High Wind in Idaho, November 1 to 2, 2022

Area Forecast Discussion
National Weather Service Pocatello ID
203 PM MDT Tue Nov 1 2022

.SHORT TERM...Tonight through Thu night. A pattern change started
this morning as an approaching low boosted the wind above Wind
Advisory thresholds in the Pocatello area, with breezy to windy
conditions elsewhere. This low will bring light accumulations of
mountain snow, light rain to the valley floors (under 0.10 of an
inch for most). The cold air mass behind the associated front will
drop temperatures 15 to 25 deg F behind the front for the
afternoon highs from this afternoon to Wed afternoon. The
precipitation continues after a late start tonight, starting first
in the central Idaho mountains and spreading eastward before 0600
MDT Wed morning.

The main forecast problem is the strength of the wind expected.
Yesterday it was a very confident High Wind Warning for the valley
zones (except for the Shoshone area) and eastern and southern
highlands. Confidence for Warning level is down, as the NAM has
backed off and the NBM has decreased expected wind as a result.
However the operational GFS has continued bullish on the wind and
other ensembles continue to support, for some locations, High
Wind. The 500mb wind peaks 02/12Z on all guidance products, and
the surface low gets organized and develops a strong gradient
across southern Idaho at the same time. The main difference
between the GFS and the NAM is the 700mb wind, where the GFS has
40KT to 45KT compared to 30KT to 35KT on the NAM. The one sure
thing from this event will be blowing dust, and it would not be
out of the realm of possibility that a short-fuse Dust Storm
Warning be issued during the overnight and early morning hours.

The wind will subside on Wed night, but precipitation continues.
The upper level trough sweeps through during the day Thu. The
amounts should be limited to highlands and mountains, except
perhaps the eastern Magic Valley close to the Albion zone.
Temperatures continue cold with freeze-thaw conditions at
Snake River plain elevations. Thu night features a break in the
weather, but the weather pattern keeps the storm track over the
Gem State.

.LONG TERM...Friday through next Tuesday.
Weak high pressure will briefly build back in through early Friday
and therefore we may see partial clearing of skies for a very brief
period.  High temperatures Friday will run within a few degrees of
Thursday's highs, with mid-30s to low 40s across the Snake River
Plain and eastern Magic Valley and 20s to low 30s in the higher
terrain.  Temperatures will warm by 5 to 10 degrees Saturday before
the ridge flattens due to the influence of a Canadian low.  Winds
will begin to increase Friday ahead of the system, with winds
gusting to around 35 mph across the Snake Plain and Magic Valley on
Saturday as the cold front passes. The ECMWF Extreme Forecast Index
(EFI) is highlighting the central mountains and Snake River Plain
for enhanced winds on Saturday.  Models have come into better
alignment regarding the timing and depth of the upper trough.  At
this time, precipitation looks to be impressive with this event and
models increasingly show favorable Integrated Water Vapor Transport
(IVT) into the area.  The National Blend is introducing
approximately 50-90% PoPs across the region again Saturday through
Sunday, with the greatest accumulations expected across the
Sawtooths and eastern and southeast highlands. Cropp

&&

.AVIATION...A cold front will pass tonight into tomorrow
morning, bringing up to 50 mph gusts to all terminals, with the
exception of KSUN, which is expected to see gusts in the 20 kt
range.  Windy conditions will persist through tomorrow morning and
precipitation will reach KSUN first this afternoon and spread
eastward to the other terminals during early morning tomorrow.  VIS
impacts are expected due to blowing dust and snow, with periods of
MVFR and IFR anticipated.  All precipitation should exit the region
to the east during the afternoon Thursday. Cropp

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
High Wind Warning from 6 PM this evening to noon MDT Wednesday
for IDZ052>066.

&&