Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 261011

Area Forecast Discussion
National Weather Service Pocatello ID
311 AM MST Sun Feb 26 2017

.SHORT TERM...Today through Tuesday night. An area of low pressure
currently located off of the Washington and British Columbia
coast will evolve into a seasonally-strong trough which will swing
through our area on Monday. As a result, snow showers are
expected to develop across the Sawtooths and Wood River Valley by
late this afternoon, as well as across the Continental
Divide/Island Park area. As we head through the night tonight,
snow showers are expected to develop across all of SE Idaho. The
heaviest snow is expected for the Sawtooths this evening and for
the Upper Snake Highlands/Continental Divide areas Monday morning.
Winds will be on the increase as well, strongest across the
Sawtooths overnight with the strongest winds transitioning to the
Snake Plain and Southern and Eastern Highlands on Monday. Have
issued a Winter Weather Advisory beginning at 5PM MST this evening
for the Sawtooths/Wood River Valley and for the Upper Snake
Highlands/Divide/Island Park area. Anticipate roads to become
snow-covered and slick after sunset, and along with areas of
blowing snow will create a difficult morning commute. Considered
adding other areas to the Advisory as well, namely the I-15
corridor and Eastern Highlands. Some forecast guidance indicates
the potential for a burst of snow along the I-15 corridor from
roughly 3- 7AM Monday, which would mean slick conditions for I-15
and Pocatello and Idaho Falls. Given uncertainty on placement of
this band, will hold off on issuance here for now. There is also
some uncertainty on the timing and intensity of the heaviest snow
over the Eastern Highlands as well, so will also hold off on
issuance for these areas. Nonetheless, difficult Monday morning
commute may result here as well.

Expect a break in the snowfall for many areas (Divide region
excepted) Monday evening before the next wave of snow showers
develops across the Sawtooths Monday night and Tuesday morning, and
for the Eastern Highlands by Tuesday afternoon. Snow amounts are
currently forecast to be lighter than the first wave, but will act
to prolong the presence of snow-covered roadways. Tuesday afternoon
looks particularly breezy across the Snake Plain as well, with SW
winds 15-25 mph with gusts approaching 40 mph. This may result in
difficult travel for high profile vehicles. May see areas of blowing
snow for passes as well Tuesday. AD/RS

.LONG TERM...Wednesday and Saturday west to northwesterly flow aloft
prevails with moist conditions favoring the westerly slopes of the
Central Mountains and the Eastern Highlands. The GFS model brings an
embedded disturbance through the Upper Snake Highlands Wednesday
afternoon/evening that will serve to focus a 1 to 3 inch snow event
from about Wayan north to Macks Inn. The Island Park area remains in
the moist flow into early Thursday, thus snow amounts up to 4 inches
are possible in that area. Models do favor activity picking up by
Sunday and Monday of next week. For the Eastern Magic Valley and
Lower Snake Plain, afternoon high temperatures warm back into the
lower 40s. RS


.AVIATION...Expect VFR conditions through Sunday afternoon. Snow is
expected to return to KSUN about 01Z this evening, and KBYI and KIDA
near 27/06Z, KPIH near 27/08Z. These should be limited to about 2 to
3 hour events associated with a passing frontal band. Breezy SW
winds 15-25G35 mph Monday afternoon in the Snake Plain. RS


.HYDROLOGY...After coord with county EM`s, have trimmed back all
hydro warnings and advisories for the Upper Snake River Plain and
Southern Highlands due to cooler temperatures now and expected to
continue through early next week. Eastern Magic Valley is still have
issues with water ponding and we have continued all the Areal Flood
Warnings in that area. Next warm up comes late next week. Huston


Winter Weather Advisory from 5 PM this afternoon to 5 PM MST
Monday for IDZ018-019-031.


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