textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Widespread valley rain and mountain snow above 4500 feet on Monday.

- Much cooler temperatures with rain and snow showers Wednesday through Friday.

- Snow levels will drop to near valley floors Thursday morning, with widespread lower elevation light snow likely.

SHORT TERM /Through Wednesday Night/

Wraparound moisture is filling in across the region, with rain below about 5500 feet. Nearly 1 inch of rain fell on Sunday across the region, with many locations overachieving significantly on precipitation amounts. As air continues to cool overnight, snow levels will drop to 4500 feet by the early morning, with about 1-3 inches of snow expected near McCall, ID and Idaho City, ID. This snow will likely melt quickly, as highs across the mountain valleys increase to the mid 40s by late morning. Valley rain and mountain snow will continue generally north of Mountain Home, ID overnight into mid morning, with breezy southwesterly winds accompanying the precipitation. The wraparound moisture and low center will move east by Monday afternoon, with precipitation generally tapering off by early afternoon. Graupel showers and a stray thunderstorm will form over over southeast Oregon by early afternoon, moving into southwest Idaho and lessening in coverage by early evening. Clearing Monday night into Tuesday morning will allow for fog formation across area valleys, especially in higher terrain.

Dry conditions will continue on Tuesday as cool northwesterly flow aloft moves in. A very cold low pressure system will then move into the Pacific Northwest on Wednesday, bringing a robust cold front to the region on Wednesday evening. Gusty winds, isolated thunderstorms, and another push of widespread precipitation will accompany this frontal passage. Temperatures will drop to below freezing by Wednesday night, with most higher elevation locations changing from rain to snow by early evening.

LONG TERM /Thursday through Monday/

A cold front will continue to exit our area through Friday, ushering in a colder air mass and gusty west/northwest winds. While widespread precipitation will taper off, colder air aloft will allow for scattered showers to develop across the area. Depending on the exact low track, the West Central Mountains could see persistent additional precipitation on Thursday with the deformation zone of the low overhead. Snow levels will drop to valley floors on Thursday behind this front. Low snow levels, combined with diurnal instability, will support snow/wintry mix and graupel showers area- wide. Additional snowfall amounts of up to 4 inches are expected above 4500 ft MSL Thursday. Southern portions of the western Magic Valley have a 40-50% chance of seeing at least a half inch of snowfall. Elsewhere, little to no accumulations are expected. Winds Thursday afternoon will gust to 25-45 mph, with the strongest gusts in the typical areas east of Mountain Home and in the Camas Prairie. Temperatures Thursday morning will be near freezing throughout the Snake Plain, with widespread temperatures at or below freezing come Friday morning. For those who started their garden early, it may be good to consider covering up plants or bringing them inside.

Precipitation chances and winds will taper off Friday, as the system exits our area to the east. This will also mark the start of a warming trend, with temperatures back up to near normal by Saturday as a ridge begins to build in. By Sunday, temperatures will warm to 5-10 degrees above normal. Confidence is increasing on another system digging down from the Gulf of Alaska early next week. While exact timing is uncertain, this will lead to increasing precipitation chances Sunday afternoon, remaining elevated (30-60%) through Monday.

AVIATION /06Z Monday through Tuesday/

Issued 606 AM MDT MON APR 13 2026

Widespread showers resulting in low VFR/IFR in rain and IFR/LIFR in snow. Mtns obscured. Showers becoming scattered Mon/PM, tapering off by early Tue/AM. Isolated thunderstorms after Mon/18z. Snow Levels: 4500-5000 ft this morning, rising to 5500-6000 ft Mon/PM. Surface winds: W-NW 5-15 kt with gusts to 20-25 kt, becoming variable up to 10 kt overnight. Winds aloft at 10kft MSL: NW-SW 15-30kt.

KBOI...Rain continuing through the morning, showers becoming scattered. Showers becoming scattered late Mon afternoon. Slight chance of fog/low stratus Mon night/Tue AM. Surface winds: variable or SE 5-10 kt, transitioning to SW-NW 5-15 kt mid Monday morning.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.