High Wind in Montana, February 25, 2018

Area Forecast Discussion
National Weather Service Great Falls MT
400 AM MST Sun Feb 25 2018

.SYNOPSIS...

Strong west winds return today, creating blizzard conditions
along the Rocky Mountain Front with areas of blowing snow expected
across the remainder of north-central Montana. Snowfall will
continue over the mountains of the Continental Divide with snow
expected to develop over southwest Montana Sunday night and
continue through Monday.

&&

.DISCUSSION...

Today through Tuesday...February continues to send Montana
extremely nasty weather conditions that most of us are ready to
say goodbye to. Unfortunately, before that can happen we need to
get through continued cold and very windy conditions in the short
term period. Received spotter reports from East Glacier region
reporting continued blizzard conditions this morning so have gone
ahead and upgraded the Winter Weather Advisory to *another*
Blizzard Warning for the Rocky Mountain Front. Have left the
remainder of the existing advisory as-is but have some concerns
that a few areas over the plains may flirt with high wind criteria
today. However, it appears that if any areas outside the Rocky
Mountain Front *do* see gusts exceeding criteria they should be
isolated and likely a one-hit wonder so have opted to not issue
any wind warnings for now. Mountain snow is expected today/tonight
for along the Continental Divide with snow and blowing snow
developing over southwest Montana this evening. Have issued a
second Winter Weather Advisory for the far southwest Montana
counties for tonight and Monday with areas of blowing snow
expected to dissipate Monday afternoon. It's also worth noting
that accumulating snows could continue in the West Yellowstone
region into Monday night so it is possible this area may need to
have the advisory extended. Then, just because it's winter in
Montana, *another* upper level wave will bring a surge of moisture
and increasing winds over my western zones for Tuesday. At this
time it does not appear that winds will be as strong as those of
today. However, I wouldn't be too surprised to see another round
of blowing snow and miserable conditions along the Rocky Mountain
Front once again. mpj

Tuesday Night through Sunday...Models have come into very good
agreement for this period, so confidence is increasing in the
overall solution. A northwest flow aloft on the back side of an
exiting shortwave low pressure trough will likely keep light snow in
the mountains of western and southwest Montana Tuesday night into
Wednesday, but breezy westerly downslope winds will keep lower
elevations dry. A weak shortwave high pressure ridge will then help
dry out most of the forecast area for Wednesday night. The next
system to potentially have a significant impact on the region will
be a deep upper level low pressure trough that will move south along
the Pacific coast of Canada Wednesday night to the Pacific Northwest
coast on Thursday. The increasingly moist southwest flow aloft over
the forecast area will keep a good chance of snow over the western
and southwest mountains Thursday and Thursday night. The trough will
then broaden as it spreads east across the Pacific Northwest and
into Montana Friday through Saturday, which may cause at least light
snow to spread over the forecast area. It is still a bit too early
to tell how much snowfall will occur, but this situation will need
to be monitored for possible winter weather highlights. This system
will begin exiting the area on Sunday for a decreasing chance of
snow. Temperatures will be 5 to 10 degrees below normal for the
beginning of this period. However, they will steadily cool to
between 10 and 15 degrees below normal Saturday through Sunday with
the passage of a Canadian cold front associated with the system.
Coulston

&&

.AVIATION...
Updated 0541Z

Variable mid- and high-level clouds will prevail across Montana
overnight through late Sunday evening. Areas of snow remain possible
across southwest Montana through the forecast period for IFR/MVFR
conditions and mountain obscurations at times. Widespread VFR
conditions prevail over north-central and central Montana but strong
and gusty westerly winds will cause localized IFR/MVFR conditions in
blowing snow, especially along the Rocky Mountain Front. mpj

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  14  29  10 /  10  20  10   0
CTB  33  11  29  12 /  10  20  10   0
HLN  35  14  30   5 /  20  30  20   0
BZN  32  15  28  -1 /  30  50  50  20
WEY  19  14  24  -6 /  90  90 100  60
DLN  27  13  24  -2 /  30  60  50  20
HVR  32  12  24   6 /  10  10  10   0
LWT  33  16  27   6 /  10  20  10   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight MST tonight Central and
Southern Lewis and Clark.

Winter Weather Advisory until midnight MST tonight Blaine...
Cascade...Chouteau...Eastern Glacier...Eastern Pondera...Eastern
Teton...Fergus...Hill...Judith Basin...Liberty...Toole.

Winter Weather Advisory from 6 PM this evening to 6 PM MST
Monday Beaverhead...Gallatin...Madison.

Blizzard Warning until midnight MST tonight Northern Rocky
Mountain Front...Southern Rocky Mountain Front.

&&

http://www.weather.gov/greatfalls