Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 151953

Area Forecast Discussion
National Weather Service Pocatello ID
153 PM MDT Sun Apr 15 2018

.SHORT TERM...Tonight through Tuesday night. Shortwave has slipped
past East Idaho early today, leaving dry slot across the region.
Next shortwave pushing into Oregon this afternoon poised to spread
moisture into the central mountains beginning this evening.
Pacific low continues to shift towards coast, deepening southerly
flow. This has a dual effect of keeping precip confined mainly to
the central mountains overnight and increasing the southerly
surface winds across the southeast corner of the region in
response to steepening surface low to the west. There is some weak
instability so have left slight chance thunder mention for the
early evening. Cold front drives across East Idaho late tonight
through early morning. Precip shifts east behind the front with
snow levels dropping toward valley floors. Main band of
precipitation moves through the Snake Plain into the highlands
east of I-15 during the afternoon and evening. There is a brief
band of instability associated with the front, but much more
stable air immediately behind the front should preclude any
significant convective development thus kept thunder out of the
forecast. Overall snow amounts remain low from valley floors up to
pass level, with the most significant amounts well above 7000 ft.
There is a concern regarding the wind speeds but guidance
averaging just below advisory criteria so kept headlines out of
consideration for now. Upper trough begins pushing through late
Monday night into Tuesday. Weak instability returns, but it
doesn`t appear to be enough to force deeper convection so again
left thunder out. Tuesday however should be much windier with more
favorable winds aloft. Guidance nowhere near consensus though so
still holding off on headlines. DMH

.LONG TERM...Wednesday through next Sunday. The middle of the week
begins under building high pressure from the south and west. Low
pressure situated off the west coast of California will begin to
work moisture into Central Idaho by the evening and may bring snow
showers to the mountain tops. This moisture will spread to the rest
of the state through Thursday bringing chances of rain and snow. The
amount of influence of the moisture is still a bit uncertain, and
will be dependent on where the low decides to track next week. It
is set to progress through the four corners region to our south,
with wrap-around moisture for us. It will also be a bit breezy
Thursday with winds out of the north and northeast due to the
position of the low. Things should clear out by Friday with maybe
some lingering snow showers in the Bear Lake area Friday only.
Saturday looks very nice indeed with high pressure in place and
temperatures in the 60s. Sunday is much of the same though some
showers may work into Central Idaho. What a pleasant weekend in
store! NP/DMH


.AVIATION...Generally VFR CIGS and VIS expected for all sites this
forecast period with a mention of TS or SH possible this evening
through the night at SUN. Winds will flow generally above 12 knots
in the 15+kt range this evening prior to sunset then improve
overnight with the exception of PIH. Downslope winds will kick in
and still blow at 15 to 20 knots or so overnight. Winds will again
increase in the 10 to 15+kt range tomorrow afternoon. NP/DMH



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