841
FXUS65 KPIH 232107
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
207 PM MST Mon Dec 23 2024

.SHORT TERM...Tonight through Tuesday night.
Will have lingering very light snow in the eastern mountains
tonight but expecting less than a half inch additional
accumulation. Late tonight through tomorrow morning will be dry as
upper ridging slides through Idaho ahead of the next system. Snow
will move into the central mountains Tuesday afternoon and
overspread the remainder of the state Tuesday night. Expect
widespread but light snow with rain in low elevations possible.
Snow levels start out 6 thousand to 6500 feet Tuesday afternoon
but drop to between 4500 and 5 thousand feet later Tuesday night.
General amounts expected are 1 to 3 inches through Wednesday in
the mountains and under an inch in the Snake River Plain and low
elevation valleys. Lows tonight in the 20s and 30s with highs
Tuesday in the 30s mountains and 40s lower elevations with lows
Tuesday night in the 20s and 30s once again. Overall very mild
with mainly light winds.
GK

.LONG TERM...Christmas Day through next Mon evening. No clusters
analysis was available except for Sun and Mon. Flatter upper level
flow means a faster progression of storms and lower confidence in
timing. However, it can be said that precipitation will continue
into Christmas morning at a minimum from the storm at the end of the
near term forecast. For eastern portions of the forecast area, it
may continue through the afternoon, especially in the northeast
corner of the forecast area. Nearly everywhere will experience a
break on Christmas night, but on Thu morning, moisture will spread
eastward and bring light to moderate rain and snow to all of eastern
Idaho. Heavier amounts should be in the northern half, and at higher
elevations. Snake River plain amounts on Thu should be 0.10 to 0.20,
0.20 to 0.40 in the mountains. This would convert to snow that could
reach Winter Weather Advisory levels for Thu, especially adding in
Thu night and Fri. It does lighten Thu night, and continues through
Fri. Fri night and Sat also have chances of light precipitation,
with snow levels rising in the mild air of the atmospheric river.
There is no significant letup after Christmas Night until perhaps
Mon.

Below 6200ft elevation, temperatures will be rising each afternoon
above freezing, making for a sloppy mess at the lower elevations.
Timing is critical as to whether there will be actual snow
accumulation; the better accumulations in the afternoon may mean
more snow. So take snowfall amounts with a grain of salt after Thu
afternoon, at least for now. Temperatures should warm, albeit
slightly, for the Sat-Sun period, then cold air finally returns Mon
afternoon, possibly. Again, it is a low confidence forecast for the
weekend period at this time. A 500ft change in snow level could mean
more snow at lower elevations and a harder travel period.

Except for the Boxing Day (Thu) storm, wind should be light, and
even for that storm, would only expect brisk/breezy conditions in
the post-frontal passage time frame on Fri morning.

Messick

$$

.AVIATION...23/18Z through 24/18Z. CIG and VSBY conditions should be
stabilizing and precipitation should end by this evening, with KDIJ
the last at 24/01Z. Most other airdromes will see precipitation end
during the early afternoon. Only KSUN and KDIJ are flirting with
airport closure this afternoon. The main issue tonight will be
fog and stratus making conditions difficult, especially in the two
northern airports of KIDA and KDIJ. Outside of those two
terminals, the rest should be dealing with marginal VFR conditions
at worst for tonight and Tue morning.

Messick

&&

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

$$