429
FXUS65 KPIH 300427
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1027 PM MDT Fri May 29 2026

.KEY MESSAGES...

- Increasing clouds this afternoon with isolated thunderstorms.

- Wet weather arrives by Saturday for parts of east Idaho.

- Chilly weather over the weekend into early next week.

&&

.DISCUSSION...
Issued at 134 PM MDT Fri May 29 2026

Satellite imagery shows two distinct circulations within
incoming upper trough - one over SE Oregon and one over central
Nevada. Nevada circulation shifts northeast into Utah overnight
tonight, with Oregon feature moving into western
Idaho/panhandle. High-res models still produce mainly isolated
convection late this afternoon into this evening across portions
of East Idaho. Main precipitation begins during the overnight
across the southeast. Wrap-around moisture shifts ahead of the
southern low, ahead of main trough axis during the day Saturday.
Heaviest precipitation is still expected to lie along/northeast
of a line roughly from Challis/Stanley to Bear Lake. Southwest
of that line, tight gradient from wetting rains to nothing is
forecast. Higher elevations across the eastern highlands should
see the highest rainfall totals, trending highest to the
northeast corner, where totals through Sunday could approach or
exceed one inch before the trough exits. Temperatures cool into
the 60s under the influence of the low for both Saturday and
Sunday. Breezy winds are expected, and we may see speeds bump up
against the lower thresholds for a LAKE WIND ADVISORY on
American Falls Reservoir.

Trough axis shifts north into Montana late Sunday into Sunday
night, but general troughiness lingers into the early part of
the week. Lingering rainfall along the Divide late Sunday
dwindles through the night, leaving dry conditions across East
Idaho. Temperatures should be at their coolest Sunday night, and
there are still expectations for portions of the Snake Plain to
flirt with FROST ADVISORY conditions with lows around or just
below 36 degrees, but remaining above freezing. Could see a few
showers return during the day Monday under the influence of
continued broad trough across the PacNW, but most of the region
should remain dry. Operational GFS/ECMWF both push a weak
shortwave through the flow in the Wednesday/Thursday time frame,
but these appear to be outliers compared to most of the ensemble
solutions. Current forecast remains dry for most areas at this
time.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1012 PM MDT Fri May 29 2026

TAFs have overall trended worse with the next feature that
begins its approach in a few hours. The TAFs are quite disparate
in conditions, so it will be best to take them one at a time,
starting with the easiest.

KBYI main forecast problem is wind. Moderate to strong wind
expected, staying nearly entirely out of the west, with a peak
of G30KT starting around 30/08Z and continuing until early
afternoon. No precipitation, and almost no CIGs expected, and
no impacts to VSBY.

KSUN. Typical downslope wind staying light to moderate with no
CIG until possibly with TSRA develop, starting around 30/18Z.
TSRA will bring CIG to 6000ft AGL or so. TSRA ending around
31/02Z, so moderate downslope resumes with some low clouds,
depening on how much moisture is dropped in the Wood River
valley from this event.

KPIH. The most difficult forecast as this region is on the
fringe of the bad weather. SHRA on and off and not expecting
TSRA in this area at all. By 30/14Z, expecting marginal VFR due
to CIGs and VSBY in some BR. By 30/19Z temperatures will have
warmed enough to evaporate the BR and keep CIGs low but solid
VFR. Wind only gusty late tonight, G30KT, but by the time the
airdrome opens, G20KT or so is the most expected.

KIDA. Ugly. SHRA/BR with plenty of marginal VFR expected
starting 30/12Z. By 30/19Z, add TSRA to the mix. This will
include a risk of VSBY going to IFR conditions in the TSRA, even
in the afternoon. Wind is gusty tonight, and just plain erratic
in direction and elevated, but not really gusty during the day.

KDIJ. SHRA starts up again around 30/11Z. Plenty of marginal VFR
for CIGs and VSBY, then by mid morning IFR conditions as it just
continues to rain and rain. This is both CIG and VSBY. There is
even a risk of TSRA starting 30/21Z. Outside of TSRA, wind is
nor much of a factor here.

&&

.FIRE WEATHER...
Issued at 200 AM MDT Fri May 29 2026

An approaching low pressure system will bring increasing clouds
this afternoon. This will produce cooler temps and slightly
higher humidity this afternoon. A few isolated dry thunderstorms
are possible this afternoon and evening. Gusty erratic winds
are possible near storms. Much cooler weather with higher
humidity is likely for Saturday. Wetting rains are likely for
much of Salmon-Challis and East Idaho on Saturday, but not so
much for South Idaho.

&&

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

&&

$$

DISCUSSION...DMH
AVIATION...Messick
FIRE WEATHER...13