Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 250012

Area Forecast Discussion
National Weather Service Pocatello ID
615 PM MDT Wed May 24 2017

.SHORT TERM...Tonight through Saturday. Warning level winds were
still being observed across the INL early this evening and warning
expiration time left me with a very short leash. Updated warning to
extend it through 9 PM MDT commensurate with Advisory that is
ongoing across the Lower Snake River Plain and to a much lesser
extent across the Eastern Magic Valley. The short term HRRR model is
showing the winds turning to the NW by around 8 PM and decoupling
rapidly so we may be able to expire the highlights by that time. See
the previous forecast discussion below. Huston

Strong winds in the Snake Plain will diminish this evening between 8
and 9 pm MDT with setting sun and decreasing surface pressure
gradient. Cold air and moisture moving south from British Columbia
will drop into Idaho tonight and Thursday to lower afternoon
temperatures about 7 to 10 degrees and bring some scattered showers
over the Central Mountains and Upper Snake Highlands. Snow levels
only dip to around 7800 feet elevation.
This trough remains over Southeastern Idaho on Friday before
finally moving off to the east Saturday. RS

.LONG TERM...Saturday night through Wednesday. GFS and ECMWF
ensembles give high confidence in established upper ridge in the
long-term period. The ridge axis should stay over WA/OR, leaving
Idaho in a broad northwesterly wind aloft. Dynamics for large-scale
ascent is lacking, but deterministic models persist in generating
showers and thunderstorms owing to diurnal heating and orographic
lift. Temperatures will edge upward through the period with highs
starting in the mid 70s across the Snake Plain on Sunday, to the mid
80s by Wednesday. Hinsberger

.AVIATION...Dry cold front moving through the area will keep wind
gusts around 35 to 45 kts across the Snake Plain this afternoon and
early evening. Given the dry nature of the front and the time of
year, areas of blowing dust may bring lowered visibility to KIDA and
KPIH. We have high confidence in the strong winds today, lower
confidence in the areal extent, intensity, and duration of the
blowing dust. Opted to put the MVFR visibilities in a TEMPO group
for this afternoon rather than predominant. Hinsberger

.HYDROLOGY...Temperatures will play a roll in snow melt and
runoff the next week or or more. Cooler temperatures Thursday and
Friday will help slow the melting, but by Saturday temperatures
begin a warming trend. A high pressure ridge expected to move
inland early next week will bring additional warming. Rain showers
over the mountains the next two days will add some new snow to
the upper peaks and rain on mid and lower slopes. RS

Wind Advisory until 9 PM MDT this evening for IDZ017-021.
High Wind Warning until 9 PM MDT this evening for IDZ020.

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