High Wind in Montana, December 19, 2016

Area Forecast Discussion
National Weather Service Great Falls MT
1038 PM MST Sun Dec 18 2016

.UPDATE AVIATION...

.UPDATE DISCUSSION...

Forecast appears on track with increasing winds spreading east
across North Central Montana tonight through Monday. Will
therefore keep the High Wind Warnings in effect as is. Not seeing
any significant reduction of visibility in blowing snow. Am
suspecting that many areas already have crusted over snow.
However, with as strong as winds are and will become, am still
expecting some areas of blowing snow before the majority of the
snow is crusted over with near freezing temperatures and
additional sun tomorrow. Will therefore leave the Advisories for
blowing snow in effect as well. Temperatures will likely not fall
much over the plains overnight due to the wind, but partial
clearing and lighter winds in the valleys of Southwest Montana
will allow temperatures there to fall into the single digits above
and below zero.  Coulston

&&

.PREV DISCUSSION...
/ISSUED 447 PM MST Sun Dec 18 2016/

Tonight through Tuesday...Broad upper level ridge with fast WNW
flow aloft over Western Canada/US flattens quickly tonight as
upper trough from the Gulf of AK crashes into BC with surface low
pressure emerging east of the Rockies in northern Alberta Monday
morning while a 120+kt upper jet noses inland along the
US/Canadian border. Strengthening surface pressure gradient
across the Rockies and increasing winds aloft will maintain windy
conditions across the plains of northcentral MT overnight while
already strong winds along the Rocky Mtn Front and adjacent areas
increase further, particularly after midnight. Shortwave energy,
surface trough and upper level jet energy associated with the
incoming upper trough move quickly ESE across the forecast area
Monday, setting the stage for widespread strong winds across much
of north central MT. Models continue to advertise 60-70kt winds at
8-10kft with 75-85kt winds at this level over the Northern Rockies
in addition to favorable conditions for Mtn wave action with a
stable layer and lesser winds above 8-10kft. Will upgrade the
remainder of the High Wind Watch for north-central MT beginning
late tonight and extend the duration of the high wind warning
through Monday evening. Will also beef up the wording in the wind
warning to mention higher gusts, particularly along the front
range. Blowing and drifting snow will also continue to impact
some areas, though the settling and scouring of snow over the last
24hrs appears to have mitigated visibility from being
significantly reduced in many areas that have already been
gusting to 40 mph today. Will continue the Winter wx advisory for
blowing snow across n-central MT and extend its duration through
Monday morning. By Monday afternoon, temperatures across much of
n-central MT should be near the freezing point, further mitigating
the blowing snow hazard, but with widespread gusts 50-60mph
cannot rule out some localized blowing/drifting snow hazards
continuing. Winds diminish some Monday night behind the passage of
the shortwave and surface trough, but remain on the windy side and
look to increase again on Tuesday as another shortwave moves in
quickly from the west. Snow will also spread east as across the
forecast area Tuesday as the wave moves across the region, through
west winds will likely keep precip and any snow accumulations on
the low end for locations east of the continental divide. Hoenisch

Tuesday Night through Sunday...Shortwave trof that initially arrives
on Tues will continue to make its way through our forecast area
through early Wed morning, bringing scattered areas of light snow.
Forecast still mentions possibility of rain/snow mix for area
bounded by Great Falls-Havre-northern Fergus County around sunset on
Tues, but mixed precip duration would be short as surface cold front
should arrive shortly after sunset and switch precip to all snow.
Clearing skies expected Wed aftn that will continue through Thurs
morning as shortwave ridge tracks across the state.  Next weather
system follows on Thurs aftn/eve, taking a similar track to the
Tues/Wed system but with pockets of light snow lingering slightly
longer behind the system on Fri. Continuity between GFS and ECMWF
models breaks down starting Fri night, with the GFS keeping us dry
under a broad high pressure ridge, while the EC sends a third
Pacific shortwave into MT on Sat/early Sun. Confidence at this point
is low on which solution might win out, so current forecast
compromises with dry conditions for the central and Hiline counties
and 20-30 percent chance for light snow over southwest MT. Looks
like high temperatures will stay near- to slightly above-freezing
for Wed and Thurs for all areas except for southern Beaverhead/
Madison/Gallatin counties which remain in the 20s.  All locations
cool back into the 20s for Fri thru Sun as the weather system on Fri
brings in a colder airmass behind it. Waranauskas

