Area Forecast Discussion
Issued by NWS Pocatello, ID

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364
FXUS65 KPIH 022042
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
142 PM MST Fri Dec 2 2016

.SHORT TERM...Today through Monday...Upper ridge continues to
drop over East Idaho tonight. Surface inversions remain in place
with low stratus and potential redevelopment of patchy freezing
fog across lower elevations. Caveat is shortwave moving quickly
through BC Canada Thai afternoon. Energy could be enough
overnight to keep a slightly mixed profile to prevent fog from
forming. Better chances are though for mid level cloud to combine
with some upper level energy to produce seeder/feeder snows in
existing stratus layer. Have kept precip probs low except over
northern zones with gradually increasing chances overnight.
Northwest flow through the day Sunday and into Sunday night ahead
of next system will keep upslope chances for snow mainly across
higher elevations east of I-15.

A significant winter weather system will pass through Idaho Sunday
and Monday. A strong cold front will sweep through on Monday.
Conditions will quickly deteriorate under Heavy Snow Sunday in
the Central Mountains early Sunday. Blowing snow will be a
significant factor in this winter storm as well. Winds are
expected to gust in excess of 40 mph at times Sunday afternoon and
evening, particularly at higher elevations. These conditions will
persist through the evening in this region while progressing
southeastward with the front. Heavy Snow to start in the east late
Sunday morning. A Winter Storm Watch is in effect for these
conditions. Snake Plain regions should expect light snowfall,
under 3 inches total with averages of 1 to 2 inches on Sunday and
Monday. Make your family communication plan for Sunday and Monday
for this event. Know where your loved ones are in case of an
emergency. NP/DMH

.LONG TERM...Tue through next Fri night. The GFS and ECMWF have
come closer in agreement today compared to the previous two days.
In this game of meteorological "Chicken" the ECMWF has lost; it
has come around closer to the GFS solution, although both have
changed somewhat. The ECMWF now has more precipitation, although
with the first storm the ECMWF is slower to forecast its arrival
(Thu night instead of the GFS Thu arrival). Both are similar in
the magnitude of the event. This storm will likely come with some
windy to very windy conditions, besides moderate to heavy
snowfall. Temperature- wise, while there is no longer any below-
zero temperatures for the Snake River plain, there is single
digits in the arctic pool of air left behind by the Mon/Mon night
storm. Messick

&&

.AVIATION...Stratus has stayed in in some locations, mainly in the
Snake River plain. Moisture-rich boundary layer will bring back
stratus and possibly fog everywhere except KSUN. However, some areas
will develop some dry advection and will clear before sunrise. KIDA
will likely be the problem child with near/below field minimums
likely again. The most difficult forecast is for KDIJ, where the
guidance is limited to GFS; its performance has been underwhelming
for this event. KPIH and KBYI are the locations that should begin
clearing during the early morning hours on Sat. Light wind expected.
Messick


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
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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