880
FXUS65 KMSO 092009
AFDMSO

Area Forecast Discussion
National Weather Service Missoula MT
209 PM MDT Sun Jun 9 2024

.DISCUSSION...A weak disturbance is moving into Lemhi county and
southwest Montana this afternoon which will cause scattered
showers and thunderstorms. A few of these storms could become
quite strong with the potential of gusty and erratic winds as
there is fairly significant dry layer near the surface. Once the
moisture increases in the low levels, moderate to heavy rain will
be the issue with these storms.

A cold front tracks across Northern Rockies tonight, which brings
widespread precipitation. The probability of at least of tenth of
an inch of rainfall increases dramatically east of line from
Kalispell to Lowell with highest chances (70-90%) being across
Lemhi county and southwest Montana. While north-central Idaho and
extreme northwest Montana appears to get missed by the bulk of
the precipitation this time.

A disturbance is expected to slide along the Canadian border
on Tuesday causing the pressure gradient to tighten over the
Northern Rockies. This pressure gradient will create gusty
westerly winds Tuesday across west central and northwest Montana.
Then the focus of the winds shift to Lemhi county and southwest
Montana on Wednesday. Hwy 93 from Kalispell to Missoula has a 40
to 70% chance of receiving wind gusts in excess of 30 mph on
Tuesday afternoon. The crest of the Mission and Swan ranges along
with the Continental Divide around Glacier NP has a 50-70% chance
of wind gusts greater than 50 mph. On Wednesday afternoon, I-90
from Garrison Junction to Butte along with Lemhi county has a
50-80% chance of having gusts over 30 mph.

A ridge of high pressure builds back over the Northern Rockies on
Thursday into Friday causing a warming and drying trend. Over 90%
of the models are indicating a trough of low pressure moving into
the region this weekend bringing an increase in the potential of
precipitation and cooler temperatures.



&&

.AVIATION...A shortwave will continue to cause thunderstorms
across Lemhi county into southwest Montana this afternoon into the
early evening hours. KSMN and KBTM will be mainly impacted by this
feature, as storms will be capable of gusty erratic winds at first
then transition over to moderate to heavy rain producers. The
threat of this first round of storms at KSMN and KBTM should
diminish around 10/02z. Then a cold front tracks across the
Northern Rockies tonight causing widespread precipitation. The
precipitation associated with this front should start to impact
KGPI, KMSO, KHRF and KSMN around 10/04z, then KBTM around 10/06z.
The front should pass through the Northern Rockies by 10/12z.


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

$$