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000
FXUS65 KMSO 301015
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
415 AM MDT THU OCT 30 2014

...Significant Snow Possible on Mountain Passes This Weekend...

.DISCUSSION...A weather disturbance late Friday and into the
weekend will bring wet weather and colder conditions to the
Northern Rockies. There is a possibility of significant mountain
and higher-elevation valley snow and perhaps a wintry mix to the
lower valleys.

Expecting a foggy start to the day for most valleys as a moist
airmass lingers in the region and weak inversions develop. A moist
Pacific system will spread wet weather across the Pacific NW
today; however, forecast models indicate it will mostly remain to
our west, with with the chance of rain limited to far northwest
Montana. Elsewhere, mid-slope temperatures should warm as a warmer
airmass moves in from the south, but valleys may not see much of a
warm-up with inversions struggling to break given the time of year
and cloudy skies. More valley fog is likely tonight with a
continued moist boundary layer and a bit of clearing overnight.

For Halloween, expect a warmer day in general as a warmer airmass
moves in and some southerly breezes allow for a bit more mixing.
Clouds will increase by the afternoon meanwhile as another
weather disturbance approaches the area. Central Idaho and
northwest Montana will probably see light rain in time for trick-
or-treating, while the Kalispell- Missoula- Salmon corridor and
eastward should remain dry through at the least the evening hours.

A significant weather system is forecast to impact much of the
Northern Rockies this weekend, bringing with it heavy snow above
5000ft and perhaps a mix of rain and snow as low as 3500ft.
Locations across southwest Montana (i.e Butte, Georgetown Lake,
Lost Trail/Homestake/MacDonald/Skalkaho Passes), west central
Montana (Lolo Pass & Seeley Lake) and north central Idaho (i.e
Dixie, Gilmore Summit & Bannock Pass) still appear to be the most
significantly impacted by heavy snowfall amounts between 4 and 10
inches (up to 18 inches in the backcountry) starting Saturday
morning and continuing into Sunday afternoon. The latest weather
models are maintaining a fairly consistent path and timing to the
system with perhaps a slight trend towards a slower, more westerly
solution. This actually lends increased confidence in the forecast
of snow across the Bitterroot, Mission and Swan Mountain Ranges as
well as a greater likelihood for rather wet conditions for many
western Montana valleys below 5000ft this weekend. It also
maintains already high confidence in the snowfall potential for
southwest Montana.

The snow level is expected to drop Saturday night as the low
exits into North Central Montana and fall to around 3500ft
(perhaps lower) by Sunday morning. Any accumulation at these lower
elevations is still expected to be very light and pose minimal
impacts. Precipitation should decrease through the afternoon and
Sunday evening for all but the Seeley/Swan/Glacier National Park
areas and largely be finished by Monday morning.

An active pattern looks to continue into next week, with
occasional rounds of wet weather under westerly flow aloft. The
best chance of precipitation will be those areas favored under
westerly flow, such as the Cabinet Range and other ranges of
northwest Montana, as well as most of central Idaho. Snow levels
are expected to rise above pass level through this period,
limiting the winter impacts to the higher elevations.

&&

.AVIATION...Moist conditions in the valleys will lead to patchy
fog and low clouds, causing reduced visibilities and periodic low
ceilings at KMSO and KGPI through mid-morning. Conditions should
begin to slowly improve around mid-morning. Elsewhere, mostly
cloudy skies will continue with light winds.



&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$






000
FXUS65 KMSO 292021
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
220 PM MDT WED OCT 29 2014

...SNOW OVER MOUNTAIN PASSES THIS WEEKEND...

.DISCUSSION...High pressure and drier air will build over the
region tonight. Clearing skies and low level moisture from last
night`s rains will be the ingredients for widespread fog across
most valley locations. Northwest Montana and central Idaho`s lower
valleys will be impacted the most with the thickest fog. Expect
mainly patchy fog elsewhere.

An upper level ridge will remain over the region through mid-day
Friday. Temperatures will remain somewhat cool under valley
inversions with mid level clouds moving through the ridge.
However, the airmass will be warmer on Friday despite weak inversions
that will hinder temperatures from reaching their full potential.
High temps will be above normal rising into the mid and upper
50s.

Enjoy the next two days as a significant wet weather disturbance
is expected to impact the entire region this weekend.

