Area Forecast Discussion
Issued by NWS Missoula, MT

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FXUS65 KMSO 190921

Area Forecast Discussion
National Weather Service Missoula MT
321 AM MDT Tue Jun 19 2018

.DISCUSSION...The low pressure system that brought rain to much
of the Northern Rockies Monday continues to rotate east of the
Divide, bringing additional rainfall amounts to the region. Though
amounts today will be much less than Monday, today will still be
cool, dreary, and damp for the general region. Because of the
continuous light to moderate rainfall, small streams and creeks
are running higher and faster than usual. Standing water over
roadways will also be common, at least until rain ends and things
can dry out a bit.

That being said, it does appear that Wednesday will be much
improved over the past few days, with a drier day in store for
north central Idaho and western Montana. Temperatures will remain
cooler than normal across the board, but all things considered:
Wednesday will be a much drier day for our region.

Thursday looks like another very active day. A shortwave trough
moves through the region, providing the instability and trigger
for thunderstorms. In Idaho, the timing of the trough means
daytime heating won`t be able to warm things up and make it as
unstable, so just general thunderstorms are expected early in the
afternoon. Confidence is high for storms south of Missoula and
Seeley Lake in Montana, but not as much for areas north. To the
south, storms look very wet and potentially strong. Northwest
Montana isn`t in as good of a position relative to the trough, so
it will be similar to central Idaho with showers and some general

Next weekend and next week models continue to remain active with
one system after the next, each with a day or two of nice weather
between them. Forecast models have not settled down on the timing
for these systems, so the forecast keeps changing from day to day,
but overall the period will remain active.


.AVIATION...Persistent rainfall will create periodic reductions in
ceilings for most terminals today as the low pressure system spins
just east of the Divide. As precipitation decreases later this
evening and wind speeds die down, fog development will increase.
Depending on how much clearing the region experiences overnight
tonight, Wednesday morning could become quite foggy.



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