792
FXUS65 KPIH 272328
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
528 PM MDT Thu Aug 27 2026

.KEY MESSAGES...

- Marginal risk of severe thunderstorms in the southeast
  highlands today. Isolated thunderstorms forecast this
  afternoon and evening, and again Friday.

- Appreciable rainfall expected Friday and Saturday across much
  of the area.

- Today is the last hot day for a while. Strong cooling from
  today to Friday. Humidity trends higher.

&&

.DISCUSSION...
Issued at 147 PM MDT Thu Aug 27 2026

Showers and thunderstorms have been ongoing for most of the day and
continue early this afternoon. Much of southern and southeastern
Idaho is included in the "Marginal" risk today from the SPC outlook.
The main threat will be wind gusts around 60 mph. It appears most of
this activity will be wrapped up around 9-10 PM tonight with the
next round of showers arriving early Friday morning. This Pacific
moisture is being funneled into our area from a combination of an
area of high pressure over New Mexico and western Texas and an area
of low pressure over northern Washington. Previous model runs wanted
to bring the low a bit farther south into nearly central Idaho,
though now it is staying just a bit farther north. Not a significant
change, but one to keep watching. A track farther south could
continue the trend of cooler temperatures and slightly increased
precipitation. Even with this slightly "northern" track, we can
still expect cooler temperatures overall and some measurable
rainfall for much of the area. PWATs beginning Friday afternoon will
be pushing 0.80-1.10" and a wetting rain is expected with these
storms on Friday and especially on Saturday. Isolated thunderstorms
return for Friday afternoon with a little break before another round
of widespread showers overnight Friday into Saturday morning.
Uncertainty lies within how strong afternoon convection will be
either day based on how well the atmosphere is worked over in the
morning and how long it will have to "recover."

As the area of low pressure moves eastward during the weekend, it
will take the precipitation with it. By Sunday afternoon, any
leftover activity will be more confined to the Eastern Highlands.
Looking at 48-hour precipitation amounts ending Sunday morning, the
NBM shows about a 30-40 percent chance of at least a quarter inch of
rainfall for areas like Burley, Carey, Arco, to Fort Hall. This may
be a bit overdone, but at least a tenth of an inch seems likely for
much of the area. Precipitation amounts increase farther east you go
with a 60 to 80 percent chance of at least a quarter inch of
rainfall for the bulk of the Central Mountains and the Eastern
Highlands. There`s about a 30-50 percent chance of at least a half
inch of rain from Stanley to Hailey and about a 60 to 70 percent
chance of the same from Preston to Victor to Island Park.

High confidence remains in falling temperatures with today being the
last day we see highs in the upper 80s to low 90s for a bit. By
Friday afternoon, highs will be nearly 10 degrees cooler before we
drop into the 70s for most on Saturday and low to mid 70s on Sunday.
We`ll be back into the upper 70s and low 80s by Monday and Tuesday,
but it won`t be quite as quick of a warm up as we`ve seen lately.
Look for wind gusts to pick up on Saturday and Sunday, too, even
outside of thunderstorm activity. Gusts will range from 25 to 35 mph
each afternoon.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 501 PM MDT Thu Aug 27 2026

Have prob30 thunderstorm groups at all sites other than SUN
through 02 to 03Z this evening. That will be the main impact
with showers or vicinity showers continuing overnight into
Friday morning. Expect thunderstorms Friday afternoon as well
and have included prob30s once again at all sites after 20Z.

&&

.FIRE WEATHER...
Issued at 147 PM MDT Thu Aug 27 2026

Isolated thunderstorms continue once again this afternoon with a mix
of wet and dry storms. We had one storm pass directly over the
office this morning which brought 0.15-0.20" of rainfall with it.
This is just a taste of what is to come! Storms today will be
capable of producing gusty winds of 50-60 mph with a "Marginal" risk
for severe weather from the SPC outlook over much of southern and
southeastern Idaho. We`re looking at Pacific moisture being funneled
into Eastern Idaho over the next few days as we are sandwiched
between high pressure over New Mexico and western Texas and an area
of low pressure over northern Washington. So, while storms will be
increasing in coverage for Friday and Saturday into the nearly
scattered to scattered categories, we are expecting wetting rains
across much of the area. You can find some specific precipitation
probabilities in the discussion above, but it appears that much of
the area will see at least a tenth of an inch of rainfall from
Friday morning to Sunday morning with higher 48-hour totals
approaching a half an inch in the higher elevations of the Central
Mountains and Eastern Highlands. The main uncertainty lies with how
well morning showers work over the atmosphere on Friday and Saturday
and potentially limit thunderstorm coverage in the afternoons. We
have high confidence in quite the cool down with this system, too.
Highs will fall almost 10 degrees by Friday afternoon and highs will
be in the mid to upper 70s Saturday and low to mid 70s on
Sunday.

&&

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

&&

$$

DISCUSSION...AMM
AVIATION...GK
FIRE WEATHER...AMM