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000
FXUS65 KMSO 111041
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
441 AM MDT Tue Mar 11 2014

...LOCALLY DENSE VALLEY FOG THIS MORNING...AND AGAIN TONIGHT...

.DISCUSSION...

Aside from periods of snow across southwest Montana and along the
Continental Divide this morning that are creating some hazardous
travel conditions above 5000 feet, high pressure will become the
dominant weather feature across the Northern Rockies during the
next several days. Residual moisture from recent rain and snow
will allow patchy, locally dense fog to develop within area valleys
this morning and again tonight through Wednesday morning. The
clearing skies tonight will likely increase the coverage and
severity of the fog. Otherwise, mainly dry and relatively mild
conditions will prevail through Thursday. Some of the model
guidance suggests that a weak storm system will move over
northwest Montana on Thursday morning, however this particular
system appears to be of little consequence.

The next noteworthy storm system will likely arrive over the
Northern Rockies Friday through midday Saturday. Precipitation
appears to be widespread with this particular system, however
models appear to weaken key features associated with this system
as it moves inland from the Pacific Ocean. The ridge of high
pressure present for much of the next week appears to be culprit
of such system weakening, with the high pressure quickly
rebounding beginning on Saturday. Just the same, snow levels will
likely be near mountain pass elevations, with minor snow
accumulations to create some hazardous driving conditions.
Otherwise, rainy and cold will be rule for most populated areas
below 4500 feet.

Similar to previous extended forecast period discussion, model
guidance appear to depict the weather pattern over the Northern
Rockies vacillating between low and high pressure ever 2 to 3
days Saturday through the end of the next week. The so-called
progressive weather pattern will translate to relatively large
day-to-day changes in weather, from sunny and warm one day to
rainy and cold the next. You get the picture: more Spring, less
snow.

&&

.AVIATION...

Periodic snow will continue to exist, mainly across southwest
Montana, through 11/1800Z. KBTM will experience decreased ceiling
and visibility at times in light snow. Terrain will be most
obscured across southwest Montana through 12/0000Z. Occasional
terrain obscurations will be present elsewhere. KGPI has
experienced and will continue to experience fog through 11/1600Z.
Fog will redevelop for KGPI and KMSO after 12/0600Z and likely be
present through 12/1600Z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY until 9 AM MDT this morning ABOVE 5000
     FEET FOR THE Bitterroot/Sapphire Mountains.

     WINTER WEATHER ADVISORY until 9 AM MDT this morning ABOVE 5000
     FEET FOR THE Butte/Blackfoot Region.

ID...WINTER WEATHER ADVISORY until 8 AM PDT this morning Lower Hells
     Canyon/Salmon River Region...Orofino/Grangeville Region.

     WINTER WEATHER ADVISORY until 8 AM PDT this morning ABOVE 5000
     FEET FOR THE Southern Clearwater Mountains.

&&

$$

Zumpfe

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