Winter Storm Warning 9, NWS Great Falls, MT

934 
WWUS45 KTFX 170105
WSWTFX

URGENT - WINTER WEATHER MESSAGE
National Weather Service Great Falls MT
705 PM MDT Tue Jun 16 2020

MTZ008-015-052-055-171800-
/O.CON.KTFX.WS.W.0009.200617T0300Z-200617T1800Z/
Beaverhead-Madison-Jefferson-Gallatin-
Including Big Hole Pass, Wisdom, Monida Pass, Wise River, 
Raynolds Pass, Virginia City, Boulder Hill, Elk Park Pass, 
Homestake Pass, West Yellowstone, Battle Ridge Pass, 
Bozeman Pass, and Targhee Pass
705 PM MDT Tue Jun 16 2020

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL NOON MDT
WEDNESDAY ABOVE 5500 FEET...

* WHAT...Heavy snow expected above 5500 feet. Total snow
  accumulations of up to 12 inches, with some higher amounts on
  the highest peaks of Southwest Montana.


* WHERE...Elevation above 5500 feet in Gallatin, Madison, 
  Jefferson and Beaverhead Counties.

* WHEN...Until noon MDT Wednesday.

* IMPACTS...Travel could be very difficult along roads entering 
  mountain areas. Hazardous backcountry conditions for those 
  outdoors and campers. The weight of the snow on branches with 
  foliage could cause them to break and produce isolated power 
  outages or blocked roads.

* ADDITIONAL DETAILS...This Winter Storm Warning is for 
  elevations above 5500 feet and does not include the cities of 
  Bozeman, Ennis, or Dillon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency.

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1.

&&

Moldan

$$

MTZ014-171800-
/O.NEW.KTFX.WW.Y.0037.200617T0300Z-200617T1800Z/
Central and Southern Lewis and Clark-
705 PM MDT Tue Jun 16 2020

...WINTER WEATHER ADVISORY IN EFFECT UNTIL NOON MDT WEDNESDAY
ABOVE 5500 FEET...

* WHAT...Wet snow expected above 5500 feet. Total snow
  accumulations of up to 6 inches.

* WHERE...Elevations above 5500 feet in Central and Southern Lewis
  and Clark County, which includes MacDonald Pass.

* WHEN...Until noon MDT Wednesday.

* IMPACTS...Plan on slippery road conditions. The hazardous
  conditions could impact the morning commute over MacDonald Pass.

* ADDITIONAL DETAILS....This Winter Weather Advisory does not
  include the city of Helena or Helena Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1. 

&&

Moldan

$$

http://www.weather.gov/greatfalls

102 
WWUS45 KTFX 171002
WSWTFX

URGENT - WINTER WEATHER MESSAGE
National Weather Service Great Falls MT
402 AM MDT Wed Jun 17 2020

MTZ008-052-171800-
/O.CON.KTFX.WS.W.0009.000000T0000Z-200617T1800Z/
Beaverhead-Jefferson-
Including Big Hole Pass, Wisdom, Monida Pass, Wise River, 
Boulder Hill, Elk Park Pass, and Homestake Pass
402 AM MDT Wed Jun 17 2020

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL NOON MDT TODAY
ABOVE 5500 FEET...

* WHAT...Heavy snow occurring above 5500 feet. Additional snow
  accumulations of up to 4 inches on mountain passes, with another
  7 to 12 inches possible in the mountains above 7000 feet.

* WHERE...Jefferson and Beaverhead Counties above 5500 feet.

* WHEN...Until noon MDT today.

* IMPACTS...Travel could be very difficult along roads entering
  mountain areas, and on mountain passes such as Monida Pass, Big
  Hole Pass, Homestake Pass, and Elk Park Pass. Backcountry 
  conditions will be hazardous for those outdoors and campers. The
  weight of the snow on branches with foliage could cause them to
  break and produce isolated power outages or blocked roads.

