Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 040858
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
158 AM MST Sun Dec 4 2016

.SHORT TERM...Today through Tuesday night. Upper disturbance and
its associated cold front continue to track southeastward from
Vancouver Island. Initial impacts will be over the Central
Mountains where the onset of the moderate to heavy snowfall will
begin between 6am and 9am. Snow intensity and wind speeds will
pick up over the Eastern Highlands later this morning and into the
afternoon as the surface front approaches. The front should
finally pass through the Snake Plain tonight as windspeeds peak
around that time. This will present the possibility of blowing
snow. Winds will remain strong through early Monday morning, then
slowly diminish as the gradient loosens. Models bring cold
temperatures after the system finally passes on Monday, but
NAM/GFS differences appear Monday evening and Tuesday as the NAM
appears the drier solution for the forecast area, or at least
offering later timing of the next upstream system. Hinsberger

.LONG TERM...Wednesday through next Sunday. The GFS and ECMWF are in
good agreement this morning at least with regards to the development
of Pacific storm systems. However, they may differ by as much as
12hrs on the timing of the passing systems. Generally speaking, it
looks as if the next Pacific storm system will begin impacting the
region as early as Thursday night and continue through Saturday
morning before we begin to see some improvement through the day. The
GFS drives a second storm system through SRN Idaho Sunday while the
ECMWF has similar timing but is significantly weaker and less
organized with its system. Statistical guidance shows a gradual
warming trend through Friday as the next storm system approaches
with daytime highs remaining cold enough to support snow throughout
the forecast period. Huston
&&

.AVIATION...Early morning satellite imagery was showing the next
Pacific storm system digging into the NW Canadian coast with a
stream of moisture directed at Idaho. Numerical models show the
moisture pushing across SE Idaho today with enhanced precipitation
potential along the NW facing slopes of the CNTRL and ERN mountains.
The valley terminal sites get involved as the frontal boundary
sweeps through the area sometime late this afternoon and evening. At
a minimum I would anticipate at least MVFR CIGS with periods of IFR
or LIFR CIGS/VSBY in SN at KBYI, KPIH and KIDA this afternoon/eve.
KSUN may actually fair well in downslope flow through about 18Z
before taking a digger as the frontal boundary rolls through the
region. KDIJ will likely descend from MVFR CIGS early this morning
to IFR and LIFR conditions by at least the 12Z forecast issuance and
remain their throughout the duration of the forecast. Cross sections
show improving conditions at all remaining terminals after 06z
tonight in the wake of the frontal passage. Strong SW to NW winds
will contribute to LLWS and turbulence. Huston

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 8 AM this morning to 6 AM MST Monday
for IDZ032.

Winter Storm Warning from 8 AM this morning to 5 PM MST Monday
for IDZ019-023.

Winter Storm Warning from 6 AM this morning to midnight MST
tonight for IDZ018-031.

Winter Storm Warning from 2 PM this afternoon to 5 PM MST Monday
for IDZ025.

&&

$$



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