Shelley, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

548
FXUS65 KPIH 311012
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
312 AM MST Tue Dec 31 2024

.SHORT TERM...Today and Wednesday.
Expect cooler temperatures today and tomorrow. Any precipitation
today and tomorrow should be snow for all locations. Today our
area is under weak high pressure with weak northwest flow aloft
with a very weak wave moving over the Montana Divide area. Very
light snow with very light accumulation is expected for our
Island Park/Montana Divide area this morning. Some patchy dense
fog this morning is possible across the area for our lower
elevations and valleys, mostly near water sources.

High pressure builds in from the west today into Wednesday
morning. Patchy to areas of fog are likely Wednesday morning
across our lower elevations/valleys. By mid to late morning
Wednesday moisture in northwest flow aloft moves into our area
bringing light to moderate snow across the area through Thursday
morning. Expect 2 to 5 inches of snow for the western Sawtooth
mountains with the rest of the Central mountains receiving 1 to 3
inches of snow. The Eastern Highlands will get more snow, with 2
to 9 inches of snow expected. The Big Hole mountains, Caribou
Range, and the Wasatch will get the higher amounts, 4 to 9 inches,
of snow late Wednesday morning into Thursday morning and will
likely need winter weather advisories. The rest of the
Southeastern and Eastern Highlands will see 1 to 5 inches of
snow. Valleys will get a trace to up to around 2 inches of snow,
with higher amounts along eastern benches and the Upper Snake
river plain. This system will favor areas that do well in west
northwest flow. The NBM model shows a 100 percent chance for
mountains along the Wyoming border, the Sawtooth mountains and the
Albion and Southern Hill mountains to receive 1 inch or more of
snow. The Snake Plain and the Eastern Magic valley, especially
eastern bench areas have a 40 to 60 percent chance to receive at
least 1 inch of snow. The Wasatch mountains, Caribou Range, and
Big Hole mountains have a 50 to 70 percent chance of receiving 4
inches of snow or more on Wednesday into Thursday morning. Expect
slight breezy winds with this system on Wednesday into Thursday
morning with wind gusts 15 to 25 mph with locally higher speeds.
TW

.LONG TERM...Thursday through next Monday.
By Thursday morning, snow from Wednesday`s system will be tapering
off with additional snow of about one to two inches in the Eastern
Highlands and Sawtooths. Precipitation begins to move back in on
Friday as a low moves into the Pacific Northwest, but most of the
moisture on Friday will be focused on the Central Mountains and
northern half of the Eastern Highlands. Most of this snow will be
fairly light and some snow WILL falls in the South Hills and
southeastern Highlands, but that light snow on Friday won`t start to
accumulate until that night. The passage of a cold front early
Saturday morning brings in a bit more organized push of moisture and
looks to bring some light snow to the valley floors as it arrives
early Saturday morning when temps will be in the mid to upper 20s in
the valleys. This isn`t a particularly strong cold front and will
only take our highs from low to mid 40s Friday to the upper 30s and
near 40 degrees for Saturday afternoon. Of note, QPF for this Friday
into Saturday system did drop a bit with the overnight forecast run,
so we will see if this back and forth trend continues and if we can
get things ironed out over the next few days. With the drop in QPF,
the NBM now only shows about a 20 to 30 percent chance of at least 6
inches of snow around Galena Pass, Emigration Pass, and Pine Creek
Pass from Friday evening to Saturday evening. In the mid elevations,
currently the NBM shows a general 1 to 4 inches of snow and up to an
inch of snow in the lower elevations.

A couple more weak shortwaves pass through the area on Sunday and
Monday and will bring us some more snow for the mountains and even a
little bit down in the valleys while cooling our highs into the low
and mid 30s for most. Overall, it remains a fairly active beginning
to 2025.
AMM

&&

.AVIATION...12Z Tuesday to 12Z Wednesday.
As mentioned in previous discussions, we`ve been watching for the
development of low stratus early this morning at our terminals.
There is plenty of it on satellite in eastern Idaho and we`re
already seeing some of it at IDA with back and forth VFR to MVFR
CIGs as we go from SCT011 to BKN011 and back. A similar scenario is
most likely to play out at PIH and potentially at BYI. The potential
for IFR CIGs is highest at IDA with the NBM showing a 25 to 35
percent chance through the morning hours and about a 10 to 20
percent chance at PIH, BYI, and DIJ. With some mid level clouds
around, some light seeder-feeder snow cannot be ruled out and some
of that light snow is even ongoing at DIJ. SUN is expected to remain
outside of all of this low CIG "fun" and remain VFR throughout
today.

Our next system will be arriving in eastern Idaho in the 12-18Z
timeframe on Wednesday which is just outside of the scope of this
TAF package for most sites, so expect a more impactful drop in
conditions with next TAF issuance for more of Wednesday morning.
AMM

&&

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

$$