textproduct: Pocatello

KEY MESSAGES

- Mainly dry daytime today. Precipitation returns tonight and continues through Monday.

- Weather pattern remains active through Christmas week.

- Continued well above normal temperatures through Christmas. Slight cooling but still above normal next weekend.

SHORT TERM /THROUGH TONIGHT/

Issued at 129 AM MST Sat Dec 20 2025

Only very light snow showers in the mountains expected through sunset today. Another atmospheric river sets up tonight into Monday this time mainly coming from northern California. It's another very mild system with very elevated snow levels once again. May start out briefly as snow in low elevations later tonight with some 1 to 3 inch snow amounts in the Central Mountains and Sawtooth and Sun Valley regions through 5 AM. Today will be one of the cooler days in the forecast period with highs in the 20s to lower 30s mountains and mid 30s to lower 40s valleys. Lows tonight teens mountains and 20s to lower 30s valleys. After the very strong winds yesterday they will be more in the 10 to 20 mph range in the Snake River Plain through this afternoon.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 117 PM MST Fri Dec 19 2025

Our wet and breezy pattern continues to begin next week. We have another round of moderate to heavy precipitation moves in during the day Sunday, with the bulk of this round falling through Sunday night/early Monday morning. Some subtle differences will determine where heavier precipitation across the Snake Plain, Magic Valley and the South Hills/Albion Mountains. The slam dunk areas will be portions of the eastern and southeast highlands, and across the central mountains. The GFS favors the Magic Valley, southern end of the Snake Plain, and South Hills/Albion Mountains. The NAM shifts north to encompass the Lava Beds through the INL/Arco Desert into Idaho Falls northward. The ECMWF favors both depending on the time period you look at in the model. No matter where the band sets up, we are seeing signals for downslope along and south of the Snake River...and upslope into the central mountains and along the Montana border. In fact, this pattern is shaping up to provide the Wood River Valley and surrounding areas with a lot of moisture. The question will be snow levels. The official snow level forecast pushes them to 6000-7000ft across the central mountains and eastern highlands. Snow levels elsewhere push 7500-9000ft due to southerly flow and downslope effects. If you look at the low end range for snow levels...meaning how low they COULD be, we are seeing them 500- 1500 ft lower at times. While that shouldn't make a difference with snowfall in the lowest valleys, this could easily mean some spots getting a few inches or getting dumped on with a lot of wet, sloppy snow. Our latest forecast combining the Blend of Models and precipitation amounts from WPC, favored areas of precipitation, are looking at 0.50-1.5" of moisture. Higher elevations of the Big Holes/Bear River Range, Sawtooths and mountains surrounding Hailey/Ketchum are looking at 1.50-2.0". There is a 10-20% chance of exceeding 2" around Galena Summit. Even if we see a northward shift of the band across the Magic Valley and Snake Plain, there should be a "shadow" across portions of the Snake Plain with 0.10-0.50" worth of moisture falling. Looking at snowfall, where snow levels remain much higher across the Snake Plain and Magic Valley, we are seeing little to no snow. Where we can get snow to fall there, look for a couple of inches. Little to snow, for now, is forecast across the southern mountain valleys, Teton Valley, and the Challis/Pahsimeroi Valleys. Up to 5" is possible across Island Park and Stanley Basin. We have similar amounts for the Wood River Valley, BUT if snow levels end up 500ft or so lower...we could several more inches of wet snow falling. The current forecast puts most of the accumulating snow at/above 7000ft and in the 10-20" range for portions of the central mountains, Bear River Range, Big Holes and higher elevations surrounding Island Park. There is room for this forecast swing wildly in the next 24 hours, so please stay tuned to any changes coming even though most people may be out and about shopping or traveling to get an early holiday start. We need to let the current round of headlines expire before deciding on when and where we might need something for this round.

The moisture train continues into next week. Trends show things letting up on Monday and another band developing, but quickly shifting north on Tuesday. Christmas Eve, Christmas Day and the day after look wet. The chances for a white Christmas for lower elevations isn't good at all. IF we see snow for Christmas morning, it would be early and with this warm pattern continuing...it would melt pretty quickly. For a guaranteed white Christmas, you likely need to head well up into the mountains to find it. Lower elevation temperatures remain well above average throughout the extended forecast period with highs in the 40s and 50s...and places like Stanley, Copper Basin and Island Park above freezing in the afternoon. We aren't talking too much about wind, but this pattern really isn't giving a break at all from a lot of wind. Does that mean it will blowing every day at every location? No. The overall pattern though is indicative that a lot of places will see the wind off and on throughout next week.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 434 AM MST Sat Dec 20 2025

Expect MVFR ceiling at IDA to lift later this morning. Have it VFR by 18Z but think it could be earlier than that. DIJ has lifted to VFR. Other sites VFR with some mid ceilings. Expect rain showers to move into BYI, PIH and IDA between 08 and 12Z and dropped IDA to one thousand feet ceilings and BYI to MVFR. Brought snow into SUN and DIJ by 09Z with * Add discussion with MVFR to IFR ceilings expected.

PIH WATCHES/WARNINGS/ADVISORIES

None.