* ADDITIONAL DETAILS...This Winter Storm Warning is for elevations
  above 5500 feet and does not include the cities of Dillon,
  Whitehall, and Boulder.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If you must travel, keep an extra flashlight, food, and water in
your vehicle in case of an emergency.

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1. 

&&

$$

MTZ015-055-171800-
/O.CON.KTFX.WS.W.0009.000000T0000Z-200617T1800Z/
Madison-Gallatin-
Including Raynolds Pass, West Yellowstone, and Targhee Pass
402 AM MDT Wed Jun 17 2020

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL NOON MDT TODAY
ABOVE 6500 FEET...

* WHAT...Heavy snow occurring above 6500 feet. Additional snow
  accumulations of up to 2 inches on Bozeman Pass, Raynolds Pass,
  and Targhee Pass, and another 5 to 9 inches in the mountains 
  above 7000 feet.

* WHERE...Gallatin and Madison Counties above 6500 feet.

* WHEN...Until noon MDT today.

* IMPACTS...Travel could be difficult on mountain passes due to
  slick and slushy conditions. Backcountry conditions will also be
  hazardous for those outdoors and campers. The weight of the 
  snow on branches with foliage could cause them to break and 
  produce isolated power outages or blocked roads.

* ADDITIONAL DETAILS...This Winter Storm Warning is for elevations
  above 6500 feet and does not include the cities of Bozeman,
  and Ennis.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1. 

&&

$$

MTZ014-171800-
/O.CON.KTFX.WW.Y.0037.000000T0000Z-200617T1800Z/
Central and Southern Lewis and Clark-
402 AM MDT Wed Jun 17 2020

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL NOON MDT TODAY
ABOVE 5500 FEET...

* WHAT...Snow occurring above 5500 feet. Additional snow
  accumulations of up to two inches on MacDonald Pass, and up to 5
  inches above pass level.

* WHERE...Central and Southern Lewis and Clark County above 5500
  feet.

* WHEN...Until noon MDT today.

* IMPACTS...Plan on slippery road conditions. The hazardous
  conditions could impact the morning commute over MacDonald Pass.

* ADDITIONAL DETAILS....This Winter Weather Advisory does not
  include the city of Helena or Helena Valley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. 

The latest road conditions for the state you are calling from can
be obtained by calling 5 1 1. 

&&

$$

http://www.weather.gov/greatfalls

054 
WWUS45 KTFX 171517
WSWTFX

URGENT - WINTER WEATHER MESSAGE
National Weather Service Great Falls MT
917 AM MDT Wed Jun 17 2020

MTZ008-015-052-055-171630-
/O.CAN.KTFX.WS.W.0009.000000T0000Z-200617T1800Z/
Beaverhead-Madison-Jefferson-Gallatin-
917 AM MDT Wed Jun 17 2020

...WINTER STORM WARNING IS CANCELLED...

Snow will still be possible for elevations above 7000 ft but only
minimum impacts are expected. Conditions will still be cold and 
raw for those recreating outdoors.

$$

MTZ014-171630-
/O.CAN.KTFX.WW.Y.0037.000000T0000Z-200617T1800Z/
Central and Southern Lewis and Clark-
917 AM MDT Wed Jun 17 2020

...WINTER WEATHER ADVISORY IS CANCELLED...

Snow is no longer expected to cause hazardous conditions. 
However, it will still be cold and raw for those recreating 
outdoors.

$$

http://www.weather.gov/greatfalls

Area Forecast Discussion
National Weather Service Great Falls MT
1216 PM MDT Tue Jun 16 2020

.UPDATE...

Some minor tweaks needed this morning based on current radar
trends. Rain showers have spread a little further north today,
which have been the main adjustments today. These showers in the
north may diminish or become scattered later today, while they
remain in the south. Tonight into Wednesday continues to look
unsettled with widespread rain. Mountain snow is also a
possibility, with perhaps some impacts to those outdoors. Winter
Storm Watch is currently in effect, and will be looked into more closely
this afternoon. Anglin

&&

.SYNOPSIS...