&&

.AVIATION...
/Updated 0600Z/

VFR conditions with periods of mid level clouds to prevail
through the forecast period...however...strong winds are expected
to develop...and may bring areas of blowing snow at times. Winds
of over 40 knots are already being found in the KCTB area...with
gusts over 30 knots already found from KGTF to KLWT and north to
KHVR. Winds will only further increase tonight into Monday...with
over 50 Knot gusts possible from KCTB to KGTF To KLWT and north by
Monday afternoon. Sites across the south will see not as high of
gusts...but still some breezy winds at times. Blowing snow may
slightly reduce visibility at times in strong winds. Wind shear is
also mentioned in select TAF sites for tonight given the
strengthening winds off the surface. With strong cross mountain
flow...some strong mountain wave turbulence...possibly in clear
air...is expected at times. Anglin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  19  35  26  40 /  10  10  10  40
CTB  18  33  22  37 /  10  10  10  40
HLN   0  23  15  39 /  10  10  20  50
BZN   0  22  13  36 /  10  10  20  50
WEY -15  14   8  25 /  10  30  40  70
DLN   2  23  16  37 /  10  10  20  50
HVR  17  35  21  37 /  10  10  10  30
LWT  16  35  23  38 /  10  10  10  50

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
High Wind Warning until 11 PM MST Monday Blaine...Cascade...
Central and Southern Lewis and Clark...Chouteau...Eastern
Teton...Fergus...Hill...Judith Basin...Liberty...Toole.

Winter Weather Advisory until 11 AM MST Monday Cascade...Central
and Southern Lewis and Clark...Eastern Glacier...Eastern
Pondera...Eastern Teton...Judith Basin...Liberty...Northern
Rocky Mountain Front...Southern Rocky Mountain Front...Toole.

High Wind Warning until 11 PM MST Monday Eastern Glacier...
Eastern Pondera...Northern Rocky Mountain Front...Southern Rocky
Mountain Front.

Winter Weather Advisory until 11 AM MST Monday Blaine...
Chouteau...Fergus...Hill.

&&

weather.gov/greatfalls

PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE GREAT FALLS MT
927 PM MST SUN DEC 18 2016

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1221 PM     NON-TSTM WND GST 8 SE EAST GLACIER PARK  48.36N 113.11W
12/18/2016  M83 MPH          GLACIER            MT   MESONET

            MESONET STATION DEEP CREEK RAWS /DCRM8/.

0300 AM     NON-TSTM WND GST 10 NNE BOZEMAN          45.80N 110.93W
12/18/2016  M73 MPH          GALLATIN           MT   MESONET

            MESONET STATION BRIDGER BOWL - SLUSHMANS
            LIFT /BBSLH/.

0800 AM     NON-TSTM WND GST 12 NE BOZEMAN           45.82N 110.90W
12/18/2016  M66 MPH          GALLATIN           MT   MESONET

            MESONET STATION BRIDGER BOWL - BASE /BBBAS/.

0915 AM     NON-TSTM WND GST 14 W BYNUM              47.98N 112.61W
12/18/2016  M66 MPH          TETON              MT   MESONET

            MESONET STATION 13 W BYNUM /DELMT/.

0206 PM     NON-TSTM WND GST 1 ENE EAST GLACIER PARK 48.45N 113.20W
12/18/2016  M60 MPH          GLACIER            MT   MESONET

            MESONET STATION TWO MEDICINE BRIDGE MDT
            /MTBRN/.

0847 PM     NON-TSTM WND GST 3 SW CUT BANK           48.60N 112.38W
12/18/2016  M58 MPH          GLACIER            MT   ASOS

            ASOS STATION CUT BANK AIRPORT /CTB/.

0809 PM     NON-TSTM WND GST 18 WSW BYNUM            47.87N 112.67W
12/18/2016  M56 MPH          TETON              MT   MESONET

            MESONET STATION GLEASON RAWS /GSNM8/.

0852 PM     NON-TSTM WND GST 7 ESE HILGER            47.22N 109.22W
12/18/2016  M56 MPH          FERGUS             MT   MESONET

            MESONET STATION JUDITH PEAK /JPKM8/.

0100 PM     NON-TSTM WND GST SUNBURST                48.88N 111.90W
12/18/2016  M54 MPH          TOOLE              MT   MESONET

            MESONET STATION SUNBURST MDT /MTSUN/.

0516 AM     NON-TSTM WND GST 4 W HAVRE               48.54N 109.76W
12/18/2016  M52 MPH          HILL               MT   ASOS

            ASOS STATION HAVRE AP ASOS /HVR/.

0516 AM     NON-TSTM WND GST 4 W HAVRE               48.54N 109.76W
12/18/2016  M52 MPH          HILL               MT   ASOS

            ASOS STATION HAVRE AP ASOS /HVR/.