There is high certainty that a trough will pass through the
region on Saturday and that widespread precipitation will fall
beginning late Saturday. Forecast confidence is also high for
cooler temperatures and lowering snow levels by Sunday. When
weather systems similar to this have impacted the region in the
past the main focus for precipitation has been in north central
Idaho, through southwest Montana, and along the Continental
Divide. Current model solutions agree with this precipitation
placement so the current forecast reflects the same geographic
focus. There are subtle differences in the low placement and focus
for heaviest precipitation, so although confidence is high for the
storm system, there is some question on where the most moisture
and heaviest snow will fall. Snow levels will start off fairly
high early Saturday and lower to between 3000-4000 feet by late
Sunday. Most people have a chance to see snow with a good chance
for moderate snow amounts in the high terrain and over mountain
passes through Sunday night. Road conditions over mountain passes
such as Homestake, Lost Trail, Bannock, MacDonald, and Marias are
expected to be impacted as this system passes.

The region will begin to dry out on Monday but rain and snow
showers remain under northwesterly flow aloft.

Beyond Monday next week, models are pretty inconsistent as they
show either dry conditions under a flat ridge or another very wet
weather disturbance around midweek. Given the low confidence in
any model solution climatology will be used. During the first
week of November the average high temperatures are only in the
upper 40s.

&&

.AVIATION...Moist westerly flow combined with relatively unstable
conditions will allow for scattered showers in the mountains this
afternoon through this evening. So expect some mountain
obscuration through at least 30/0900z across western Montana. Some
drier air will work in aloft late tonight and this combined with
light surface winds will help fog to develop especially KMSO and
KGPI. The fog will dissipate by mid-morning Thursday. For the most
part most valleys will be rather stable on Thursday while there
will be an increasing chance for rain showers across Lincoln
County, Montana (Troy/Yaak areas) by evening.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$






000
FXUS65 KMSO 292019
AFDMSO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
219 PM MDT WED OCT 29 2014

...SNOW OVER MOUNTANI PASSES THIS WEEKEND...

.DISCUSSION...HIGH PRESSURE AND DRIER AIR WILL BUILD OVER THE
REGION TONIGHT. CLEARING SKIES AND LOW LEVEL MOISTURE FROM LAST
NIGHT`S RAINS WILL BE THE INGREDIENTS FOR WIDESPREAD FOG ACROSS
MOST VALLEY LOCATIONS. NORTHWEST MONTANA AND CENTRAL IDAHO`S LOWER
VALLEYS WILL BE IMPACTED THE MOST WITH THE THICKEST FOG. EXPECT
MAINLY PATCHY FOG ELSEWHERE.

AN UPPER LEVEL RIDGE WILL REMAIN OVER THE REGION THROUGH MID-DAY
FRIDAY. TEMPERATURES WILL REMAIN SOMEWHAT COOL UNDER VALLEY
INVERSIONS WITH MID LEVEL CLOUDS MOVING THROUGH THE RIDGE.
HOWEVER, THE AIRMASS WILL BE WARMER ON FRIDAY DESPITE WEAK INVERSIONS
THAT WILL HINDER TEMPERATURES FROM REACHING THEIR FULL POTENTIAL.
HIGH TEMPS WILL BE ABOVE NORMAL RISING INTO THE MID AND UPPER
50S.

ENJOY THE NEXT TWO DAYS AS A SIGNIFICANT WET WEATHER DISTURBANCE
IS EXPECTED TO IMPACT THE ENTIRE REGION THIS WEEKEND.

