Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 232045

Area Forecast Discussion
National Weather Service Missoula MT
245 PM MDT Mon Apr 23 2018

.DISCUSSION...Warmer temperatures are expected this week. This
should translate into the first 70+ readings of the spring for
many valleys by Tuesday, Wednesday and Thursday...and then a few
lower valleys reaching 80 or a few degrees higher by Friday.

There is a fast moving and weak weather disturbance that is
expected to brush western Montana Wednesday. This disturbance
should produce scattered light precipitation especially along the
Continental Divide and additional cloud cover across the
remainder of western Montana Wednesday. This will also cause a
temporary down tick in the temperatures across western Montana

The much warmer temperatures this week will cause an increase in
snow melt and significant stream and river rises into next weekend
across north central Idaho and Western Montana. Many of bigger
rivers (Clearwater, Bitteroot, Flathead, Yaak, Fisher, to name a
few) may rise 2 to 5 feet (please see stream forecasts for each
river for exact amount) by Sunday...compared to current levels.
Although no significant flooding is expected...these significant
stream rises will translate into much higher and potentially
dangerous stream flows and a huge difference by this next weekend
for those that regularly access the area rivers/streams.

The next significant weather system appears due Saturday and
Sunday, but with a lot of uncertainty regarding amount of
precipitation and timing. The operational GFS model is very wet
for the northern Rockies and appears to be more of an outlier at
present time. The ECMWF and Canadian models are slower moving
this moist system into the northern Rockies and with less
precipitation through Saturday. We are keeping significant showers
in the forecast by Saturday and Sunday, but not hitting it too
hard with amounts. Stay tuned since the amount of precipitation
could be important to how high streams/rivers eventually rise.


.AVIATION...The moist low pressure system that has produced
widespread showers and mountain obscurations in southwest Montana
Monday will exit with conditions improving overnight. Elsewhere
across northwest Montana and north central Idaho, skies should
clear this evening as high pressure builds over the region.



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