FXUS65 KPIH 070824

AFDPIH



Area Forecast Discussion

National Weather Service Pocatello ID

224 AM MDT Mon Apr 7 2025



.KEY MESSAGES...



- Very high elevation snowfall the next 48 hours in the central

  Idaho mountains, light snow in the upper Snake River highlands



- Very windy conditions with blowing dust in the Snake River

  plain on Tuesday and Wednesday afternoons and evenings.



- Much colder Tuesday, with warming returning Wednesday.



&&



.SHORT TERM /THROUGH WEDNESDAY/...

Issued at 138 AM MDT Mon Apr 7 2025



Trough will swing through southern Idaho today and tonight, but

the trend in the southern half of the forecast area is for 

lesser snowfall with precipitation also trending lighter. Snow 

accumulation limited to areas in passes in the northeast 

highlands, and 8000ft elevation or higher in the central Idaho 

mountains. A second shortwave trough pushes through Tue/Tue 

Night, but there is even less of a threat of precipitation. By 

Wed, PoP currently runs down to zero or near-zero for the 

entire forecast area. 



Storm total rainfall doesn't get above 0.10 of an inch in the 

Snake River plain until north of Rigby. The main focus for 

rainfall will be in the western half of Custer County, including

the Wood River Valley and Stanley basin, where storm total 

amounts through Tue night are 0.10 to 0.30 in the valleys and up

to 0.80 of an inch in the mountains on the very western edge.

 

Even Galena summit will only receive 1 to 2 inches of snow with 

rain on either side of the snow period, so it is doubtful if 

much will remain with highs in the 40s both today and Wednesday.



There is a risk of thunder in the unstable air behind the front, but 

for today it will be limited to the western edge of the forecast 

area. On Tue, it will shift to the northeast corner, staying north 

and east of Roberts.



Expecting a warm day today, but the trough will bring in cold air 

and cloudiness, so expect a strong cool-down of 12 to 18 deg F to 

the afternoon high on Tue compared to Mon. The clear skies Wed will 

allow the return of warmer temperatures for the afternoon. 

Temperatures will get below freezing for the Snake River plain Wed 

night. 



Instability being forecast, the strong wind supporting the 

trough in the higher altitudes will be able to mix down both Tue

and Wed. This will likely mean Wind Advisories for the Snake 

River plain and possibly the valleys to the south of the Snake 

River. This includes a threat of reduced visibility in blowing 

dust--typical this time of year.



&&



.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...

Issued at 222 AM MDT Mon Apr 7 2025



High pressure will control the upper-level pattern again come 

Thursday, with models suggesting daytime highs will climb to 20 or 

more degrees above climatological norms across our lower valleys on 

Friday. We have blended the deterministic National Blend with the 

75th percentile to begin nudging highs closer to daily means on 

Thursday, Friday, and Saturday. Confidence is increasing in many low-

elevation areas across Southeast Idaho observing record-breaking 

temperatures during this period, especially on Friday during peak 

warmth.



The ridge axis will shift directly overhead on Friday and continue 

shifting eastward as the next upper-level trough works into the 

Pacific Northwest late week. Precipitation chances will reach 

southern Idaho on Saturday and likely persist through Sunday as the 

trough axis swings through. However, 500 mb ensemble clusters 

suggest much uncertainty in the upper-level setup come mid-weekend

into early next week, so confidence remains low in the forecast

through this timeframe.



&&



.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...

Issued at 1052 PM MDT Sun Apr 6 2025



VFR conditions prevail as high pressure remains in control with

clear skies and light winds.Clouds will continue to increase 

from west to east tonight into Monday morning as a trough moves 

into the region. Precipitation will likely reach the vicinity of

KSUN sometime in the late morning/early afternoon where VCSH 

and SHRA has been introduced. This VCSH and SHRA expands to

other TAF sites throughout the day with an increase in winds, 

clouds, and precipitation chances throughout eastern Idaho late

tomorrow afternoon and evening. While the latest HREF model

probability of thunder shows a 10-20% chance of thunderstorms 

Monday afternoon and evening, have kept the mention out of the 

TAFs at this time given the lower probabilities.



&&



.PIH WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



SHORT TERM...Messick

LONG TERM...Cropp

AVIATION...MacKay