739
FXUS65 KPIH 081718
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
1118 AM MDT Tue Sep 8 2026

.KEY MESSAGES...

- High pressure will keep skies nearly clear and a warming trend
  to temperatures through Thursday.

- A trough approaching from the northwest will increase wind on
  Thursday afternoon, allowing humidity and wind to combine to
  potentially bring critical fire weather conditions.

- Next chance of precipitation and risk of thunderstorms could
  be as early as Friday.

&&

.DISCUSSION...
Issued at 201 AM MDT Tue Sep 8 2026

Today through Fri...A weak trough moving through western MT
will bring only a slight chance threat of showers and
thunderstorms to the upper Snake River highlands. By this
evening, the trough is well east of the forecast area. West
northwest flow continues Wed and shifts during the day Thu to
more westerly. As the next trough approaches from western
Canada, the gradient tightens on Thu and has the potential to
reach just below Wind Advisory criteria on both Thu and Fri
afternoons.

500mb heights rise the next two days, allowing some significant
warming. The trough approaching for Fri should spread some
clouds and bring in cooler air aloft, which should eventually
bring cooler temperatures at the surface, likely on Fri.

Fri night through Mon...A low breaks off the trough, perhaps as
this scenario is not featured in every solution cluster. This
shifts the airflow to a southerly component that draws up
subtropical moisture, as well as bringing some available
moisture itself. This brings a risk of showers and thunderstorms
to the forecast area. First, for the southern and eastern
highlands, then on Sun, as the closed low moves through central
and northern Idaho, to the central Idaho mountains. None of it
appears very heavy, but it should be unstable enough to trigger
thunderstorms. Strong wind possible Sat night/Sun morning as the
low pushes through the northern half of the forecast area.
Temperatures should sink to near to below normal for this
period, with the coldest temperatures just after trough passage
on Sun.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1116 AM MDT Tue Sep 8 2026

No aviation impacts expected through Wednesday morning. Clear
skies through the period with afternoon wind increases to the 10
knot range at all sites with some gusts up to 20 mph at PIH and
IDA.

&&

.FIRE WEATHER...
Issued at 201 AM MDT Tue Sep 8 2026

Warming and drying return today and continues through at least
Thu afternoon. This will drive some low elevation humidity
readings below the 15 percent critical threshold today, then
becoming more widespread Wed and Thu. An approaching trough will
increase the wind on Thu afternoon to exceed critical thresholds
for both mountains and plains, so it is very likely Red Flag
Warnings will be needed for Thu. Overnight, the approaching
trough may keep the wind elevated, but it will also bring higher
humidity for Fri. At least, it is expected. Showers and
thunderstorms should return Sat and Sun as the trough traverses
the northern half of the forecast area. The source region would
indicate dry thunderstorms, and current forecasts would be for
isolated coverage.

&&

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

&&

$$

DISCUSSION...Messick
AVIATION...GK
FIRE WEATHER...Messick