THERE IS HIGH CERTAINTY THAT A TROUGH WILL PASS THROUGH THE
REGION ON SATURDAY AND THAT WIDESPREAD PRECIPITATION WILL FALL
BEGINNING LATE SATURDAY. FORECAST CONFIDENCE IS ALSO HIGH FOR
COOLER TEMPERATURES AND LOWERING SNOW LEVELS BY SUNDAY. WHEN
WEATHER SYSTEMS SIMILAR TO THIS HAVE IMPACTED THE REGION IN THE
PAST THE MAIN FOCUS FOR PRECIPITATION HAS BEEN IN NORTH CENTRAL
IDAHO, THROUGH SOUTHWEST MONTANA, AND ALONG THE CONTINENTAL
DIVIDE. CURRENT MODEL SOLUTIONS AGREE WITH THIS PRECIPITATION
PLACEMENT SO THE CURRENT FORECAST REFLECTS THE SAME GEOGRAPHIC
FOCUS. THERE ARE SUBTLE DIFFERENCES IN THE LOW PLACEMENT AND FOCUS
FOR HEAVIEST PRECIPITATION, SO ALTHOUGH CONFIDENCE IS HIGH FOR THE
STORM SYSTEM, THERE IS SOME QUESTION ON WHERE THE MOST MOISTURE
AND HEAVIEST SNOW WILL FALL. SNOW LEVELS WILL START OFF FAIRLY
HIGH EARLY SATURDAY AND LOWER TO BETWEEN 3000-4000 FEET BY LATE
SUNDAY. MOST PEOPLE HAVE A CHANCE TO SEE SNOW WITH A GOOD CHANCE
FOR MODERATE SNOW AMOUNTS IN THE HIGH TERRAIN AND OVER MOUNTAIN
PASSES THROUGH SUNDAY NIGHT. ROAD CONDITIONS OVER MOUNTAIN PASSES
SUCH AS HOMESTAKE, LOST TRAIL, BANNOCK, MACDONALD, AND MARIAS ARE
EXPECTED TO BE IMPACTED AS THIS SYSTEM PASSES.

THE REGION WILL BEGIN TO DRY OUT ON MONDAY BUT RAIN AND SNOW
SHOWERS REMAIN UNDER NORTHWESTERLY FLOW ALOFT.

BEYOND MONDAY NEXT WEEK, MODELS ARE PRETTY INCONSISTENT AS THEY
SHOW EITHER DRY CONDITIONS UNDER A FLAT RIDGE OR ANOTHER VERY WET
WEATHER DISTURBANCE AROUND MIDWEEK. GIVEN THE LOW CONFIDENCE IN
ANY MODEL SOLUTION CLIMATOLOGY WILL BE USED. DURING THE FIRST
WEEK OF NOVEMBER THE AVERAGE HIGH TEMPERATURES ARE ONLY IN THE
UPPER 40S.

&&

.AVIATION...MOIST WESTERLY FLOW COMBINED WITH RELATIVELY UNSTABLE
CONDITIONS WILL ALLOW FOR SCATTERED SHOWERS IN THE MOUNTAINS THIS
AFTERNOON THROUGH THIS EVENING. SO EXPECT SOME MOUNTAIN
OBSCURATION THROUGH AT LEAST 30/0900Z ACROSS WESTERN MONTANA. SOME
DRIER AIR WILL WORK IN ALOFT LATE TONIGHT AND THIS COMBINED WITH
LIGHT SURFACE WINDS WILL HELP FOG TO DEVELOP ESPECIALLY KMSO AND
KGPI. THE FOG WILL DISSIPATE BY MID-MORNING THURSDAY. FOR THE MOST
PART MOST VALLEYS WILL BE RATHER STABLE ON THURSDAY WHILE THERE
WILL BE AN INCREASING CHANCE FOR RAIN SHOWERS ACROSS LINCOLN
COUNTY, MONTANA (TROY/YAAK AREAS) BY EVENING.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&

$$





000
FXUS65 KMSO 291101
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
501 AM MDT WED OCT 29 2014

...WIDESPREAD SNOW TO IMPACT NORTHERN ROCKIES THIS WEEKEND...

.DISCUSSION...

Low elevation rain and high elevation snow showers will slowly
diminish across the Northern Rockies throughout today. Snow levels
as low as 6500 feet are anticipated, particularly during this
morning. Mountain passes above 6500 feet, such as Lost Trail,
Bannock, Lemhi passes, will be impacted by light snow
accumulations and some brief hazardous driving conditions during
this time.

This evening through Thursday, mainly dry and relatively cool
conditions will be present across the Northern Rockies, as high
pressure briefly returns to the region. Daytime temperatures will
warm a bit between today and Thursday, however warming will be
muted for low and middle elevation valleys by high cloudiness.
Some valleys will experience persistent temperature inversions day
and night in this weather scenario.

...BIG SNOW EVENT POSSIBLE THIS COMING WEEKEND...

