Area Forecast Discussion
Issued by NWS Great Falls, MT
FXUS65 KTFX 061138
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
435 AM MST Fri Dec 6 2013
...UPDATE TO AVIATION...
Today through Sunday...with a strong area of surface high pressure
moving southward out of Central Canada into Northern
Montana...expect a very cold day across the region today.
Afternoon high temperatures will likely not go above 10 below zero
in many areas of North Central MT...while the Southwest will be a
tad warmer...with highs generally around zero. Because of the very
cold temperatures and light winds...wind chill values are running
near 40 below in many areas. Thus the wind chill advisory is being
changed to a wind chill warning. There is some potential that
winds will remain strong enough this afternoon/tonight for a wind
chill highlight to continue and we will let day shift take another
look and see if the wind chill highlight needs to be extended.
Overnight lows tonight will be near 30 below in many areas over
North Central MT. Otherwise there will be a chance for mainly late
morning/afternoon light snow to develop over Southwest MT today ahead
of the next area of low pressure. The main area of low pressure
will move through Central Utah on Saturday...resulting in a chance
for snow to continue on Saturday...mainly south of a Butte to
Bozeman line. Snow accumulations should generally be less than an
inch from tonight through Saturday in the Southwest. Expect
slightly warmer temperatures on Saturday...but still very cold.
For Sunday...the flow aloft generally remains northerly...but the
coldest air also pulls off to our east. Thus slightly warmer air
moves in by the afternoon hours...but temperatures will still be
close to 25 degrees below normal. Also...an upper level
disturbance moves southward through the region on Sunday producing
some light accumulating snowfall. Brusda
Sunday Night through Friday...Medium range models remain in good
agreement and are consistent with the trend of warming temperatures
next week. Upper level trough currently over the region moves
eastward Sunday night and Monday. This puts Montana in an unsettled
northwest flow aloft through the end of the period. Model solutions
diverge later in the week as shortwave energy timing and location
varies between the two models, but the large scale pattern is
consistent. Overall pattern continues to look favorable for an
increasing temperature trend through Thursday. The unsettled flow
and occasional shortwave energy remains favorable for slight chance
to low chance pops across the forecast area but there still does not
appear to be any likelihood for a large scale storm system through
Thursday. However, by Friday models suggest that a backdoor cold
front will push back into North Central Montana with an increasing
chance of light snow across the forecast area with temperatures
dropping once again. mpj
An upper level low and associated Arctic airmass will remain over
the Northern Rockies through Saturday morning. Areas of low and mid
level clouds producing flurries or light snow will cause MVFR
conditions at times but VFR conditions should prevail at most TAF
locations through the period. Winds will remain generally light. mpj
.PRELIMINARY POINT TEMPS/POPS...
GTF -13 -28 -4 -16 / 20 10 10 0
CTB -13 -32 -5 -19 / 10 10 0 0
HLN 2 -12 2 -8 / 30 20 20 0
BZN -2 -21 0 -18 / 20 40 30 0
WEY 2 -26 10 -16 / 40 60 50 20
DLN -1 -15 4 -13 / 40 50 30 0
HVR -14 -31 -6 -23 / 10 10 0 0
LWT -10 -26 -3 -20 / 30 20 20 0
WIND CHILL WARNING until 11 AM MST this morning Blaine...
Broadwater...Cascade...Central and Southern Lewis and Clark...
Chouteau...Eastern Glacier...Eastern Pondera...Eastern Teton...
Northern Rocky Mountain Front...Southern Rocky Mountain Front...