Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 050950

Area Forecast Discussion
National Weather Service Missoula MT
350 AM MDT THU MAY 5 2016

...Thunderstorms this Afternoon...
...Increasing Winds Early Friday through Saturday...

.DISCUSSION...An approaching frontal system is bringing showers
and isolated thunderstorms through north-central Idaho and
northwest Montana this morning. These showers will continue to
spread north-northeast through the morning. By early afternoon,
daytime heating will increase the instability over the area, and
another round of showers and thunderstorms are expected to develop
and last through the evening hours. Storms could become scattered
to numerous, and bring gusty winds and frequent lightning. Brief
heavy rain and hail are also possible in stronger storms. These
storms are likely to disrupt outdoor plans. Those that see/hear
thunderstorms should plan to take shelter.

The focus of showers and thunderstorms will shift southward for
Friday and Saturday, resulting in lingering precipitation for
north-central Idaho and southwest Montana during this time. In
addition, a strong pressure gradient will strengthen over the area
due to a cool, surface high pressure east of the Continental
Divide. Therefore, east winds will increase across northwest
Montana early Friday morning, and strengthen across the rest of
western Montana and into Lemhi County by Friday afternoon. These
breezy winds can disrupt boating activities on area lakes,
especially Flathead Lake, as choppy conditions grow. Exposed
north-south roadways could experience strong crosswinds at times.
Winds will decrease by Saturday.

The models are indicating another low pressure system move down
out British Columbia on Sunday night into Monday. This low
pressure system will bring another round of widespread
precipitation and cooler temperatures. Maximum temperatures on
Monday appear to be running around 5 degrees below normal for this
time of year.

The low is anticipated to slowly progress across southern Idaho
into Wyoming Tuesday into Wednesday. The position of the low will
cause wrap around precipitation which will mainly impact the
Continental Divide down into southwest Montana. Temperatures will
remain below normal on Tuesday with a slight warming on Wednesday.
The models diverge on a solution for the latter part of the week,
so little changes were made to the current forecast.


.AVIATION...Showers with isolated thunderstorms are streaming
through north-central Idaho and northwest Montana this morning,
with light showers in the vicinity of KGPI. Another round of
showers and thunderstorms will develop across the area around
05/2100Z and last through the evening, bringing a thunderstorm
chances to KGPI, KMSO, and KBTM. The primary threat with stronger
storms will be gusty winds and frequent lightning, with periods of
brief heavy rain and hail possible. Stronger showers will also
quickly lower ceilings, briefly obstructing terrain and
visibility. An increase in easterly winds will begin for KGPI and
KBTM after 06/0400Z, and KMSO generally after 06/0600Z.



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