noon
MST Tuesday for zones 34-38>41-56-64>67.
Winter Weather Advisory in effect from 6 PM this evening to
noon MST Tuesday for zones 35>37-57-58.
Winter Storm Warning in effect until 9 am MST Tuesday for
zone 63.
Wyoming...Winter Storm Warning in effect from 6 PM this evening to noon
MST Tuesday for zones 98-99.



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