High Wind in Montana, February 2, 2018

Area Forecast Discussion
National Weather Service Great Falls MT
841 PM MST Fri Feb 2 2018

.UPDATE...

A few updates needed for ongoing precipitation trends this
evening. The biggest update was for the precipitation for northern
and central portions. Freezing rain made it slightly further north
than anticipated this evening...all the way up to Havre. This
mixed precip may linger a few more hours before diminishing.
Meanwhile...downsloping dry air has limited precip to only the
mountains across the remaining portions of the CWA. Went ahead and
lowered pops for these dry areas for this evening. Models indicate
a brief break in precip during much of the overnight hours. Made
some pop adjustments for this break. The next round of mainly
snow will impact the area from north to south on Saturday with the
passage of a strong front. Gusty winds ahead and with this front
may also be found. Areas with fresh snow could see some blowing
snow. This wind could also bring some bitterly cold wind chills
to the Hi-Line area.

No changes were made to the current highlights. Rocky Mountain
Front and other mountain Winter Weather Advisories will see one
more push of mainly light snow this evening before diminishing.
The Winter Weather Advisory across the plains is also covering the
mixed precipitation quite well. And the Winter Storm Watch covers
nicely the next round(s) of snow. Would anticipate a second look
at the Advisories during the early overnight hours as it
coincides with the mentioned break in precipitation. Anglin

&&

.SYNOPSIS...

Several rounds of wintry precipitation will impact Central Montana
through early next week. While mostly snow is expected there, there
is a brief window of opportunity for a wintry mix later today and
this evening near Fort Benton. Across Southwest Montana,
temperatures will fluctuate quite a bit, with snow mixing with or
changing to rain at times. Active winter weather may continue well
into next week.

&&

.AVIATION...
Updated 0000z.

Multiple rounds of precip will bring areas of MVFR to IFR
conditions throughout the forecast period. The first round of
rain...snow...and possibly freezing rain will be found this
evening mainly from KHVR to KGTF to KBZN to KEKS and eastward
including KLWT. These areas could see MVFR to IFR showers at
times. Meanwhile...the remainder of the area will be breezy with
increased clouds but mainly VFR conditions. A brief lull in
activity is then expected during the early to late overnight
hours...with most sites seeing VFR conditons. A sharp cold front
then pushes from north to south on Saturday bringing the next
round of mainly snow along with a breezy northerly wind shift.
Most sites will have chances for MVFR to IFR and possibly LIFR
snow. Conditions will continue to worsen during the evening and
overnight hours on Saturday night. Anglin

&&

.PREV DISCUSSION...
/ISSUED 509 PM MST Fri Feb 2 2018/

Multiple rounds of precipitation will impact our forecast area
through Monday with several winter weather hazards expected. Later
next week, a very similar setup to this weekend may develop, with
more winter precip/hazards.

As for specific details, most of the focus with this forecast
centers around three distinct shortwaves that are expected to
traverse the state through Monday. A fast-moving system through
this evening will bring a quick shot of precipitation, with mixed
precipitation possible from near Lake Elwell along the Hi-Line
southeast through Choteau County and into northern and eastern
Fergus County. To the north, mainly toward Havre and points north
and east, precipitation should remain all snow with accumulations
up to 2 inches expected. The Winter Weather Advisory remains in
effect for these areas through late this evening into the early
overnight, as the combination of snow, sleet, and/or freezing
rain will make roads very slick in spots.

Disturbances will continue to move roughly parallel to an arctic
front across the plains through much of Saturday, resulting in
periods of snow with varying intensity levels. Accumulations
during this time will favor the mountains, with lighter amounts
across the plains. A strong disturbance with associated strong
cold front pushes south from Canada late Saturday afternoon, and
will move quickly south through the evening and overnight. Expect
widespread heavier snow as this system and cold front move through
the area. Accumulations will be widespread, with especially
significant accumulations for those areas with slopes facing to
the north. Another factor with this strong cold front will be the
plummeting temperatures behind the front, with low temperatures 20
below or lower and wind chills possibly reaching as low as 40
below zero across parts of north-central Montana Saturday night.

