Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 061056

Area Forecast Discussion
National Weather Service Pocatello ID
356 AM MST Tue Dec 6 2016

.SHORT TERM...Today through Thursday. Upper low over coastal
Washington will swing east/southeastward today. Radar and surface
observations indicate snow over the Columbia River Basin and
should be in the Central Mountains this morning and expand into
the rest of southeast Idaho this afternoon/evening. Overnight lows
will be frigid tonight and tomorrow night. Pacific moisture is
set to stream into Idaho on Thursday with some minor timing
differences between models. Forecast soundings indicate precip
will begin as snow. We are not expecting freezing rain during the
short-term period at this time, but warm air advection will be
ongoing heading into Thursday afternoon. If timing of the onset of
precipitation gets bumped up, snow may change over to freezing
rain, but low confidence in that this far in advance. Hinsberger

.LONG TERM...Thursday night through next Tuesday.  The GFS and ECMWF
models continue to show a significant winter storm system impacting
the area Thursday afternoon through Saturday. The models have come
more in line with each other, though the GFS model continues to be
slightly faster on Thursday in bringing this system in. Models
continue to bring warmer temperatures on Friday as well as backing
off on some of the precipitation on Friday. As the upper levels warm
up, there is a potential for freezing rain particularly in localized
valleys on Friday. The models continue to show another big surge of
moisture Friday night into Saturday. Models show the Western Central
mountains and the Eastern highlands getting 8 to 12 inches with
locally higher amounts. Models continue to back off on valley snow
particularly along the I-84/I-86 corridor because of strong,
downslope winds. Currently, 2 to 4 inches of valley snow is
expected. However, if models continue bring in warmer air, these
valley snow amounts will drop.

Models show two more surges of moisture through the end of the
period, though their timing and intensity vary.  Both models show a
light to moderate surge of moisture on Monday. Models show cooler
temperatures bringing light to moderate snow across the area. For
Tuesday, the GFS model shows a strong surge of moisture while the
ECMWF model shows a weak to moderate surge of moisture. Expect
warmer temperatures on Tuesday bringing back the possibility of
valley rain and/or a valley rain/snow mix. Wyatt


.AVIATION...Expect VFR conditions this morning for all TAF sites.
There is a slight chance of fog early this morning particularly for
KIDA. There is a weak upper level disturbance that will bring MVFR
CIGS/VIS to the TAF sites starting early this morning for KSUN and
slowly progressing Eastward through the afternoon into the evening.
Models are showing the Cigs to start to lift by early to mid
tomorrow morning. Wyatt



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