Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 132057
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
157 PM MST Tue Feb 13 2018

.SHORT TERM...Tonight through Thursday night.

Many areas across east Idaho have been dealing with pesky low level
stratus today. These clouds have lifted in many areas but may
redevelop again tonight. Favored areas include the upper Snake Plain
down to Pocatello and valleys along and east of I 15. Meanwhile, we
await the next storm system which will arrive from the northwest
Wednesday afternoon. Precipitation will be mainly confined to the
high country as we are expecting gusty winds to develop across the
Snake Plain and Magic Valley which will produce downslope effects.
Assuming precipitation makes it to the surface could see a rain snow
mix in the lower elevations. Cold front will move through the region
during the evening which should bring snow levels completely down to
valley floors. Still, moisture with this system is not overly
impressive with snowfall potential likely to be less than an inch
for most of the valleys including the Snake Plain and Magic Valley,
with a couple of inches possible closer to pass level and around the
Island Park, Stanley areas. We may a few residual snow showers still
around on Thursday as a moist northwest flow continues across the
region, however additional snow amounts look very light.

Valle

.LONG TERM...Friday through next Tuesday. A weekend cold front
remains in store with its passage now forecast for Sunday evening.
Friday into Saturday there is still some noticeable differences
between the two main global models. An unstable weather pattern
emerges Friday; leading to some mountains snow showers becoming
likely during the afternoon/evening hours Friday. These showers are
expected to continue into Saturday morning. Variances in the
progression of several shortwave troughs during the day Saturday
then lead to the differences in the forecast, which continue through
Sunday. At this juncture, the GFS model is emphasizing more snow on
Saturday and again Monday, which the ECMWF is favoring snow Sunday
(and maybe some on Monday). This will make our forecast in timing
and snow amounts less confident over the weekend as a result. What
does seem certain though, is that it is expected to snow in the
mountains with some snow probable in the valleys as well.
Temperatures Sunday through Tuesday are either near or below normal
for highs, which are in the 30s or 40s across the Snake River Plain
and 20s or cooler in the mountains. At the moment, Tuesday morning
is looking to be the coldest morning in the forecast period.
NP/Valle

&&

.AVIATION...Decreasing area of stratus still noted on satellite
imagery this afternoon across the Snake River Plain, and only
affecting IDA. The forecast for IDA does improve the ceiling a bit
but does not take the stratus out of the site completely. Going into
the late evening/overnight hours, expect the low stratus to
redevelop at PIH and possibly near SUN. Otherwise, ceilings are VFR.
Ceilings and visibility are VFR at DIJ with no wind concerns as
well.

Confidence in the forecast at BYI is quite low regarding the IFR
ceilings, and if the visibility will drop or not. There is no model
consistency between the short term solutions and it is therefore
making the forecast very tough. One solution does lower visibilities
between 2 sm an 1/4 sm...just north of Burley. Other models have BYI
too windy.
NP/Valle

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$



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