High Wind in Idaho, April 2, 2018

Area Forecast Discussion
National Weather Service Pocatello ID
328 AM MDT Mon Apr 2 2018

.SHORT TERM...Today through Wednesday. The big story will be the
strong cold front moving through eastern Idaho today, bringing
cold air, some light snow, and the main issue...STRONG WINDS. We
are seeing winds picking up already ahead of the front, as well as
some light showers in the central mountains and along the Wyoming
border. Of note, for most if not all locations today...HIGHS HAVE
ALREADY OCCURRED or WILL OCCUR THIS MORNING. This storm has a very
strong push of cold air with it, which is lending itself to rain
changing over to snow...including lower elevations before
precipitation ends. This is also lending to strength of the cold
front and producing strong winds. It looks like the strongest
winds have been delayed a bit, mainly late morning through late
afternoon. The strongest will be at/above 7500ft. We converted
the HIGH WIND WATCH to a HIGH WIND WARNING for the Snake Plain and
south central highlands through 7pm. We kept the WIND ADVISORY for
the Upper Snake Highlands in place, and added one for the
southeast highlands. This one will include the Cache Valley and
Bear Lake, although the strongest winds should be above 7000ft and
also for locations more adjacent to the Plain. Besides the usual
travel concerns for large and/or light load vehicles, where
topsoil is exposed and dried out, blowing dust is possible. Also,
where we manage to get light snow there is the potential for
blowing snow (perhaps minor drifting higher up). Obviously where
the warning (wind gusts near 60mph) is in place, impacts will be
higher. We wouldn't be surprised to see some minor wind damage or
power outages in those areas. By later this afternoon, winds will
begin to weaken pretty quickly. We will also a marked shift to
northwest winds across northern areas. A convergence band of
snow showers should develop and shift south across the Upper Snake
Plain and Highlands, mainly north and east of Idaho Falls toward
Rexburg, Island Park and the Teton Valley. A few
stragglers" could push toward Blackfoot and Craters of the Moon.
Winds will remain more westerly to the south and west. By tonight,
we quickly dry up and clear out. Where it does snow, totals should be
only an inch or two. Some higher ridges and peaks in the central
mountain and eastern highlands may see 2-4" before it ends.
Hopefully, everyone hasn't put away coats and such. It will be
cold again when you wake up tomorrow, low-mid 20s in the valleys
and single digits/teens in the high country.

This quick shot of cold air, is just that...quick. We should warm
up pretty nicely through midweek. We will be back to average/above
average temperatures by Wednesday. More showers are possible
Tuesday night and Wednesday. They will be light and more focused
in the mountains vs the Snake Plain.  Keyes

.LONG TERM...Wed night through Sun night. Upper level longwave
pattern shifts from a moderate amplitude ridge on the west coast to
the ridge de-amplifying some as it shift overhead of the Gem State,
by Sat night. This would leave us open for an atmospheric river
event, with abundant precipitation, at that point. Until then would
expect cool temperatures with the potential for light precipitation
Wed/Thu/Fri. The GFS want to bring in the warm air and large amounts
of precipitation starting Fri, while the ECMWF brings in the really
large amounts Fri night/Sat, and keeps moderate to heavy rain
through Sat night. Either way, it is a two day episode of heavy
rain with snow levels very high, as it was two weeks ago. Flooding
once again may be the main focus; much depends on how much snow
pack is left. Messick

&&

.AVIATION...The main factor this afternoon will be winds and LLWS,
with the clouds breaking out somewhat for the 5 airports just as the
wind increases. LLWS may especially be a problem at KSUN, aided by
the terrain that induces greater directional shear. This is all due
to a front crossing through today. The front will bring mainly rain
this morning, then dry out most places during the wind event. CIG
impacts appear to be limited to the Teton Basin and KDIJ. There
should be a return of cloud cover tonight, but little to no rain
after 03/00UTC, even for KDIJ. Messick

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 6 AM this morning to 7 PM MDT this
evening for IDZ017-020>022.

Wind Advisory from 6 AM this morning to 7 PM MDT this evening
for IDZ023>025.

Wind Advisory from 6 AM this morning to 3 PM MDT this afternoon
for IDZ019.

&&