Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 201039

Area Forecast Discussion
National Weather Service Pocatello ID
339 AM MST Fri Jan 20 2017

.SHORT TERM...Today through Sunday night. Expect lingering light
snow showers today. A weak trough moves across our area tonight
into Saturday. Models continue to show about 1 to 2 inches of
valley snow and 2 to 4 inches of mountain snow. The Wasatch
mountains may see slightly higher snow amounts.

A cold front moves through the area Sunday into Monday. Currently
models are showing 3 to 6 inches of valley snow and 6 to 12
inches of mountain snow particularly across our Southeast areas to
include the Southeast Upper Snake Highlands, the Caribou
Highlands, the Wasatch mountains, and the Eastern Southern
Highlands. There is a potential that the Snake River Plain
particularly the Eastern benches could see significantly more than
3 to 6 inches of snow depending on system intensity, track, and
snow levels. TW

.LONG TERM...Monday through Friday. Models remain consistent with
each other and the general pattern but again struggle with details
tonight. Pacific trough slides across intermountain west Monday,
closing off somewhere in the lee of the Rockies. Monday should
remain wet and unsettled, continuation of Sunday storm. As upper low
and trough axis shift east of the region Monday night, expect wrap
around precipitation to affect mainly eastern portions of the
forecast area. Placement of the upper low and extent of deformation
zone wrapped around north of the low could focus precipitation into
the southeast corner, which could be indicative of heavier snowfall
during that time period, similar to a convergence event for the
Snake Plain. Upper low shifts far enough east Tuesday, with
northerly flow in place. Both GFS and ECMWF now agree on secondary
shortwave wrapping around the low and clipping Idaho for threat of
light snow continuing mainly higher elevations Tuesday and
Wednesday. Solutions continue to portray ridge through coastal
states late Wednesday into Thursday. Quite a bit of ensemble and
model disagreement on the amplification of the ridge, but overall
should be drier all areas and continued cold. DMH


.AVIATION...Initial shortwave activity keeping pockets of light snow
tonight under stratus deck. Conditions over E ID vary from VFR to
IFR, and should expect this trend to continue early into the
daytime. Improvement to VFR expected most areas. Exception will be
KSUN where southerly flow up valley will enhance stratus potential
and keep ceilings close to minimums. Next feature pushes into region
by late afternoon. KSUN and KBYI first to see snow, sometime around
00Z, then spreading to KIDA/KPIH by/around 06Z. KDIJ will be the
last to see snow, and some indication that it might not materialize
there at all. Expect ceilings to drop to IFR most areas, with
exception of KDIJ which may remain VFR through tonight. DMH



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