Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 170849

Area Forecast Discussion
National Weather Service Pocatello ID
249 AM MDT Fri Mar 17 2017

.SHORT TERM...Today through Sun night. High pressure will continue
to dominate today and this evening, but a shortwave to the west
will, very slowly, break this ridge down. It will start in the
extreme western zones in the central Idaho mountains late tonight,
and take all day Sat and into Sat evening before the clouds and
potential precipitation reach the ID-WY border. The precipitation
will continue Sun, and partially clear from northwest to
southeast across eastern Idaho Sun night. So expect, with the
fewest clouds Today and Sat, that temperatures will peak in the
west Today and for the eastern locations on Sat. The snow level
is staying very high, although the locations where it will be
lowest are some of our higher elevations, mainly in Custer and
Blain Counties. Snow level could drop as low as 7000 ft, so it
will be of limited areal coverage if there is snow. It should also
be allowed to melt quickly, as the snow level recovers after the
trough passes. Breezy to windy conditions possible on Sun after
the frontal passage. Messick

.LONG TERM....Monday through Friday. A flat ridge struggles to build
across the region Monday as the next PAC storm system advances
toward the coast. Enough moisture sneaking over the ridge at this
point to support a chance/slight chance mention of precipitation. By
Tuesday afternoon, the disturbance lifts NE into the coastal waters
with both the GFS and ECMWF placing the bulk of attending
precipitation over Washington, Oregon and WRN Idaho. The CNTRL Idaho
mountains may stand a chance of seeing some fairly decent rainfall
with snow levels rising above 8000 MSL. The remainder of SE Idaho
will likely see a weak chance of precipitation through Thursday as
trailing energy passes through the region. The third in the series
of PAC storm systems approaches the NW coast Thursday afternoon.
Here the models differ greatly in the placement and track of the low
Thursday night and Friday with the GFS taking a more northerly track
into WRN Canada whereas the ECMWF is much slower and further south.
Plan at this point is to maintain some mention of precipitation
across the region until the models show greater consistency.
Statistical models still running well above normal on daytime temps
throughout the period. Huston

.AVIATION...Early morning satellite imagery was showing SCT high
clouds passing overhead as the next PAC disturbance advanced slowly
toward the NW coast. Numerical models suggest variable mid- and
upper CIGS as we await the arrival of the aforementioned storm
system which is set to move onshore late Saturday into Sunday.

.HYDROLOGY...Have kept all things the same, since updates are
necessary in coordination with County emergency management. There
are 5 Flood Advisories: lower Blaine County, western Bingham
County, central Minidoka County, northeast Caribou County, and
southeast Bear Lake County. It sounds as though the Bear Lake
County Flood Advisory may need to extend through all of southern
Bear Lake, but it will require coordination not available
overnight. There is also a mainstem River Flood Warning for the
Portneuf near Pocatello; the river stage should cross into minor
flood stage very late Sat night/very early Sun morning. The Flood
Watch continues for a number of Counties, most notably not
including Custer, Cassia, Jefferson, and Madison Counties, but
portions of the other counties continue under threat. Messick


Flood Watch through this afternoon for IDZ017-019-021>025-031.


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