533
FXUS65 KPIH 181917
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
117 PM MDT Sat Oct 18 2025

.KEY MESSAGES...

- Our next fast-moving, generally low-impact storm system is
  expected to bring rain and snow showers, along with breezy
  conditions, Sunday afternoon through Monday morning.

- Dry conditions are forecast for much of the week.

- Next precipitation maker arrives next weekend.

&&

.SHORT TERM /THROUGH SUNDAY NIGHT/...
Issued at 117 PM MDT Sat Oct 18 2025

Dry conditions continue tonight as East Idaho remains under
influence of dry northwest flow. Precipitation overspreads East
Idaho Sunday, starting across the Frank Church as a mix of
valley rain and mountain rain/snow around mid-morning. Front
progresses through the region late Sunday into Sunday night.
Ahead of the front, enough instability is present for isolated
thunderstorm development across the eastern highlands. Snow
levels begin falling behind the front late Sunday, progressing
west to east, bringing snow down to around 5000 ft across the
central mountains and Snake Plain, slightly higher across the
southeast by late Sunday night. Did lower forecast Snow Levels
slightly based on surface temperature progression through the
night. Model QPF estimates rose slightly again with latest runs,
resulting in higher snowfall amounts above 6500 ft. In general,
however, accumulations remain light. The chances of seeing more
than 4" of accumulation are highest along the spine of the
Sawtooths and the higher elevations of the Frank Church and the
Pahsimeroi range. Winds remain the only other concern as the
shortwave pushes through Sunday. Sustained speeds across the
Snake Plain look to range 25 to 30 mph with gusts 35 to 40,
highest across the Arco Desert, where there is about a 25% for
gusts to approach 50 mph. At this time will hold off on a Wind
Advisory, but winds are expected to bump against the lower
thresholds for a few hours in the afternoon across the northern
portions of the Snake Plain.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Issued at 117 PM MDT Sat Oct 18 2025

Showers, including light snow at high elevations, should wrap
up prior to noon on Mon except near the ID-WY border where it
will linger into the afternoon. Skies will clear with upper
level ridging continuing through at least Thu afternoon. At that
time, an upper level trough will be moving through the eastern
Pacific, trying to move onshore. It will take until Saturday for
this low to set up on the coast and start ejecting short wave
lows through the Pacific northwest and into the Gem State.

Overnight lows will drop below freezing for all locations on
Mon night. Lows bottom out on Tue night, then start to warm
thanks to afternoon highs once again warming to above normal by
Tue afternoon. Temperatures will even reach the 60s at low
elevation in the Snake River plain and southern hills.

Wind on Mon will be strong, possibly at Wind Advisory levels
for the Snake River plain, maybe the eastern Magic Valley.
However, wind will be over by Tue morning with light wind until
Thu as the new low approaches.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1048 AM MDT Sat Oct 18 2025

A few cumulus this afternoon at KPIH and KSUN, otherwise it
starts with high cloudiness in the early evening, then mid-level
cloudiness developing over the late night hours. However, no
CIGs are expected until after 19/18Z, so only KSUN has CIGs and
VCSH in the TAF at this time. The more important forecast
element is the wind. Light and variable conditions should start
turning to the south and southwest, with wind increasing. Wind
gusts of 25KT should develop around 19/17Z or around that time.
KPIH with downslope wind may gust earlier. The same could be
true for KBYI.

&&

.FIRE WEATHER...
Issued at 405 AM MDT Sat Oct 18 2025

After dry and mostly clear/sunny conditions today with drier
afternoon humidity values, our next fast-moving storm system
will bring rain and snow showers across the region from Sunday
morning through Monday morning. Winds with this system continue
to trend slightly stronger for Sunday afternoon and Sunday
night, with many areas seeing gusts of 25 to 35 MPH (40 MPH over
the Arco Desert region). Meanwhile, precipitation amounts
instead of continuing to trend drier have increased just a bit,
with wetting rain/snow looking especially likely across Zone
475, northern Zone 422, and along the immediate WY border
corridor from Caribou County north into the Island Park region.
Dry weather returns from Monday afternoon through much of the
rest of the coming week behind this system.

&&

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

&&

$$

SHORT TERM...DMH
LONG TERM...Messick
AVIATION...Messick
FIRE WEATHER...01