Hailey, Idaho 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

878
FXUS65 KPIH 191002
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
402 AM MDT Thu Jun 19 2025

...UPDATED AVIATION DISCUSSION...

.KEY MESSAGES...

- Warmest day of the week today with continued gusty winds.

- Shortwave trough moving in later today into Friday morning,
  supporting isolated showers and thunderstorms further north.

- Cold, Gulf of Alaska low moving in this weekend, helping to
  support continued gusty winds, precipitation chances further
  north, and a 20-30 degree cool down.

- Weekend system exits Sunday night as conditions turn warmer
  and drier for the work week next week.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 247 AM MDT Thu Jun 19 2025

Early morning satellite imagery shows a ridge axis of high
pressure shifting east over the Continental Divide as dry
conditions and clear skies prevail. Today is shaping up to be
the warmest day so far this year in many locations with highs in
the mid-80s to mid-90s or about 10-15 degrees above normal for
this time of year. With a forecast high in Pocatello of 95
degrees, today is expected to be our first 95 degree day since
August 19th 2024, or about two weeks ahead of our average first
95 degree day which is July 2nd. Our HeatRisk levels today for
afternoon highs will range from Moderate (2/4) to Major (3/4)
but given overnight lows in the 40s/50s/60s, this has kept the
overall HeatRisk impact levels in that Minor (1/4) to Moderate
(2/4) levels. As a result, have held off on any Heat Advisory
issuance given the limited duration of these well above normal
temperatures as a slightly cooler airmass builds in Friday.

A shortwave trough building in out of the west later today will
help to support isolated shower and thunderstorm development
further north this afternoon and evening into the overnight
hours and Friday morning. Best chances will remain confined to
the Central Mountains, Upper Snake River Plain, and Eastern
Highlands as predominant dry conditions continue further south.
This is support in the latest HREF model probability of thunder
through 6 AM Friday which shows a 10-50% chance in that
aforementioned area, highest further north in Lemhi, Clark, and
Fremont Counties. This shortwave trough is part of a much larger
and more organized Gulf of Alaska low pressure system that will
continue dropping south on Friday before moving inland this
weekend, helping to keep waves of moisture building into the
Central Mountains and Eastern Highlands throughout the day
Friday as dry conditions continue further south where a dry slot
becomes more well established. Temperatures on Friday will cool
about 5-15 degrees with highs in the 60s/70s/80s.

Winds will continue to remain elevated both Thursday and
Friday, peaking each afternoon. Strongest wind gusts today will
range from 30-45 mph, increasing on Friday to 35-55 mph, locally
stronger up to 60-65 mph. As a result, Lake Wind Advisories and
or Wind Advisories will likely need to be issued to capture
areas of strongest winds. Taking a look at the latest
probabilities of exceeding 50 mph gusts on Friday, the strongest
winds are expected to be out across the Arco/Mud Lake Desert,
east-Central Mountains, Clark County, and across the higher
terrain south of the Snake River Plain down into Utah where a
40-70% chance exists. These strong winds will help usher in a
much colder airmass this weekend. More on that below.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Issued at 247 AM MDT Thu Jun 19 2025

The weekend continues to look a LOT cooler, with the best
chance of precipitation occurring over the northern half of
eastern Idaho. This is due to a fairly strong, cold area of low
pressure dropping into portions of the Pacific Northwest and
Northern Rockies. Highs will be running 15-20 degrees BELOW
AVERAGE, with valleys only reaching the mid 50s to mid 60s.
Sunday morning, lows will be in the 30s for lower valleys and
teens/20s for the mountains. Light snow COULD fall down around
6000ft in the central mountains, under the center of this
low...but any accumulation along the Montana border and central
mountains should stay above 7000ft. Even then, totals are only
sitting in the 1-3" range. Slightly higher amounts are likely
across Lemhi County and southwest/western Montana. Totals for
Friday-Sunday in terms of rain or melted snow look to hit
0.10-0.33", with some higher ranges hitting closer to 0.50
across the central mountains. There is a 20-50% chance of more
than 0.50" in those same areas. Saturday looks pretty breezy, a
bit lower than Friday speed-wise. Heading through next week, we
do see the potential for a few showers and storms...mainly up
north again as we remain in an unsettled weather pattern. We
should much warmer temperatures and push back to ABOVE AVERAGE
by midweek.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 401 AM MDT Thu Jun 19 2025

We will remain VFR through the period. We will see a
gradual increase in terms of mid-level moisture. Do expect some
virga developing this afternoon and evening, with a slow increase in
the potential for sprinkles/light rain overnight. There is a non-
zero chance of thunderstorms as well. IF we see any impacts on TAF
sites, it most likely be SUN, DIJ, and IDA. The possibility is still
low enough to mention in each of those TAFs for now.

&&

.FIRE WEATHER...
Issued at 247 AM MDT Thu Jun 19 2025

Hot and dry conditions will continue today under the continued
influence of a broad ridge of high pressure ahead of a shortwave
trough building in this afternoon/evening. This trough will
help support isolated shower and thunderstorm development later
today into Friday morning in the Central Mountains, Upper Snake
River Plain, and Eastern Highlands as conditions remain dry
further south. Winds will remain elevated each day through the
weekend with a focus on today and Friday where a combination of
gusty winds and afternoon RHs dropping to the single digits,
teens, and 20s will lead to elevated fire weather conditions.
Taking into account the change in fuels conditions on the GB
Weekly Fuels Call yesterday to approaching critical for Idaho
FWZ 425 and 427 below 5500 feet, will be adding a headline
mention in the Fire Weather Forecast for South Central Idaho
Dispatch for gusty winds and low RHs. Keep in mind though
however that across the board, gusty winds and dry conditions
across much of our region will lead to broad elevated fire
weather conditions. As cooler temperatures build in the weekend,
expect higher afternoon RHs in the 20s/30s/40s for most,
50s/60s in northern FWZ 422/475/476 in the higher terrain.

Big changes are on the way Friday into the weekend where a Gulf
of Alaska low will move inland, helping to support several
waves of moisture into the Central Mountains and Eastern
Highlands, continued gusty winds, and a significant cool down of
20-30 degrees for Saturday and Sunday. Given the cooler airmass
building in this weekend and snow levels dropping to around
6000-7000 feet, we are looking at the potential for light
accumulating snow in the Central Mountains and Eastern
Highlands. Precipitation totals with this event through the
weekend will remain generally confined to Idaho FWZ 411, 422,
475, and 476 as all other zones end up in a dry slot and
receive little/no precipitation. In those aforementioned areas,
we are still looking at 72-hour totals Friday through Sunday of
an elevation dependent 0.10-0.50" with locally higher totals in
Lemhi County around 0.25-0.75", perhaps 0.75-1.00" across
highest elevations. Mountain snowfall will be in that T-3"
range, locally higher around 3-6" in N/NE upslope regions.

Looking ahead towards next week, this weekend system still
remains on track to move out Sunday night as a warmer and drier
airmass builds in for the work week next week outside of
isolated mountain showers and thunderstorms each afternoon.
Temperatures will also return to a warming trend as conditions
trend predominantly dry regionwide.

&&

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

&&

$$

SHORT TERM...MacKay
LONG TERM...Keyes
AVIATION...Keyes
FIRE WEATHER...MacKay