Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 262135

Area Forecast Discussion
National Weather Service Missoula MT
235 PM MST MON JAN 26 2015

.DISCUSSION...Thick fog and a low stratus layer have affected
some places in central Idaho and western Montana, while other
locations have remained clear and sunny all day. Needless to say,
fog development has been tricky to forecast. It will stay tricky
to try and pin down who will see fog Tuesday and/or Wednesday
mornings, but it does appear that Kalispell, Salmon, and locations
along the I-90 corridor, including Missoula, have the best chances
for fog development tonight into Tuesday morning.

In addition, more record-breaking warmth is expected in select
locations (Hamilton, Butte, Drummond, etc) and could extend for
yet another day Tuesday. These anomalously warm valley
temperatures, including equally warm values in the mountains, are
a direct result of the persistent, strong area of high pressure
locked over the western United States.

That being said, a surge of moisture from the south will brush
Lemhi County and southwest Montana Tuesday night into Wednesday. At
the same time, a weak shortwave trough will swing through from
the northwest. The result will be light precipitation that will
move through the region, with best chances occurring over Lemhi
County and southwest Montana region. The valleys of Lemhi County
may see a slight chance of freezing rain Tuesday night/early
Wednesday morning, which could create slippery conditions for
roadways, particularly along Highway 93 south of Lost Trail Pass.

While mostly dry and sunny conditions will exist Thursday/Friday,
the next chance of precipitation could occur next weekend, as the
warmer high pressure finally shifts enough to allow colder
northwest flow to move over western Montana. Unfortunately, long-
range models still wobble on the amount of cold air that will
return to the region and how much precipitation that could return
with it, so the impact details are unknown at the time. In other
news, a much wetter weather pattern is looking more likely by
early next week.


Some breezy southerly winds of 15-25 kts are occurring today over
the higher terrain, including some downslope winds along the
Continental Divide through today. Fog will remain an issue for
KSMN through the early afternoon before lifting out of the area
early this evening. Continued high pressure and relatively clear
conditions over the region will allow cool, stable conditions to
return to the valleys tonight and allow fog to redevelop overnight
after midnight for KGPI and KSMN, and for KMSO before sunrise. Fog
issues are likely to mix out by mid morning.



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