Area Forecast Discussion
Issued by NWS Boise, ID

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FXUS65 KBOI 210314

Area Forecast Discussion
National Weather Service Boise ID
914 PM MDT Wed Sep 20 2017

.DISCUSSION...Shower coverage has decreased across most of SE
Oregon and SW Idaho this evening, along with an end to the
isolated thunderstorms. Will update for lower pops and remove
mention of evening thunderstorms in these areas. The exception is
a wide swath of showers which extends from SW to NE (to the
northwest of a cold front) across northern NV and into S-Central
Idaho. This area will receive widespread showers through the night
where pops and QPF amounts will be raised for the remainder of
tonight. The showers will continue through Thursday as an upper
trough settles into the region, with the bulk of the showers
expected near the Nevada border. Light snow accumulations will
continue in the higher elevations mainly above 6000 feet. Temps
will remain cool on Thursday with valley highs only in the 50s.


.AVIATION...generally low VFR. MVFR in rain showers near KTWF and
KJER overnight. Mountains obscured at times. Isolated showers
developing over mountains during Thu afternoon. Surface winds
generally NW 5-15kt. Winds aloft at 10kft MSL: northerly 5-10kt.


SHORT TERM...Tonight through Friday...The cold front should
generally push through the area by this evening, with cooler
conditions expected. Showers to continue across the area tonight,
with the Western Magic Valley looking to be the most favorable
area for activity tonight. Meanwhile, residual moisture from the
system will leave the threat for showers through the next couple
of days as the trough closes off to become an area of low
pressure. As the low sits around the ID/OR border on Thursday, we
can expect lighter wind. Models then showing the low moving east
on Friday, with wraparound moisture expected into central Idaho to
keep showers present. Temperatures will remain 15-20 degrees
below normal through at least Friday.

LONG TERM...Friday night through Wednesday...Upper level trough
axis will be just to the east of the CWA by Saturday, which will
dry out conditions in the northerly flow. A slight chance of
showers exists Saturday afternoon in the Idaho Central Mountains
with lingering moisture. As a ridge builds off the coast, the
northerly flow will continue with a shortwave or two coming down
the divide, bringing nothing more than cloud cover to the area
through Monday. For Tuesday and beyond, the ridge will continue to
move east, until it is directly overhead by midweek. Temperatures
will be steadily increasing each day, to near normal by early to
mid next week.





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