Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 282055

Area Forecast Discussion
National Weather Service Missoula MT
255 PM MDT Wed Jun 28 2017

.DISCUSSION...A trough of low pressure remains over the region
today, with a stalled boundary across Lemhi County into southwest
Montana. Showers and thunderstorms will continue to generate along
this boundary through this afternoon. The main threats will be
lightning, brief heavy rain and small hail.

A wave of energy on the back side of the low pressure system will
move south out of Canada into northwest Montana this evening,
shifting into west central Montana overnight. The potential for
showers and some thunderstorms will increase as this feature moves
into the region. The chance of precipitation has been increased to
show this stronger wave than previously forecasted. Showers and
thunderstorms will linger into Thursday, particularly along the
Continental Divide.

High pressure will strengthen over the region Friday into the
weekend. This will lead to a warming trend and overall dry
conditions. As high pressure flattens slightly on Saturday,
breezy afternoon and evening winds will develop. This flattening
will also allow for some afternoon and evening thunderstorm
development, mainly across north central Idaho into southwest

Drier westerly flow will prevail Sunday into early next week,
leading to generally dry, breezy and warm conditions.


.AVIATION...Showers and thunderstorms continue this afternoon
across southwest Montana and central Idaho. Brief heavy rain,
lightning and small hail will be the main threats, with KSMN and
KBTM potentially seeing impacts through roughly 29/0000z. An
approaching wave of energy moving south from Canada will increase
the chances of showers and thunderstorms this evening and
overnight, primarily across western Montana. KGPI will see
potential showers and thunderstorms between 29/0000z and 29/0600z.
KMSO will see the potential for mainly showers developing after
29/0300z and lasting into Thursday morning. Butte will see a
redevelopment of precipitation, most likely after 29/0900z.

Another potential aviation impact this afternoon and evening will
be gusty northwesterly winds. Gusts up to 25 kts are expected,
with KGPI and KMSO likely seeing the higher gusts. In addition,
gusty and erratic winds can be expected in the vicinity of



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