The high pressure will slowly erode across the Northern Rockies on
Friday, ahead of a significant snow-producing low pressure
circulation this weekend. Model guidances are beginning to
coalesce around a low pressure trajectory from the Snake River
Plain near Boise, Idaho, northeastward over west central Montana
from Saturday evening through Sunday afternoon. This low pressure
circulation is likely to be accompanied by plenty of Pacific
moisture, as well as plenty of cold air, as it moves across the
Northern Rockies. Snow accumulations on roadways are probable for
elevations above 4500 feet from the Clearwater Mountains of
Idaho, eastward toward the Butte/Blackfoot Region. Population
centers, such as Butte, Deer Lodge, Anaconda, and Georgetown Lake,
should brace for a snowy weekend. Hazardous driving conditions
due to slick roadways and periods of low visibility in snowfall
are becoming increasingly likely across the region. Most mountain
passes are anticipated to receive a snow impact, generally
accumulating 3 to 6 inches Saturday night through Sunday midday.

The main low pressure circulation will continue east of the
Continental Divide by Sunday night, with rain/snow showers slowly
diminishing over the Northern Rockies thereafter. Some models
suggest that active fall weather will continue to be present
through at least the middle of next week, however their
reliability on timing storm systems is fairly low at this time.
Therefore, probability of precipitation closely reflects that of
climatology following the weekend low pressure event.

&&

.AVIATION...Scattered rain showers will continue to obscure area
terrain and reduce visibilities through this morning. Shower
activity is expected to decrease by the afternoon, but a few light
showers may linger around northwest Montana. A drier airmass will
move in this evening leading to clearer skies and possibly fog
development at KGPI and KMSO. KGPI will have the best chance to
see fog development on Thursday morning and may impact travel.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

Zumpfe
Aviation...Kino

$$






000
FXUS65 KMSO 282030
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
230 PM MDT TUE OCT 28 2014

...Strong Cold Front this weekend...

.DISCUSSION...A moist weather system will shift across north
central Idaho and western Montana this evening and tonight. Most
areas (from Orofino and Grangeville eastward across Libby,
Kalispell, Eureka, Saint Ignatius, Missoula, and Hamilton)...valleys
and mountains...should see significant showers. The exception may
be Lemhi County due to the main moisture feed remaining just to
the north. The air mass should cool enough to lower snow levels
down to 5500 to 6000 feet overnight. Skalkaho and Lost Trail
Passes should be the most susceptible to snow showers and
possible slick roads.

A drier westerly flow should take hold Wednesday and Wednesday
night. Partial clearing Wednesday night may allow some valley fog
to develop by Thursday morning.

A very weak warm front is expected to shift northward across the
area Thursday...but mainly just produce clouds.

Forecast confidence is high for a big change to cooler and wetter
weather this weekend, however, models are still having difficulty
with the placement of the heaviest precipitation. Models have been
consistent in showing impacts for Lemhi county Friday night and
Saturday. The ECMWF model recently trended farther east and faster
with the upper level low and heaviest precipitation, calling into
question how bad the impacts will be for Georgetown Lake and
Butte. Regardless, models agree on some precipitation which will
fall as snow above 4000 to 5000 feet. Some expected impacts and
their confidence are listed below.

Lemhi County: Rain Friday night turning to snow will impact
highways 93 and 28, especially Lost Trail Pass, Gilmore Summit,
and Lone Pine. Salmon may receive some light snow showers Saturday
night and Sunday morning.

Southern Bitterroot mountains: Skalkaho and Lost Trail passes may
receive several inches of snow. Confidence decreases on snow
amounts farther north, though some mountain snow is likely.

Butte, Anaconda, and Georgetown Lake areas: Some snow is likely,
but recent model trends cast doubt on the amounts. There is
potential for several inches of snow affecting areas above 4000
feet, and especially above 5000 feet Saturday. Homestake and
McDonald passes may see very difficult driving conditions this
Saturday.

Rest of Western Montana: Rain and a few inches of mountain snow
is likely with impacts for Lolo and Lookout passes. Mainly rain is
expected in the valleys with light snow showers possible Sunday.

In the long term...models are inconsistent regarding timing of
weather systems and the exact location of the main storm track.
However, the pattern seems to be fairly moist within most model
solutions. As such, we have increased the precipitation forecast
for early next week as well.

&&

.AVIATION...A moist frontal system will move over north central
Idaho and western Montana this evening and tonight. Showers will
be on the increase with the lower air mass slowly saturating as
well. Increasing mountain obscurations should occur with
occasional lower visibilities in the valleys with showers as
well. KGPI and KMSO will be most susceptible to the showers this
evening and then KBTM by later tonight.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$






000
FXUS65 KMSO 281103
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
503 AM MDT TUE OCT 28 2014

...ACCUMULATING SNOW TO SIGNIFICANTLY IMPACT SOUTHWEST MONTANA
AND AREA MOUNTAIN PASSES SATURDAY THROUGH SUNDAY...

