textproduct: Pocatello

KEY MESSAGES

- High avalanche danger continues in the backcountry of the Upper Snake River highlands and Sawtooth mountains.

- Break between storm systems today for most of southeast Idaho, with slightly warmer temperatures.

- Very wet and warm storm expected to arrive afternoon on Christmas Eve and last into Christmas morning.

UPDATE

Issued at 252 AM MST Tue Dec 23 2025

Looking at the next 24 hours or so today and tonight...no major trends or forecast changes are noted. This period will serve as a quiet break between systems aside from some lingering rain and snow showers this morning across the Central Mountains, and perhaps a few patches of fog. A modest warming trend also continues, with high temperatures reaching the mid-40s to mid-50s for most population centers today.

SHORT TERM /THROUGH THURSDAY/

Issued at 1212 PM MST Mon Dec 22 2025

A massive upper level low in the eastern Pacific will slowly shift eastward over the next 36 hours. This puts the current time in between storms, so as the current storm winds up in the eastern zones tonight, Tue is a break from rain and high level snow for most. But this break may at best last into the morning of Christmas Eve. The low sets up close enough to the coast to once again fling impulses of warm rain and high elevation snow through CA, NV, and finally into the southern Gem State. The exact timing of the worst rates of precipitation have a wide spread among the various deterministic guidance, but the worst generally will be the night time hours on Christmas Eve. So get your travel done on the night of the 23rd or get going early on the 24th. This low is so large that it has a massive fetch from the south, so the air will be mild with temperatures actually in a warming trend even with the return of clouds. There is some let up Christmas afternoon, but that is relative to the moderate to heavy precipitation the previous night.

Temperatures will peak Christmas Eve, with highs in the Snake River plain in the lower to middle 50s, with places like Stanley warming to around 40 to the middle 40s. For Christmas Day, afternoon highs only drop about 1 deg F for most locations. Cold air will wait for after this period.

Wind will stay in the breezy (10-20mph) to windy (20-30mph) category the entire time. Expect southerly to westerly so shouldn't have an issue with any sort of flash freezing, and nothing strong enough in this period to warrant an Advisory or Warning.

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

Issued at 1212 PM MST Mon Dec 22 2025

The massive low along the west coast will begin to lift and move inland early in this period. Warm moist air will continue to generate rain and high elevation snow on Thu night/Fri/Fri Night. The formerly closed low opens into a wave and all clusters time the 500mb trough to pass through Idaho longitudes on Sat afternoon. About 30 percent of the solutions have the flow splitting and doing little to eastern Idaho, but the remainder have the feature staying together and giving a final round of rain and snow Sat/Sat night. Once this trough is pushed eastward, a massive upper level ridge returns, shutting off the precipitation, and allowing for larger temperatures spreads from the morning low to the afternoon high, generally colder than it has been, with lows and highs much closer to climatic normals for the time of year; this means temperatures down 10 to 15 degrees for both highs and lows by Fri afternoon/Fri night. The wind remains moderate to high, with the strongest wind Fri afternoon through Sat, where Wind Advisory level strength is possible.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 428 AM MST Tue Dec 23 2025

A break between storm systems with VFR conditions is expected today, tonight, and Wednesday morning across southeast Idaho. This morning's airmass is quite saturated, so watching some BR and/or VCFG in/near KIDA and KPIH which is currently handled with TEMPO groups. Confidence is very low on any terminal getting "socked in", and OVC mid-level clouds might take the edge off any fog/low stratus organization as well.

PIH WATCHES/WARNINGS/ADVISORIES

None.