349
FXUS65 KPIH 221138
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
438 AM MST Fri Nov 22 2024

.UPDATE...To reflect expiration of some warnings at 0500 MST, and
the upgrade of the watch to a warning for tonight, plus the
addition of two zones reaching Winter Weather Advisory Level

&&

.PREV DISCUSSION... /issued 224 AM MST Fri Nov 22 2024/

SHORT TERM...Today through Sun night. The current Winter Storm
Warning in effect until this morning will be allowed to expire at
0500 MST. At that time, will likely promote the Winter Storm Watch
to a Warning and add a Winter Weather Advisory for the upper Snake
River Highlands, as snow accumulations spike upwards again
starting late this evening and lasting through much of Sun night.

Not to say that central and eastern Idaho will not receive snow
today; it is staying above 7000ft, only in the central Idaho
mountains, and staying mostly below the 6 inch accumulation
threshold for today and this evening. The next embedded trough
moves through the mean southwesterly upper level flow and yet
another atmospheric river event occurs. This one brings a fairly
high snow level with the warmest temperatures seen since 11
November. But where snow falls in the central Idaho mountains, it
is fairly heavy for the 24 hour period. The snow will continue in
the eastern highlands until Sun afternoon, so the Winter Weather
Advisory will for this area will last longer than the Winter Storm
Warning does for the central Idaho mountains--it should be
clearing out there during the very late night hours on Sat night.

At the lower elevations, rainfall will be light to moderate
starting tonight, so nothing like California with any kind of
flooding. Zero snowfall, save for the high ground around Craters
of the Moon and north of St Anthony.

The mild air will allow those warm temperatures today, with middle
50s from the Pocatello area south and west at low elevations. Even
Stanley warming into the middle 40s, Challis to the lower 50s. The
cloud cover returns to keep overnight lows somewhat mild. The next
storm has even more cloud cover for Sat night than Fri night and
temeperatures are still mild, even though Sat afternoon highs are
not as warm as today`s. The cold air moves in on Sun and afternoon
highs continue the downward trend. Coldest night of the week
occurs Sun night as skies partially clear and precipitation ends
late.

Wind is light to breezy today and tonight, but on Sat afternoon
some windy conditions develop over the Arco Desert from Craters of
the Moon to Mud Lake, extending to just west of Idaho Falls. Wind
is light again for Sun/Sun night.
Messick

LONG TERM...Mon through Thanksgiving night. A positive-tilt
trough moving through a more westerly flow will again bring rain
and snow, with snow over more areas and without the subtropical
connections. Snow will thus be at lower elevations, including the
floor of the Snake River plain, on the heavy travel day Wed. Tue
won`t be much better, and is more likely to have the lion`s share
of the precipitation. the holiday will be cold with lows
Thanksgiving morning hovering at 15-20 deg F for the heavily
populated areas, single digits for the basins of central Idaho.
Highs will only manage to get into the lower or middle 30s for
those same elevations, middle to upper 20s for highland locations
in the northeast. Cluster forecasts were not available for
Thanksgiving Day, and it should be noted there is a 35 percent
chance of precipitation, but it is heavily influenced by climatic
averages for the time of year.
Messick

AVIATION...
VFR conditions will reign today and tonight as southeast Idaho
experiences a break in local impacts from the ongoing atmospheric
river event. Mid-level cigs will rise and trend BKN, perhaps even
SCT at times as sfc winds stay light at less than 10kts. Clouds
will thicken and start to trend modestly lower again Saturday
morning as rain and snow returns to KSUN likely prior to sunrise.
While KSUN will yet again see the greatest initial impacts, we do
expect at least some organized rain/snow showers will eventually
cross all terminals during the day on Saturday with MVFR cigs and
brief hits to vsbys (tied to snow showers) possible. 01

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 AM Saturday to 5 PM MST Sunday
for IDZ066.

Winter Weather Advisory from 11 PM this evening to 11 PM MST
Saturday for IDZ069-071.

Winter Storm Warning from 11 PM this evening to 11 PM MST
Saturday for IDZ072>074.

&&

$$