163 FXUS65 KPIH 131957 AFDPIHArea Forecast Discussion National Weather Service Pocatello ID 157 PM MDT Sat Sep 13 2025
.KEY MESSAGES...
- Cooler temperatures continue into early next week.
- Isolated showers and thunderstorms also continue, mainly over higher terrain.
- Drier and slightly warmer pattern for mid to late next week.
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.SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 157 PM MDT Sat Sep 13 2025
Satellite imagery shows East Idaho remains under the influence of amplified but slow moving upper trough, with axis draped along the Wyoming border. Vis imagery shows shallow cu field across most higher terrain areas, but weak convective development has already begun along the Wyoming and Utah borders. High-res models maintain mainly isolated to widely scattered convection this afternoon and early evening in these areas, but also weak isolated development expected in the central mountains. Small hail and gusts 35-40 mph remain possible. Convective expected to dissipate with loss of daytime heating by mid evening. Weak transitory ridge overnight into mid-day Sunday expected to keep any additional convective activity at bay. Sunday should be the warmest day under ridge axis, but next shortwave feature currently visible off WA/OR coast expected to arrive late day. Next round of showers and thunderstorms expected to begin Sunday afternoon across the central mountains and potentially Magic Valley and South Hills. Showers then spread northeast late afternoon and evening for the rest of the region. There is some uncertainty in the details, but still enough of a threat to maintain isolated to scattered coverage forecast across most of the region for the evening and overnight.
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.LONG TERM /MONDAY THROUGH FRIDAY/... Issued at 157 PM MDT Sat Sep 13 2025
Meteorologically, fall arrived on September first. Astronomically, it arrives on the 22nd. Practically speaking, we get a real taste of it on Monday. Highs will be in the 60s for most with partly cloudy skies and rain showers for at least the higher elevations of the Central Mountains and Eastern Highlands as an upper level low passes through Idaho. As far as precipitation goes, the NBM shows about a 10 to 20 percent chance for at least a tenth of an inch of QPF on Monday for the Snake River Plain and that increases to about a 30 to 50 percent chance for parts of the Central Mountains and Eastern Highlands. It will be a bit breezy on Monday, too, with gusts around 20 to 25 mph. Tuesday, Wednesday, and Thursday look like dry days as high pressure builds back in over the area and we begin to warm into the low and mid 70s Tuesday, mid to upper 70s by Wednesday, and finally reach the upper 70s and low 80s on Thursday. The longer range models are hinting at another system potentially heading our way for next weekend, but that`s way too far out to get into any specifics just yet, though it may at least bring another slight cool down.
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.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1121 AM MDT Sat Sep 13 2025
Storms look to be even more isolated in nature this afternoon than the last few days. So, while a shower or storm may pass near a terminal, confidence is low in a direct impact. Will include some VCSH in the TAFs for DIJ and SUN, but that`s all for the time being. Otherwise expect VFR conditions today and Sunday. Winds remain light through the rest of today and tonight. Look for clear skies tonight before our next round of cloud cover begins to move in Sunday morning ahead of our next system.
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.FIRE WEATHER... Issued at 157 PM MDT Sat Sep 13 2025
East Idaho remains under the influence of the slowly exiting upper trough this afternoon. Mainly isolated showers and thunderstorms expected into the evening across higher terrain, with small hail and gusts up to 40 mph. Transitory ridge of high pressure moves across the region tonight and early Sunday with dry conditions expected. Sunday should see a warm up of a few degrees under the influence of the ridge, but the dry conditions are short-lived as the next system arrives Sunday afternoon. Showers and thunderstorms return to the western portions of the East Idaho fire district during the afternoon, spreading across the remainder of the region through the evening and overnight. Isolated to scattered showers and thunderstorms remain forecast for most areas through the day Monday. Monday should also be cool with daytime highs only in the 60s or lower 70s for most lower elevation areas. By Tuesday, a new ridge of high pressure sets up for a return to dry conditions through Thursday. Temperatures rapidly return to the mid 70s to lower 80s for most of the region. The ridge begins to break down by the weekend, with some moisture and potential showers and thunderstorms returning as early as Friday.
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.PIH WATCHES/WARNINGS/ADVISORIES... None.
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SHORT TERM...DMH LONG TERM...AMM AVIATION...AMM FIRE WEATHER...DMH
NWS PIH Office Area Forecast Discussion