Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 252022

Area Forecast Discussion
National Weather Service Missoula MT
222 PM MDT Sat Mar 25 2017

.DISCUSSION...Scattered showers will continue across the Northern
Rockies this afternoon as a relatively cool trough of low
pressure quickly moves through the region. Precipitation will
likely fall as a rain/snow mix over the higher mountain passes
during the day, but given the warm spring sun and warm ground
temperatures, impacts to travel are not expected. Showers will
decrease in intensity and coverage after sunset. By Sunday
morning, a ridge of high pressure aloft will set valleys up for
some patchy morning fog. Lingering cloud cover and the ridge axis
still to our west make the setup less than ideal for fog
formation, but recent moisture should be enough to cause boundary
layer saturation in many valleys. Any fog that forms should
dissipate quickly after sunrise.

A weak disturbance is still forecast to move through the Northern
Rockies on Monday through Tuesday morning, introducing scattered
rain showers and breezy winds across the area. Some mountain
passes could see light snowfall as cooler air tracks through the
region, but minimal impacts are expected at this time.

Brief warming and drying will return later Tuesday into Wednesday
before another disturbance approaches the area late Wednesday
into Friday. Shower activity will increase in coverage, and snow
levels will lower to allow periods of mountain and mountain pass
snow. However, forecast confidence remains low due to model trends
digging this low pressure system farther south, resulting in
decreased precipitation chances for the Northern Rockies.


.AVIATION...Scattered rain showers may wet runways at times this
afternoon, with brief reductions in visibility, on the order of 10
to 15 minutes each. Winds will likely be breezy below showers,
gusting to around 20 kts. Showers decrease quickly after sunset.
After 26/0600z, patchy fog will likely develop in valleys. Not all
aviation models agree on fog formation, and not all the
ingredients for a widespread fog morning are present, so
confidence is only moderate that fog will impact TAF sites. Fog
that does form is not expected to be thick, and should quickly
dissipate with morning heating from the sun.



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