Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 212018

Area Forecast Discussion
National Weather Service Missoula MT
218 PM MDT Mon Aug 21 2017

.DISCUSSION...High pressure will build over the northern Rockies
and produce dry and warmer conditions Tuesday and much of
Wednesday. The lower atmosphere will be quite stable with
relatively poor mixing of valley smoke. However, a more easterly
low level pressure gradient may temporarily force some of the
smoke more westward tonight into Tuesday.

An approaching trough of low pressure is expected to produce a
more southwest flow late Wednesday and direct some mid and high
level moisture over north central Idaho and western Montana. The
atmosphere should become unstable enough to support a few late day
light rain showers or thunderstorms over Idaho...possibly shifting
into western Montana Wednesday evening and night. Initially, the
showers will probably produce more in the way of gusty winds than

The air mass over west central and southwest Montana should
continue to moisten a little into Thursday making Thursday
afternoon the best potential for a few thunderstorms. A few storms
may produce pockets of wetting rain. However, most areas are not
expected to see much precipitation. A cold front will also shift
across the area and increase the west to northwest winds with
quite breezy conditions across western Montana Thursday. The
impact to area wildfires and choppy wave conditions on area lakes
will be the primary concern.

In the longer term, high pressure and the very warm, stable and
dry air mass is expected to return late Friday and over the


.AVIATION...Stable conditions under strengthening high pressure
will occur into Tuesday. Reduced visibility resulting from
settling wildfire smoke will impact KBTM and KMSO into tonight,
and to a lesser extent KSMN and KGPI.



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