166 FXUS65 KPIH 220405 AFDPIHArea Forecast Discussion National Weather Service Pocatello ID 1005 PM MDT Sun Sep 21 2025
.KEY MESSAGES...
- Showers and thunderstorms continue through tomorrow
- Moderate to heavy rainfall is possible along with gusty winds
- Warmer temperatures return starting Tuesday
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.SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 119 PM MDT Sun Sep 21 2025
Our main area of low pressure along with locally heavier rainfall and storms continues to shift into western Wyoming this afternoon. In its wake, more showers and storms are developing as sunshine is producing enough instability to kick things off. Within the main area moving into Wyoming and any stronger storms elsewhere, moderate to locally heavy rain is possible. There is a 30-70% chance of wind gusts over 35 mph today, with peak gusts POSSIBLY hitting 45-50 mph. The best chance of stronger winds is across the south and in the central mountains. This secondary area of showers and storms actually will consolidate into a more widespread area of rain with embedded thunderstorms tonight east of I-15, as a stronger area of low pressure develops as it drops southeast across the Divide. That band quickly into Wyoming tomorrow morning, with some lingering showers and a possible thunderstorm across the eastern and southeast highlands. By tomorrow night, things continue to clear out. Cooler temperatures are on tap for Monday and Monday night. The potential for warmer spots to top out above 70 is pretty slim for highs. Tomorrow night, colder spots dip into the 20s and 30s. If trends continue, a FROST ADVISORY is not out of the question for the upper end of the Snake Plain.
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.LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 119 PM MDT Sun Sep 21 2025
We should see a mostly dry stretch of weather heading into next weekend. The models are struggling on what to do with another low as the ridge breaks down over the western U.S. The ECMWF keeps it farther south and brings little moisture, even in the form of clouds, our way later in the week. The GFS remains steadfast with a farther north track, which could gives us a lot more clouds and some possibility for light precipitation. Our Blend of Models continues to dry things out, or at least drop the chance of any moisture falling closer to 10%. Warmer temperatures will be back, especially if we can keep clouds out of here. The potential for highs starting with an "8" is increasing toward mid to late week.
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.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/... Issued at 1005 PM MDT Sun Sep 21 2025
The better organized storms are beginning to move east. Models are still indicating some isolated convection during the overnight hours. So will continue to mention VC wording at many TAF sites. Expect clearing during the day on Monday. NAM is trying to develop some isolated showers during the afternoon that could affect IDA/DIJ, but its not supported by other models. So will continue with a SCT wording with no weather for now.
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.FIRE WEATHER... Issued at 119 PM MDT Sun Sep 21 2025
Area of showers moving through the East Idaho district early this afternoon will give way to more showers and thunderstorms. Precipitation continues overnight as frontal boundary moves through the state, and can`t completely rule out an additional thunderstorm. Temperatures Monday remain cool, generally in the 60s for lower elevation locations, then slightly warmer into the lower 70s for Tuesday. Upper ridge builds back into the region for most of the week, allowing temperatures to climb back above normal by mid to late week. Model means flatten the ridge ahead of a system cutting into the Great Basin from the California coast late in the week, but there is still a lot of model spread regarding how fast the ridge breaks down.
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.PIH WATCHES/WARNINGS/ADVISORIES... None.
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SHORT TERM...Keyes LONG TERM...Keyes AVIATION...13 FIRE WEATHER...DMH
NWS PIH Office Area Forecast Discussion