Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 030858

Area Forecast Discussion
National Weather Service Pocatello ID
158 AM MST Sat Dec 3 2016

.SHORT TERM...Today through Monday night. Weak forcing aloft is
resulting in light returns on the radar this morning, particularly
along Interstate 15. A weak anticyclonic flow will slowly
deteriorate throughout the day today as a cold front drops in from
the Alaskan panhandle. Models are keeping things fairly dry today
except for some light upslope showers over the Eastern Highlands.
As the cold front advances, we will start to see an increase in
snowfall late Sunday morning starting in the Central Mountains,
then spreading to the rest of the forecast area Sunday night.
Gradient winds sharply increase Sunday night into Monday,
resulting in strong winds and an increased potential for blowing
snow. Heaviest snow accumulation will be along the front with
total accumulations of 5 to 8 inches in the Central Mountains and
the Island Park/Driggs area, and about 1 to 3 inches in the
valleys including the Snake Plain. Blowing snow will also impact
the area with visibility possibly being reduced to a quarter mile
or less in some areas. Conditions should improve as the 500mb
trough passes Monday afternoon. Hinsberger

.LONG TERM...Tuesday through next Saturday. The GFS and ECMWF
appear to be coming into better alignment on the track and timing of
incoming systems through the period and thus have generally nudged
the forecast in the direction of the current progs. A secondary PAC
disturbance trails across the region Tuesday supporting scattered
snow showers across the region. This wave exits east of the region
Tuesday night with drier conditions anticipated Wednesday and
Wednesday night. The GFS is still indicating a fairly flat ridge
over the region Thursday which allows PAC moisture from the next
approaching storm system to spill over the ridge into at least the
CNTRL mountains by Thursday afternoon and spreading into most of the
remainder of SE Idaho by Friday morning. The ECMWF has made a move
toward the GFS solution and away from its previously strongly
amplified ridge and dry solution. Main onslaught of moisture from
this system appears to move onshore Friday with lingering snowfall
into Saturday as a modest ridge struggles to redevelop along the NW
coast. Statistical guidance continues to show Tuesday and Wednesday
being unseasonably cold with a slow warm up into more seasonable
temperatures toward the end of the week. Huston

.AVIATION...A Pacific short-wave was noted shearing SE into the NRN
Rockies early this morning with attending moisture spilling into the
region. Numerical models suggest that most of the snowfall will be
confined to the Montana/Wyoming divide regions with possible CIG and
VSBY impacts at KDIJ and KIDA through the day. The infusion of
moisture into the boundary layer will promote IFR stratus
development at KPIH, KIDA and KDIJ through the overnight hours with
KBYI and KSUN being largely spared. Huston


Winter Storm Watch from Sunday morning through late Sunday night
for IDZ018-031-032.

Winter Storm Watch from Sunday morning through Monday afternoon
for IDZ019-023.

Winter Storm Watch from Sunday morning through Monday afternoon
for IDZ025.


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