Wind Advisory 11, NWS Missoula, MT

000 
WWUS75 KMSO 011744
NPWMSO

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE MISSOULA MT
1044 AM MST SUN DEC 1 2013

IDZ007-008-021500-
/O.CON.KMSO.WI.Y.0011.131201T1800Z-131202T1500Z/
OROFINO/GRANGEVILLE REGION-LOWER HELLS CANYON/SALMON RIVER REGION-
944 AM PST SUN DEC 1 2013

...WIND ADVISORY REMAINS IN EFFECT UNTIL 7 AM PST MONDAY FOR THE
CAMAS PRAIRIE...GRANGEVILLE AND HIGHWAY 95...

A WIND ADVISORY FOR THE CAMAS PRAIRIE...GRANGEVILLE AND HIGHWAY
95 REMAINS IN EFFECT UNTIL 7 AM PST MONDAY. 

* IMPACTS/TIMING: STRONG SOUTH WINDS WILL CONTINUE THROUGH EARLY
  MONDAY MORNING NEAR GRANGEVILLE. HIGH PROFILE VEHICLES AND SEMI
  TRUCKS SHOULD USE CAUTION WHEN TRAVELING THROUGH THESE AREAS.

* WINDS: SOUTH 25 TO 35 MPH SUSTAINED WITH GUSTS UP TO 55 MPH 
  ARE POSSIBLE. 

* LOCATIONS IMPACTED INCLUDE...CAMAS PRAIRIE...GRANGEVILLE AND 
  VICINITY...HIGHWAY 95 SLATE CREEK TO RIGGINS...WHITE BIRD GRADE

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WIND ADVISORY MEANS THAT WINDS OF 35 MPH ARE EXPECTED. WINDS
THIS STRONG CAN MAKE DRIVING DIFFICULT...ESPECIALLY FOR HIGH
PROFILE VEHICLES. USE EXTRA CAUTION.

&&

$$

000 
WWUS75 KMSO 021439
NPWMSO

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE MISSOULA MT
739 AM MST MON DEC 2 2013

IDZ007-008-021545-
/O.EXP.KMSO.WI.Y.0011.000000T0000Z-131202T1500Z/
OROFINO/GRANGEVILLE REGION-LOWER HELLS CANYON/SALMON RIVER REGION-
639 AM PST MON DEC 2 2013

...WIND ADVISORY WILL EXPIRE AT 7 AM PST THIS MORNING FOR THE
CAMAS PRAIRIE...GRANGEVILLE AND HIGHWAY 95...

THE WIND ADVISORY FOR THE CAMAS PRAIRIE...GRANGEVILLE AND HIGHWAY
95 WILL EXPIRE AT 7 AM PST THIS MORNING. 

* LOCATIONS IMPACTED INCLUDE...CAMAS PRAIRIE...GRANGEVILLE AND 
  VICINITY...HIGHWAY 95 SLATE CREEK TO RIGGINS...WHITE BIRD GRADE

$$

Area Forecast Discussion
National Weather Service Missoula MT
353 PM MST Sat Nov 30 2013

...HEAVY MOUNTAIN SNOW FOLLOWED BY ARCTIC AIR MONDAY NIGHT...

.DISCUSSION...

Tonight a complex weather system really starts to impact the
region. Because this is such a complex storm system, we want to
highlight the biggest impacts that are expected:

1) HEAVY MOUNTAIN PASS AND BACK COUNTRY SNOWFALL: An atmospheric
river of tropical origins is currently making its way towards the
west coast and the Cascades. After causing heavy rain and flooding
there, the moisture plume will head eastward and impact the
northern Rockies. Areas of upslope flow in central Idaho and
western Montana will be hardest hit. This river will bring strong
winds and 200 percent of the normal amount of water to the western
slopes of the northern Rockies.

Mountain snow will be measured in feet with this system by the
time it is done, and Lolo, Lost Trail, and Lookout passes will be
have heavy snow tomorrow afternoon and evening. Those on
back country roads should be prepared for heavy snow so as to not
become trapped.

2) VALLEY RAIN CHANGING TO SNOW/CHANCE FOR MIXED PRECIP: While the
heavy snow is impacting the mountains, many of the valleys will be
warm enough for rain. Some isolated pockets of cold air may
persist in northwest Montana and cause very localized icy
conditions. Freezing rain Sunday morning is expected to be much
less than this morning. Throughout the night precipitation may
turn from rain to snow, and then possibly back to rain again
Monday morning.

Expect variable and rapidly changing conditions in the valleys of
northwest Montana, especially in the foothills surrounding the
valleys. Travel conditions will be difficult with the potential
for snow, slush, and ice through Monday morning.

3) ARCTIC FRONT: Timing is difficult as models still cannot agree
upon when the arctic front will arrive. The current consensus is
for northwest Montana to be impacted Monday late afternoon or late
evening and the front moves across western Montana and central
Idaho by late Tuesday morning. Confidence is high that the cold
air is coming, however timing remains uncertain.

There are several impacts that will make being outdoors or
traveling next week difficult and dangerous at times.
- Flash freezing of wet roads with the arrival of the cold air
- Low visibility and difficulty driving with blowing snow
- North winds 20-30 mph, especially through Hellgate and Bad Rock
canyons.
- Wind chills below -20 across northwest Montana Wednesday morning
- Coldest temperatures in 2 1/2 years from central ID through
western MT

The pattern will remain very cold through next weekend, with only
marginal chances of additional light snowfall. Overnight
temperatures will consistently be in the sub-zero and single digit
range for western Montana valleys, while central Idaho valleys
will be only slightly warmer. Daytime temperatures will remain
well below freezing. There is little sign of a pattern change
even after next weekend.

&&

.AVIATION...

Periodic snow/rain showers will impact aviation across the
Northern Rockies during the next 24 hours. Valley fog and freezing
fog will persist within some valleys, while others will experience
low stratus. Terrain obscurations will be commonplace during this
time. The snow/rain showers will become much more numerous after
01/1800Z, marking the beginning of a prolonged winter storm
scenario over the region.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH from Sunday evening through late Tuesday
     night Butte/Blackfoot Region...Missoula/Bitterroot Valleys.

     WINTER STORM WARNING from 11 PM this evening to 1 AM MST
     Wednesday Bitterroot/Sapphire Mountains...Lower Clark Fork
     Region...Potomac/Seeley Lake Region...West Glacier Region.

     WINTER STORM WATCH from Sunday morning through late Tuesday
     night Flathead/Mission Valleys.

     WINTER STORM WATCH from 11 PM MST this evening through late
     Tuesday night Kootenai/Cabinet Region.

ID...WINTER STORM WATCH from Sunday evening through late Tuesday
     night Eastern Lemhi County...Western Lemhi County.

     WINTER STORM WARNING from 10 PM this evening to Midnight PST
     Tuesday Night Northern Clearwater Mountains...Southern
     Clearwater Mountains.

&&

Leach/Zumpfe
Aviation...Zumpfe

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