High Wind in Idaho, May 19, 2022

Area Forecast Discussion
National Weather Service Pocatello ID
846 PM MDT Wed May 18 2022

.UPDATE...

NBM 4.1 shows northern portion of the advisory area actually
reaching criteria overnight so moved up the advisory in those
areas to start at 9z. The NBM 4.1 continues to support wind gusts
near warning levels and its probabilities support warning as well.
But the 4.1 can be a little hot in these types of situations so
think the advisory is better suited still. With that said blowing
dust will likely be a problem on I 15 north of Idaho Falls and
strong winds are very likely on I 84 around Yale Road. Refreshed
the winds for tonight into tomorrow morning and will allow the
current set of advisories to expire as winds this evening will
temporarily settle down.

13

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.PREV DISCUSSION... /issued 303 PM MDT Wed May 18 2022/

SHORT TERM (Tonight - Thursday)...
Elevated winds are in place this afternoon as ahead of a
deepening U/L trough across the Pacific NW. Wind advisory level
winds continue across the Arco Desert and portions of the Upper
Snake Plain and this will continue into the evening hours.
Afternoon satellite imagery shows increasing clouds across western
and northern Idaho associated with an approaching potent late-
Spring cold front. In this features wake, expecting high
temperatures Thu and Fri to be well below normal with highs
topping out only in the 40s and 50s. The bigger concern will be
for strong winds throughout the day tomorrow and a Wind Advisory
has been issued for a large portion of the forecast area tomorrow.
This event looks to be more of a "high- end" advisory level event
as it's very close to warning criteria. Considered a high wind
warning but NBM 4.1 and various model ensemble guidance kept
things just a tad shy of High Wind Warning levels (40 mph
sustained and/or wind gusts 58 mph). There will certainly be a few
more wind prone spots that do reach these levels, namely along
I-84 near Idahome and Yale and across portions of the Arco Desert
but it likely won't be as widespread, but again it's very close so
an upgrade is still possible. Regardless of the headlines in
place, Thursday is going to be quite windy for much of eastern
Idaho! Current wind forecast leaned heavily towards NBM 90th
percentile along with NBM 4.1 but again, winds stayed just below
criteria. Blowing dust will be a concern across portions of the
area, especially just north of Idaho Falls. As the front moves
through the region, light showers are expected as well mainly for
the northern Central mountains, Lost River range, and the Montana
Divide late today into Thursday. McKaughan

LONG TERM (Friday through next Wednesday)...
Models depict a positive-tilt trough extending from the High
Plains into southeast Idaho Friday morning. Most of the moisture
and jet dynamics are well to the south, leaving any chances of
precip coming from terrain influences. EFI is supporting strong
winds in the upper Snake Plain. Models indeed show a tight
gradient in that area with a down-valley flow. Nudged the winds
towards the NBM 4.1 solution, which is notably higher than the NBM
4.0. A second trough will drop in from the northwest on Saturday,
but we should only see an inch or so of snow accumulation in the
Central Mountains. We should once again see another trough drop in
from the northwest on Sunday with similar results. Both of the
troughs this weekend are well accounted for in the deterministic
models and about 3 of 4 ensemble clusters. These are fairly low
impact weather systems, but the entire forecast area will see
lower than normal temperatures over the weekend. The ensemble
clusters generally favor a low amplitude ridge to our west early
next week, but about 17% of the ensemble members (weighted heavily
towards the GFS) keep a trough lingering over the Great Basin by
Wednesday. Hinsberger.

AVIATION...
Winds continue to be the primary focus for this TAF package as a
cold front bears down on us from the northwest. Winds should
continue to increase through today as we reach peak heating, then
subside somewhat after sunset. This may be the best chances for
low-level wind shear at KSUN. Winds will quickly pick up early in
the morning. Ceilings should remain VFR as cloud bases lower ahead
of the front. There is little precip expected, but best chances
will be just after sunrise tomorrow at KDIJ. Hinsberger

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
Wind Advisory from 3 AM to 9 PM MDT Thursday for IDZ051>054-058-
062-063.

Wind Advisory from 6 AM to 9 PM MDT Thursday for IDZ055>057.

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