0735 PM     NON-TSTM WND GST 2 SSE GEYSER            47.25N 110.48W
12/18/2016  M51 MPH          JUDITH BASIN       MT   MESONET

            MESONET STATION GEYSER MDT /MTGYS/.

0821 PM     NON-TSTM WND GST 2 NW PENDROY            48.07N 112.33W
12/18/2016  M51 MPH          TETON              MT   MESONET

            MESONET STATION PENDROY MDT /MTPND/.

1211 PM     NON-TSTM WND GST SAINT MARY              48.74N 113.43W
12/18/2016  M50 MPH          GLACIER            MT   MESONET

            MESONET STATION SAINT MARY RAWS /SRYM8/.

0229 PM     NON-TSTM WND GST 15 WNW WOLF CREEK       47.09N 112.37W
12/18/2016  M50 MPH          LEWIS AND CLARK    MT   MESONET

            MESONET STATION ROGERS PASS MDT /MTROG/.

0820 PM     NON-TSTM WND GST 6 NNW SUNBURST          48.96N 111.94W
12/18/2016  M46 MPH          TOOLE              MT   MESONET

            MESONET STATION SWEET GRASS MDT /MTSWT/.

0158 PM     NON-TSTM WND GST MALMSTROM AFB           47.50N 111.19W
12/18/2016  M45 MPH          CASCADE            MT   AWOS

            AWOS STATION MALMSTROM AFB /GFA/.

1239 PM     NON-TSTM WND GST 5 WSW GREAT FALLS       47.47N 111.38W
12/18/2016  M44 MPH          CASCADE            MT   ASOS

            ASOS STATION GREAT FALLS AIRPORT /GTF/.

0807 PM     NON-TSTM WND GST 1 N LOMA                47.95N 110.50W
12/18/2016  M44 MPH          CHOUTEAU           MT   MESONET

            MESONET STATION LOMA MDT /MTLOM/.

0327 PM     NON-TSTM WND GST 4 NNE MCALLISTER        45.50N 111.70W
12/18/2016  M42 MPH          MADISON            MT   MESONET

            MESONET STATION NORRIS HILL MDT /MTNOR/.

0315 PM     NON-TSTM WND GST 1 WSW CONRAD            48.17N 111.98W
12/18/2016  M40 MPH          PONDERA            MT   AWOS

            AWOS STATION CONRAD APT /KS01/.

1233 PM     NON-TSTM WND GST 1 W CHINOOK             48.59N 109.25W
12/18/2016  M40 MPH          BLAINE             MT   MESONET

            MESONET STATION CHINOOK /S719/.

1223 PM     HIGH SUST WINDS  3 SW CUT BANK           48.60N 112.38W
12/18/2016  M40 MPH          GLACIER            MT   ASOS

            SUSTAINED WIND 40 MPH WITH GUSTS TO 55 MPH
            AT CUT BANK AIRPORT.

1000 AM     NON-TSTM WND GST 1 NNE CHOTEAU           47.83N 112.17W
12/18/2016  M39 MPH          TETON              MT   AWOS

            AWOS STATION CHOTEAU AWOS /KCII/.

0208 PM     NON-TSTM WND GST 2 SW LEWISTOWN          47.05N 109.46W
12/18/2016  M38 MPH          FERGUS             MT   ASOS

            ASOS STATION LEWISTOWN AP ASOS /LWT/.

0526 PM     NON-TSTM WND GST 12 E BOZEMAN            45.67N 110.80W
12/18/2016  M34 MPH          GALLATIN           MT   MESONET

            MESONET STATION BOZEMAN PASS MDT /MTBZH/.

0655 PM     NON-TSTM WND GST 5 NNE CAMERON           45.27N 111.65W
12/18/2016  M33 MPH          MADISON            MT   AWOS

            AWOS STATION ENNIS BIG SKY /EKS/.

0456 PM     NON-TSTM WND GST 5 NE DILLON             45.26N 112.55W
12/18/2016  M31 MPH          BEAVERHEAD         MT   ASOS

            ASOS STATION DILLON AIRPORT /DLN/.

0110 PM     NON-TSTM WND GST 1 NNW WEST YELLOWSTONE  44.68N 111.12W
12/18/2016  M30 MPH          GALLATIN           MT   AWOS

            AWOS STATION W YELLOWSTONE AWOS - 1 NW WEST
            YELLOWSTONE /WYS/.

0253 PM     NON-TSTM WND GST 2 WNW EAST HELENA       46.61N 111.96W
12/18/2016  M21 MPH          LEWIS AND CLARK    MT   ASOS

            ASOS STATION HELENA AP ASOS /HLN/.

&&

NWS GREAT FALLS MT
IRIS SYSTEM