A large scale, slow moving storm system will produce widespread
rain and mountain snow across the region through Thursday.
Temperatures will range about 10 to 15 degrees below average.
Isolated thunderstorms this afternoon could produce locally heavy
rainfall rates and small hail.

&&

.AVIATION...
Updated 1200 PM MDT Mon Jun 15 2020 (16/18Z TAF Period)

Periods of MVFR to perhaps IFR conditions will be found throughout
much of the forecast period due to unsettled weather. Today
through this evening many areas will see rain showers bring MVFR
conditions, with VFR conditions in-between. Showers then look to
be confined in the southwest this evening, before becoming
widespread tonight into Wednesday. MVFR to perhaps IFR conditions
are possible with this second round tonight into Wednesday.
Mountain snow is also possible in the southwest, brining
obscuration. An unseasonably low freezing level with deep clouds
and light rain will lead to icing on ascent/descent.

NOTE: Amendments not scheduled for Ennis (KEKS) due to ongoing
runway closure.

&&

.PREV DISCUSSION...
/ISSUED 1130 AM MDT Tue Jun 16 2020/

A large scale closed upper level low will slowly migrate across
the Northwestern U.S. today through Thursday. As such, we will
continue to experience below average temperatures and periods of
widespread rain and mountain snow.

Most of the precipitation today and tonight will spread across
Southwest into central Montana, already seen developing early this
morning on radar. Weak instability beneath a strongly divergent
flow aloft could enable a few embedded thunderstorms this
afternoon, capable of producing locally heavy rainfall rates and
small hail. The 700 mb trough axis crosses the region overnight,
helping to lower snow levels to around 5500 feet across Southwest
Montana. A combination of cold advection and dynamical cooling
associated with the prolonged period of ascent is likely to bring
snow levels below that indicated by model guidance. Thus, forecast
snow accumulation and snow levels are still showing some
variation among the ensemble members, as well as variations in the
location of heaviest precipitation. A winter storm watch remains
in effect for Southwest Montana, but has been raised from 5000
feet to 6000 feet, as expected impacts from accumulating wet snow
now appear at a higher elevation compared to the prior forecast.
Nonetheless, with most backcountry areas open to recreation, snow
accumulations of even a few inches should be considered
significant for this late in the season.

After the mid-level trough axis moves into eastern Montana on
Wednesday, winds shift to northwesterly and a secondary surge of
precipitation develops across Central into Southwest Montana.
Periods of rain and mountain snow continue Wednesday night through
Thursday as the storm system lingers over the region. There is
rather low confidence in the end time for precipitation, as models
vary widely on this outcome. Overall, it is a three day
precipitation event with rainfall amounts of 1 to 2 inches for
central and Southwest Montana, with lesser amounts up to one-half
inch across much of North-central Montana including the HiLine.

The upper low finally drifts far enough away to the east on Friday
to enable partial clearing, but still supporting showers under an
unstable northwest flow aloft. Warmer air returns with fair
weather later Friday through next weekend. Current forecasts bring
temperatures back into the 80s by Sunday, with warm weather
persisting into the following week.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  62  45  59  47 /  70  60  90  60
CTB  65  45  61  47 /  30  40  90  70
HLN  59  43  58  46 /  80  90 100  50
BZN  54  40  55  42 /  80  70 100  50
WYS  49  35  49  31 /  90  70  90  50
DLN  54  39  50  37 /  90  90 100  20
HVR  64  48  66  49 /  50  40  90  70
LWT  55  41  56  44 /  80  70 100  70

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from 6 PM MDT this evening through Wednesday
morning above 6000 feet for Beaverhead...Gallatin...Jefferson...
Madison.

&&

http://www.weather.gov/greatfalls