213
FXUS65 KPIH 172318
AFDPIH

Area Forecast Discussion
National Weather Service Pocatello ID
518 PM MDT Tue Jun 17 2025

.KEY MESSAGES...

- Much hotter by Thursday.

- Windy on Friday, then breezy and turning much cooler for the
upcoming weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 130 PM MDT Tue Jun 17 2025

Weak ridge of high pressure beginning to build into East Idaho.
Satellite imagery shows weak afternoon build ups mainly over higher
elevations and the Upper Snake River Plain. Most of the convection
should remain east of the forecast area, though would not be
surprised to see a weak shallow shower or two over the Island
Park/Yellowstone region this afternoon/early evening. Temperatures
are slightly cooler today behind this trough, but rebound back into
the mid/upper 80s for Wednesday.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 130 PM MDT Tue Jun 17 2025

Upper ridge axis overhead for Thursday, which should be the hottest
day of the week. Highs still look to reach the lower/mid 90s across
most lower elevation areas. Did nudge temperatures up a degree or
two from the deterministic NBM, just slightly above the 50th
percentile. Could see an increased chance of showers/isolated
thunderstorm across the Island Park/Divide region late Thursday, but
most of the moisture impacts should remain north across Montana.
Deep closed low still expected to reach the PacNW coast early
Friday. Strong 700mb jet with deep mixing in place for Friday and
Saturday ahead of the main low, increasing winds across the central
mountains and northern portions of the Snake Plain. First surface
front drives through late Friday, followed by second front mid day
Saturday. Have slightly increased winds above NBM means for both
afternoons, and Wind Advisory and/or Lake Wind Advisory may be
needed. Temperatures begin a significant slide through the weekend,
especially compared to Thursday`s highs. Isolated to scattered
showers and thunderstorms will be possible both days, mainly across
the north half of the forecast area. East Idaho remains under
influence of trough axis to the west Monday into Tuesday.
Temperatures rebound from the weekend lows under influence of
southwest flow aloft.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 514 PM MDT Tue Jun 17 2025

No aviation impacts expected through Wednesday afternoon and
early evening. Generally clear skies or only few to scattered
high clouds. Winds may increase to the 10 knot range Wednesday
afternoon especially at BYI, PIH and IDA. Up and down valley
diurnal wind shifts at SUN but generally 10 knots or less.
Overall pretty good flying weather can be expected.

&&

.FIRE WEATHER...
Issued at 130 PM MDT Tue Jun 17 2025

Best chances for showers and thunderstorms continue to shift further
east as high pressure begins to build in over the West, with around
a 10 to 25 percent chance in Fire Weather Zone 411 and the eastern
extent of Zone 410 this afternoon. Winds will be breezy this
afternoon across south-central ID, where gusts will reach up to
around 25 mph. Minimum relative humidity today will range 15 to 25
percent across much of the area, with higher values up to around 35
percent in the highlands and mountains. These values will continue
to decrease over the next several days as high pressure strengthens
overhead. A pattern change will arrive this weekend with the primary
impacts for Southeast Idaho looking to be wind and much cooler
temperatures compared to the rest of this week.

&&

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

&&

$$

SHORT TERM...DMH
LONG TERM...DMH
AVIATION...GK
FIRE WEATHER...Cropp