Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 210845

Area Forecast Discussion
National Weather Service Glasgow MT
245 AM MDT Mon Oct 21 2019


Synoptic Setup: Forecast begins with a large trough over the
central Part of Canada and the CONUS. A large ridge is beginning
to develop up the west coast from California to central British
Columbia. Farther west another trough/ridge couplet lies over
the north Pacific.

Today through Tonight: Northwest flow will bring dry and warm
conditions with a weak mesoscale ridge arriving overnight.

Tuesday to Wednesday: By Tuesday afternoon the ridge will exit
and the trough portion of the couplet will move through dropping
temperatures and working with the extra moisture int eh flow to
generated scattered showers. Afternoon rain showers could
transition to snow across the far northeast after midnight with
the arrival of a cold front. By Wednesday the cold will settle in
and remnant moisture will lead to further diminished showers.
Total amounts look to be less than a quarter of an inch with
maybe a half of snow for actions that get cold enough.

Wednesday night to friday night: Larger pacific ridge will arrive
during this time drying things out and raising temperatures to
highs in the 60s by Friday. Meanwhile, the trough part of the
couplet will be on its heels.

Saturday onward: The trough part of the pacific couplet will
arrive. Along with it should be initial rain/snow showers and
strong winds followed by much colder air lasting into early next
week. Confidence about how long the cold air will stay around is
in question.




DISCUSSION: Isolated showers with mostly virga will pass across
the area early this morning. By the late mrning into the overnight
conditions will clear. Beyond the TAF cycle a weather system is
expected to arrive Tuesday evening with a mix of light rain/snow
and maybe MVFR conditions.

WINDS: Light and variable through the morning becoming west in
the afternoon around or less than 10 kts.





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