.DISCUSSION...

A fast moving Pacific storm system is anticipated to sink
southward over the Northern Rockies from today through Wednesday,
bringing mainly rain and relatively cool temperatures to the
region. The mountains of northwest Montana and northern Clearwater
mountains in Idaho will likely receive the most impressive
precipitation amounts, around 0.50" total.

Conditions dry once again Wednesday night through Thursday, as
high pressure redevelops over the Northern Rockies. Daytime
temperatures will warm during this time, concurrent with a slow
increase in high cloudiness over time.

Winds will increase over high terrain and across high valleys
beginning Friday afternoon, as a vigorous low pressure circulation
moves from the Great Basin northeastward toward southwest
Montana. The most recent iteration of the European model suggests
that the low pressure will intensify over Yellowstone Park,
drawing cold air and precipitation eastward along the Continental
Divide, as well as the Butte/Blackfoot region. Snow levels are
likely to drop rapidly throughout Saturday, with snow accumulating
down to 4500 feet. Mountain passes, such as Homestake, Lost Trail,
and MacDonald, may receive 6-12" snow and experience visibility
down to several hundred feet at times Saturday evening through
Sunday midday. Population centers, such as Butte and Anaconda,
may receive some snow accumulations during this time, impacting
area travel with slick conditions for the first time this cold
season. These hazardous driving conditions appear increasingly
likely Saturday through Sunday.

Model guidances suggest that an active pattern will continue to be
present across the Northern Rockies through early next week. The
pattern depicted by current model iterations shows a pattern that
suggests little change from recent conditions. Thus, probability
of precipitation above that of climatology appears to be an
appropriate forecast at this time.

&&

.AVIATION...High clouds will be moving in this morning which
should help clear out any fog that has developed overnight. The
next weather system will move into northwest Montana this
afternoon bringing rain to KGPI. Main impacts will be low
ceilings, mountain obscurations and periodic reductions in
visibility. KMSO should see showers starting to move in after
29/0000Z. All other TAF sites may see a few rain showers which
could lower ceilings briefly.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

Zumpfe
Aviation...Kino

$$






000
FXUS65 KMSO 272011
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
211 PM MDT MON OCT 27 2014

...COLD FRONT AND BIG COOL DOWN THIS WEEKEND...

.DISCUSSION...Although the flow aloft is slowly drying, low level
instability and orographic (mountain) lift will maintain rain and
graupel showers primarily over west central and southwest Montana
through late afternoon. Otherwise, high pressure will build
through the night, allowing skies to clear and better cooling to
take place. This could lead to some valley fog in the very early
morning hours.

A fast moving disturbance will spread cloud cover over the
Northern Rockies Tuesday morning, with rain and high mountain snow
shortly behind, increasing mainly through Tuesday afternoon and
evening. Temperatures look pretty mild with this feature, and thus
sticking snow should be well above pass levels.  Winds aloft will
increase through the day Tuesday due to an accompanying westerly
jet. Expect breezy conditions Tuesday afternoon through Wednesday in
the mountains, and higher west to east oriented valleys.

It will be a close call for precipitation on Friday. In central
Idaho, towns like Grangeville and Orofino will likely have rain
before trick-or-treating begins. The situation will be the same in
far Northwest Montana for Troy and Libby. Farther east Kalispell,
Missoula, and most of the Bitterroot Valley may see some rain
before the trick-or-treating ends, and will likely see rain before
midnight. Further east and south still, locations such as Salmon,
Butte, Anaconda, and Deer Lodge will be dry through the evening
festivities.

Saturday the cold front moves across the region causing snow
levels to fall through the day Saturday with much cooler
temperatures by Sunday and Monday morning. Despite the big cool
down the temperatures will only be average or slightly below
average for this time of year.

&&

.AVIATION...Invading drying air will allow skies to clear
overnight. This could lead to some shallow valley fog after
midnight, but it is not expected to be a major impact to the
airports. The next system will spread high and mid clouds in from
the west through the day Tuesday. Late Tuesday afternoon through
early Wednesday night will be the period most likely to have
lowered ceilings and minor visibility reductions. Mountain winds
and obscurations will be widespread.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$






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