Wind Advisory 18, NWS Pocatello, ID

Area Forecast Discussion
National Weather Service Pocatello ID
146 PM MDT Sun Jun 18 2023

.SHORT TERM...Tonight through Monday night. Surface cold front
marching through East Idaho today. Winds above Wind Advisory
threshold across the Arco Desert this afternoon, so will leave the
headline in place. Have a couple other sites that are borderline,
but generally not representative of a zone, so will hold off on
other headlines. Two lines of showers over the region, slowly
shifting east. First over the eastern highlands where frontal
forcing and orographics have combined. Second still spread from
Southwest Idaho across Snake Plain edge of Central Mtns to the
Divide, slowly shifting east ahead of shortwave axis and behind
surface front. Western band continues to sage southeast behind the
front remainder of this afternoon and evening. Precipitation in
orographic upslope region in the northeast corner briefly enhances
with this second feature, before gradually weakening as front
reaches the southeast corner and stalls near Bear Lake tonight. A
few thunderstorms will be possible with gusty winds and small
hail. Frontal boundary retrogrades north again early Monday as
mid level 700mb flow strengthens over Nevada ahead of trough axis
and second cold front. NAM portrays solid dry slot over western
half of forecast area during the day Monday, but GFS holds on to
broad area of showers across the Central Mountains. Band of
precipitation over southeast corner intensifies ahead of second
cold front through the day before gradually weakening overnight
Monday night. Winds again on Monday look breezy to windy most
areas, and may be close to Wind Advisory criteria once again for
the Arco Desert, though current forecasts remain just below
thresholds. Temperatures turn colder Monday night, but the coldest
air behind these fronts arrives after the Short Term period. DMH

.LONG TERM...Tuesday through next Sunday. We continue to watch a low
across the Pacific Northwest slow lift northeast Tuesday and
Wednesday. Gusty winds will linger Tuesday, but mainly across the
central mountains, Arco Desert and eastern highlands. They don't
look quite as strong as today or Monday, so it doesn't look like we
will need any wind headlines. Showers and storms will also persist,
especially across the north Tuesday and only across the north
Wednesday. Tuesday and Tuesday night still look like the coolest
period. Highs Tuesday will only be in the 50s and 60s in the
valleys, with 30s and 40s for the mountains. For Tuesday night, most
mid and upper slope locations will be below freezing. In the Snake
Plain and Magic Valleys, we should drop into the mid 30s with a few
spots possibly dropping to 30-32 degrees. Frost conditions are
possible, especially across the Arco Desert and Upper Snake Plain.
Low pressure reloads to our southwest before swinging back north
across Idaho Friday. Spotty showers and storms are possible
Thursday, with a much better chance on Friday. It could be
interesting in terms of strength of storms as they could be more
intense, especially if we have a slower arrival of that low. High
pressure tried to build back in next weekend, but moisture will be
around for some potential of rain and thunder. Highs will quickly
warm back up after midweek. Keyes

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.AVIATION...Pockets of showers with possible isolated storms will
remain through Monday. At the moment, we are covering that in the
TAFs with VCSH or -SHRA. The potential for storms is just high
enough for including a mention at DIJ, but cloud cover is really
keeping that chance down. We have seen sporadic MVFR/IFR conditions
this morning.  We keep that out of the forecast except at DIJ where
the possibility of lower ceilings may be higher overall. Keyes

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.HYDROLOGY...Some pretty decent rainfall overnight and this morning
has led to some rapid rises on a few rivers and creeks in the
central mountains. We did issue a FLOOD WARNING for the Big Lost at
Howell as it quickly rose to flood stage this morning and should
remain there until later tomorrow night/Tuesday morning. The Big
Wood at Hailey and a couple of surrounding creeks/rivers also are
following the same trend, but based on feedback from local
officials...it appears widespread issues aren't likely so we didn't
issue anything in that area. We maintain the headlines for Antelope
Creek and the Portneuf at Topaz. The heavier rain will be ending
across the central mountains today, and shifting into areas along
and east of I-15 tomorrow and early Tuesday. WPC is maintaining a
MARGINAL RISK for excessive rainfall today and Monday, but some far
it is steady(albeit heavier) rain vs showers/storms with very high
rainfall rates.  Later this week, we may need to watch the Henrys
Fork and Teton Rivers to see if we get any type of bigger response
to the rainfall happening in the next 36-48 hours. Keyes

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.PIH WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM MDT this evening for IDZ052.

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