163
FXUS65 KPIH 250940
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
240 AM MST Mon Nov 25 2024

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...
A relative break between storm systems will hold on across southeast
Idaho today into this evening, before a fresh trough of low pressure
is forecast to bring rain and snow to the region from late tonight
through Wednesday morning. Mixing with rain is most likely from the
eastern Magic Valley and lower Snake Plain into our valleys across
the southern highlands, with otherwise mostly snow favored. The
Winter Storm Watch has been upgraded to a WINTER STORM WARNING for
the Bear River Range where 5-12 inches is expected (locally higher
amounts in the backcountry above pass level), and a WINTER WEATHER
ADVISORY has been issued for the Big Hole Mountains, Bear Lake
Valley, Blackfoot Mountains, and Caribou Range where 2-6 inches is
expected (locally higher amounts in the backcountry). This
represents a very slight increase in forecast snow totals compared
to our previous forecast, still leaning mostly on WPC guidance.
Elsewhere, totals will range from a light coating to 3-4 inches in
other mountain ranges...a bit modest for advisories but carrying
some potential for slick spots on the roads as well. Overall winds
look modest with this system, so impacts will be very tied to
falling snow producing slick roads and reduced visibility. High-res
models do exhibit some disagreements in some of the timing/placement
details on snowfall, with the HRRR and NAMNest more aggressive in
lifting an organized region of snowfall across much of the central
and southern CWA including the Raft River region and Snake Plain
from late overnight tonight into Tuesday morning. We broadbrushed
higher PoPs northward more quickly in the forecast tonight
coincident with this signal, but otherwise have held close to NBM
guidance (with WPC calibrated QPF) with few edits as we monitor
trends in the data and CAMs (and the QPF forecast does already
reasonably light up most of this corridor Tuesday morning). This
system will culminate in an organized cold front crossing the CWA
from NW to SE Tuesday afternoon or evening...it`s not yet clear
whether or not this will support a final push of convergence-
enhanced snowfall as the sfc wind forecast is a bit weak/messy, and
simulated reflectivity on the CAMs is just starting to cover this
period. Expect a cooling trend in temps over the next 3 days. 01

.LONG TERM...WEDNESDAY THROUGH NEXT MONDAY...
The storm in the short term will be winding down on Wednesday.
Colder air will be pouring into the region post-cold-front. Highs
in the extended will generally be in the lower to mid 30s in the
Snake Plain and Magic Valley. Single digit lows in the Snake Plain
and Magic Valley are certainly possible as well. Most of the long
term looks dry as well. For the remainder of this week, there`s
an outside chance of light snow in the Island Park region. This is
likely the model picking up on low stratus with flurries falling
out of it, maybe some seeder feeder action occurring. In either
case, this would amount to little to no accumulations. Early next
week, some model solutions are bringing a weak shortwave through
the region. This would potentially result in some light
accumulations across central and east Idaho, but low confidence at
this point of that occurring. 13

&&

.AVIATION...
Quiet, VFR conditions are forecast to continue today, with clouds
gradually thickening and lowering this afternoon and evening ahead
of our next approaching storm system. Precipitation will arrive from
south to north overnight tonight into Tuesday morning at the TAF
terminals...will be timing this out in the forthcoming 12z TAF
package. The greatest impacts will likely initiate near or just
beyond the end of the current forecast period Tuesday morning with
MVFR cigs/vsbys looking likely at KBYI, KPIH, KIDA, and KDIJ. 01

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from 11 PM this evening to 10 AM MST
Wednesday for IDZ060.

Winter Weather Advisory from 11 PM this evening to 10 AM MST
Wednesday for IDZ061>064.

&&

$$