Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 220933

Area Forecast Discussion
National Weather Service Missoula MT
333 AM MDT Sun Apr 22 2018

.DISCUSSION...Today will start out as another nice, warm spring
day in the northern Rockies. A trough is currently moving on shore
over the Washington coast and heading our direction. There isn`t
much moisture for this trough to work with, so for most of the
area just expect an increase in cloud cover today. Tonight as the
trough moves east of the Continental Divide it will develop into a
closed low pressure system and start to tap into some of the
moisture east of the Continental Divide. Moisture will wrap around
the low and cause rain and snow showers this evening. Lemhi
County, Idaho and southwest Montana will be most affected by this
system. MacDonald, Homestake, and Lost Trail passes will see some
new snow tonight with new snow in Butte as well by Monday morning.

The impacts from this snow are uncertain as it will be mixed with
rain part of the time, and recent warm temperatures have warmed
the ground and roads. Available road surface models indicate that
the current forecasted snow amounts will melt on the road causing
slushy conditions at times. Enough snow to cause roads to become
icy is still possible, but is not expected.

After a chilly start with temperatures in the 20s and 30s on Tuesday,
several locations will have a chance of cracking 70 degrees.
Expect plenty of sunshine most areas with high temperatures
warming to around 10 degrees above normal.

Wednesday through Friday will continue the mild trend with
summer-like warmth during the day, but freezing or sub-freezing
temperatures at night. This will be a week
where those with sensitive plants will definitely need to take
measures to cover or bring them inside at night. There is a chance
that some locations could hit 80 degrees by the week`s end.

The ridge begins to break down a little bit by next weekend which
will bring a chance for showers and thunderstorms into the


.AVIATION...Mostly clear skies this morning with increasing clouds
today. The approaching trough does not have much moisture to work
with and is expected to be rather lackluster until it starts to
spin up east of the Continental Divide. Then wrap around moisture
will cause rain and snow showers tonight mainly after 23/02Z and
only affecting terminals KBTM and KSMN. Other area terminals will
only see an increase in cloud cover.



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