Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 032049

Area Forecast Discussion
National Weather Service Missoula MT
249 PM MDT MON AUG 3 2015

Monsoon moisture is moving into southern Idaho and southwest
Montana this afternoon. As a result, showers and thunderstorms
are beginning to develop as this moisture moves into the region.
Lemhi County Idaho and southwest Montana have the best chance for
thunderstorms this afternoon. These storms are forecast to move
into north central Idaho and western Montana during the evening,
with the main threats being gusty winds and lightning activity.
Another shortwave currently to our west will push a cool front
through the region overnight, so additional showers and a
thunderstorm or two are possible during the night hours. Model
guidance continues to favor north central Idaho into southwest
Montana with the best chance of rain through Tuesday morning, with
only light showers elsewhere.

Tuesday will be cooler with western Montana areas returning to
more seasonal temperatures (the first seasonal-temperature day in
about a week). North central Idaho will also cool a few degrees,
but not as drastically as western Montana. Scattered afternoon
showers and thunderstorms will again be possible over southwest
Montana and portions of central Idaho, mainly southeast of the
Clearwater River drainage in central ID.

On Wednesday, another upper-level disturbance and associated shot
of moisture will bring more widespread showers and thunderstorms
over southwest Montana and north central Idaho. The best chance
looks to be from about a Grangeville ID to Seeley Lake MT line
southeastward. Northwest Montana, meanwhile, looks to remain dry.

A upper-level trough will swing through northern Idaho and
northwest Montana Thursday morning. Without much instability or
moisture, the most likely outcome looks to be light showers or
sprinkles in that area. This trough will increase winds,
especially over ridges in northwest Montana. Without an
associated wetting rain, these winds may pose a fire concern for
that area.

A cool morning can be expected early Friday as a colder and drier
air mass moves in behind the trough. Some of the usually
susceptible valleys will drop into the 30s, and some high-
elevation valleys in northwest Montana could see frost.

Long-range models suggest another surge of moisture over the
Northern Rockies midday Saturday through the remainder of the next
weekend, with showers and thunderstorms possible. Northwest
Montana appears to (once again) be largely missed by this next
opportunity for precipitation over the region.


.AVIATION....Wildfire smoke will continue to cause minor
reductions to visibility through this afternoon. Smoke
concentrations will begin to dissipate during later this evening
as disturbances move into the region. KSMN could see some
vicinity showers and thunderstorms during the afternoon, with
storms spreading north to KBTM by the evening. As a front moves
through overnight into Tuesday morning, KMSO and KGPI will also
have a chance for a couple hours of vicinity showers. Winds will
be gusty with any thunderstorms, and with the frontal passage.



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