Sunday will start with extremely cold temperatures across the
area. With previous days storm systems delivering a fresh coating
of snow, temperatures will have no problem starting out in the -15
to -25 degree range across the Hi-Line, with sub-zero
temperatures all across northern and central Montana. Impacts in
this time frame include dangerously cold wind chills as winds
remain breezy at times during the morning hours. Wind chills
of -20 to -40 or less may be very possible, with highlights
likely to follow in later days. Otherwise, snowfall associated
with storm #2 will start to diminish in intensity and drift south,
with a slight drying opportunity possible for NE areas. This will
be short lived though as storm #3 arrives Sunday afternoon with
widespread snow likely once again across a large majority of
north-central, central and south-central MT delivering additional
snowfall accumulations. Expect snow to continue across the same
areas through Sunday night and into early Monday. It wont be until
later on Monday night when snow finally begins to diminish and
press to the southeast of the area, leaving behind continued cold
temperatures in place. With some lingering snow possible in the
SW, fortunately most of the CWA may lean towards the dry side
through Tuesday.

In the extended, latest long-range guidance has trended slightly
drier from Tuesday through Thursday, however given this persistent
northwesterly flow cemented in place across the Northern Rockies, we
can't rule out some lingering snow flurries or light snow showers
at times. There very well could be yet another system rolling
through here late Thursday and into Friday, with moderating
temperatures possible. But in summary for the long range, expect
this active pattern to persist with a locked-in winter pattern
expected. KLG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  35  38  -6  21 /  20  90 100  60
CTB  15  22  -7  17 /  30  80 100  60
HLN  38  41   5  31 /  50  60 100  50
BZN  34  43  14  36 /  50  60 100  60
WEY  28  34  25  33 /  80  70  50  70
DLN  33  43  26  42 /  30  20  40  40
HVR  11  12 -21   5 /  90 100 100  10
LWT  30  31 -14  21 /  90 100 100  50

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 11 PM MST this evening Central and
Southern Lewis and Clark...Northern Rocky Mountain Front...
Southern Rocky Mountain Front.

Winter Storm Watch from 5 AM MST Saturday through Monday
afternoon Blaine...Broadwater...Cascade...Central and Southern
Lewis and Clark...Chouteau...Eastern Glacier...Eastern Pondera...
Eastern Teton...Fergus...Gallatin...Hill...Jefferson...Judith
Basin...Liberty...Meagher...Northern Rocky Mountain Front...
Southern Rocky Mountain Front...Toole.

Winter Weather Advisory until 1 AM MST Saturday Blaine...
Chouteau...Fergus...Hill...Liberty.

Winter Weather Advisory until 2 AM MST Saturday above 5000 feet
for Cascade...Gallatin...Judith Basin...Madison...Meagher.

&&

http://www.weather.gov/greatfalls

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
935 PM MST FRI FEB 2 2018

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

0810 PM     FREEZING RAIN    1 S HAVRE               48.54N 109.68W
02/02/2018  M0.13 INCH       HILL               MT   TRAINED SPOTTER

            SPOTTER REPORTS DIFFICULT TRAVEL IN HAVRE
            DUE TO A MIX OF FREEZING RAIN AND SNOW. AN
            EIGHTH OF AN INCH OF ICE ACCUMULATION WAS
            MEASURED. AS OF THIS REPORT, THE FREEZING
            RAIN HAS CHANGED BACK TO ALL SNOW.

&&

MARTIN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
937 PM MST FRI FEB 2 2018

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

0521 PM     NON-TSTM WND GST TWO MEDICINE BRIDGE MDT 48.45N 113.20W
02/02/2018  M64 MPH          GLACIER            MT   MESONET

&&

MARTIN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
938 PM MST FRI FEB 2 2018

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

0818 PM     NON-TSTM WND GST HELENA AP ASOS          46.61N 111.96W
02/02/2018  M54 MPH          LEWIS AND CLARK    MT   ASOS

&&

MARTIN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
939 PM MST FRI FEB 2 2018

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

0743 PM     NON-TSTM WND GST SIEBEN FLATS MDT        46.89N 112.11W
02/02/2018  M51 MPH          LEWIS AND CLARK    MT   MESONET

&&

MARTIN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
940 PM MST FRI FEB 2 2018

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

0758 PM     NON-TSTM WND GST 10 ESE BOZEMAN          45.63N 110.83W
02/02/2018  M50 MPH          GALLATIN           MT   MESONET

            ELEVATION 6397 FEET.

&&

MARTIN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
951 PM MST FRI FEB 2 2018

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

0751 PM     NON-TSTM WND GST SIEBEN FLATS MDT        46.89N 112.11W
02/02/2018  M58 MPH          LEWIS AND CLARK    MT   MESONET

            CORRECTS PREVIOUS NON-TSTM WND GST REPORT
            FROM SIEBEN FLATS MDT.

&&

MARTIN