Mackay, Idaho Weather Forecast Discussion

985
FXUS65 KPIH 091733
AFDPIH
Area Forecast Discussion
National Weather Service Pocatello ID
1133 AM MDT Tue Sep 9 2025
.KEY MESSAGES...
- Isolated to scattered showers and thunderstorms much of the
  week.
- Cooling trend, with highs 5 to 10 degrees below climatological
  norms by late week.
&&
.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 338 AM MDT Tue Sep 9 2025
Low pressure situated along the OR/CA coast today will result in
increased moisture into Southeast Idaho in Southwest flow. Radar
shows showers shifting into central and southeastern Idaho early
this morning. The 24-hour precipitation forecast is 0.10" across the
northern half of the CWA with 0.25" to 0.50" across the central
mountains. Locally higher totals will be possible with stronger or
training storms. HREF probability of thunder indicates a 10 to 30
percent chance of isolated thunderstorms across portions of
Southeast Idaho from just before sunrise to around 1 PM MDT. Chances
from then through the evening increase to 20 to 70 percent across
the central mountains, increasing further north, and 20 to 50
percent chance across the eastern highlands and upper Snake River
Plain. Stronger storms will be capable of producing wind gusts to
around 40 mph and small to moderate hail.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Issued at 143 PM MDT Mon Sep 8 2025
Unsettled pattern continues through the week, though models have
started to consolidate precipitation mainly over the higher
elevations with less coverage through the Snake Plain. This may be
due to pulling drier air between weak shortwaves rotating around the
upper low. Development and progression of convection throughout the
week will also have significant input to how much QPF falls over any
particular location. As such, long term estimates of the
precipitation should be taken with a dose of skepticism this far
out. Temperatures remain cool, with highs generally in the 70s for
many lower elevation locations. Once the upper trough shifts east
for the weekend, there is still a potential for wrap around showers
to occur especially Saturday. Temperatures remain cool with ensemble
means dropping daytime highs to the mid to upper 60s for portions of
the Snake Plain, and lows generally in the 40s.
&&
.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1125 AM MDT Tue Sep 9 2025
Showers are already ongoing this morning around parts of Eastern
Idaho and coverage is expected to increase throughout the day. A few
isolated storms are popping up around PIH and moving north, so have
added in a PROB30 at IDA for this afternoon/evening and kept the
other PROB30s at DIJ and SUN as previously forecast. Most of these
storms will produce wind gusts around 35 kts, but a rogue gust near
45 kts can`t be completely ruled out. The NAM wants to continue some
activity overnight into early Wednesday morning, but uncertainty is
high so will leave any mention out of the TAF for PIH and IDA for
now. Thunderstorm activity on Wednesday afternoon looks a bit more
isolated in nature and outside of most of our TAF sites.
&&
.FIRE WEATHER...
Issued at 143 PM MDT Mon Sep 8 2025
Dry day continues through this evening in between systems. Next
round of moisture shifts into the region after midnight with showers
developing across the southwest half of the district, shifting
northeast through the day Tuesday. Although chances are low
overnight and early Tuesday, there is potential for a thunderstorm
or two, and chances increase into the afternoon and evening. This is
the beginning of a broad period of unsettled conditions for the
week. Daytime humidities are expected to remain above critical
thresholds throughout the week. Precipitation amounts remain
variable, with the Snake Plain expected to remain the driest overall
compared to higher elevations. Thunderstorm activity could provide
periods of locally heavy rainfall. The deep Pacific trough shifts
east by the weekend, but moisture could linger for continued
isolated to widely scattered showers and thunderstorms both Saturday
and Sunday.
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Cropp
LONG TERM...DMH
AVIATION...AMM
FIRE WEATHER...DMH

NWS PIH Office Area Forecast Discussion