Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 221647

947 AM MST Mon Dec 22 2014

.UPDATE...Areas of snow across the forecast area will gradually
weaken and taper off through the rest of the day. While mountain
peaks may see a few more inches of accumulation, it appears that
lower elevations and passes will not see any significant amounts.
As a result, I have cancelled the Winter Weather Advisory. Have
made some minor tweaks to PoPs and sky condition for today and
tonight but temperatures and winds appear to be on track at this
time so no changes were made to these elements. mpj


Northwest flow pattern aloft will continue over central and
southwest MT today.  Weak disturbances and pockets of moisture in
the flow will create isolated/scattered snow showers, along with VFR
ceilings. Given spotty nature of the showers, have kept any mention
as VCSH at local terminals. Winds will be breezy across much of the
region from 18-02Z, with gusts in the 20-25 kt range.


/ISSUED 430 AM MST Mon Dec 22 2014/
Today through Thursday...An upper level trof continues to slowly
move through the region...with areas of light snow continuing to
affect the Rocky Mountain Front and mainly the mountains of
Southwest MT. Most of the accumulating snowfall is above pass
level over the Rocky Mountain this area has been
dropped from the advisory. In Southwest MT...snow continues to
affect some passes...especially around Butte. Thus this region has
been extended until about 11 am this morning. Otherwise...fairly
quiet weather conditions are expected over much of the remainder
of the region today through Tuesday. Temperatures today will not
climb much more than the current cold air advection
slowly moves into the region. Afternoon highs on Tuesday will be a
touch cooler than today. For Wednesday...the next storm system
will approach the region. This storm system is now forecasted
about 8 hours slower than previous runs. Thus the bulk of the
accumulating snowfall will not begin on Wednesday evening.
Additionally it will be windy and mild on Wednesday...especially
over the northern Plains. For now...mid level winds are progged
right near warning criteria over the Rocky Mountain Front...but I
will hold off on any wind highlights at this time. Periods of
rain/snow develop over much of the region Wednesday
night...becoming mostly snow by early Christmas morning. Overall
forecasted snowfall amounts from Wednesday through Christmas Day
look to be very similar to previous runs...with 2 to 5 inches at
lower elevations and 6 to 12 inches in the mountains...with
isolated higher amounts. Snow amounts in the Havre area continue
to be only around an inch or two. Winter weather highlights will
likely be needed for this event. Temperatures will be colder on
Christmas Day as well across the region. Brusda

Thursday night through Monday. Upper-level trof that
moves through our region in the midweek period now looks to linger
over the Central and Southwest Counties into Friday morning. The
main area of moisture accompanying the trof is still expected to
head toward Southeast MT on Thurs night, so any additional snowfall
into Friday morning should be light.  The system fully exits the
state by Fri night, with a short period of high pressure ridging and
dry conditions forecast for Sat.  The next weather system makes its
initial approach into MT on Sat night, and like the midweek trof,
makes a somewhat slow progression through our region on Sun.  Latest
GFS and ECMWF model solutions for the second system are not in close
agreement at this point, with the GFS moving the system about 6-12
hrs quicker than the ECMWF.  However, both models line up well on
maintaining slightly colder-than-average high temperatures, with
daily highs only reaching the mid 20S through Mon.


GTF  41  21  37  30 /  10  10  10  10
CTB  37  20  35  30 /  10  10  20  10
HLN  39  18  33  23 /  30  10  10  10
BZN  37   8  25  15 /  30  10  10  10
WEY  32   6  27  13 /  50  20  10  10
DLN  36  12  30  20 /  40  10  10  10
HVR  39  20  37  26 /  10  10  10  10
LWT  38  21  37  29 /  20  20  10  10



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