textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- Much cooler today with widespread showers, isolated thunderstorms, gusty winds, and snow levels 4500 to 5500 feet.

- Precipitation totals of 1 to 2 inch in the mountains, 0.25 to 1.0 inch in the valleys.

- Snow accumulations of 10 to 20 inches on the peaks above 6000 feet, highest on the northwest facing peaks.

- Remaining cool and unsettled through the weekend and into early next week.

SHORT TERM /Through Friday Night/

Issued 333 AM MDT WED APR 22 2026 The center of an upper low will move overhead this morning, bringing widespread rain and mountain snow. After steady precipitation this morning, it will become more showery this afternoon as the low center departs. A slight chance of thunderstorms will also develop, mainly on the Idaho side. The mountains will continue to see heavier amounts this afternoon as orographic lift is enhanced under moderate westerly flow aloft. Snow levels will be 4500-5500 feet, limiting significant snow amounts to higher peaks. Temperatures today will be 20-30 degrees cooler than yesterday, with highs around 10 degrees below normal. The departing low will bring gusty winds to the area, especially across southeast Oregon and far southern Idaho where frequent gusts of 25-40 mph are expected. A few gusts to 45-50 mph are also possible in these areas.

A trailing shortwave trough will move through tonight, bringing additional showers. Precipitation chances will decrease from west to east overnight as the trough exits the area. Precipitation totals today through tonight will be significant, with most lower elevations picking up 0.25-1.0 inch of rain, with higher totals more likely near the foothills. In the Treasure Valley, there is a 10-30% chance of 1 inch of rain or more, with a 40% chance near the foothills. Precipitation totals of 1-2 inches will be common over the mountains, with locally higher amounts on windward slopes. Above 6000 feet, this will be in the form of heavy snow with 10-20 inches expected. From 4500-5500 feet, generally less than 1 inch of snow is anticipated.

Northwest flow will persist across the area Thursday and Friday with a couple of shortwave troughs brushing our northern area. This will keep temperatures 5-10 degrees below normal with gusty afternoon winds, strongest Thursday across southern Idaho where gusts 30-45 mph will occur. The troughs will keep a 40-80% chance of snow across the central Idaho mountains, with less than a 20% chance of precipitation elsewhere. Snow amounts will be light. Weak instability will support a 10-20% chance of thunderstorms Thursday afternoon across the mountains. Additionally, low temperatures at agricultural locations in the lower valleys will dip into the low to mid 30s Thursday and Friday nights, resulting in a risk of frost/freeze.

LONG TERM /Saturday through Wednesday/

Issued 333 AM MDT WED APR 22 2026 Cool and unsettled conditions are expected through the weekend and into early next week as troughing persists over the PacNW. Temperatures will remain a few degrees below normal through Monday. The airmass will gradually modify and warm for Tuesday and Wednesday as the trough weakens and becomes disorganized. Though moisture will be limited, the unstable cool air aloft will help to generate showers over the higher terrain each day, with lower chances for the valleys. Snow levels will range from 4500-6500ft MSL, with the lower levels for the north and higher levels across the south. Models hint at weak ridging developing mid to late next week, which would support warming and drying across the forecast area.

AVIATION /12Z Wednesday through Thursday/

Issued 613 AM MDT WED APR 22 2026

Numerous showers through tonight. Isolated afternoon thunderstorms in SW Idaho. Low VFR-IFR in rain, IFR-LIFR in mtn snow. Mtns obscured. Snow Levels: 4500-6000ft MSL. Surface winds: SW-NW 10-25 kt with gusts to 20-35 kt. Winds aloft at 10kft MSL: W-NW 20-40 kt.

KBOI...Rain showers continuing today, with periods of MVFR conditions throughout the morning hours. Showers ending around Thu/07Z. Surface winds: light and variable, becoming W-N 8-18 kt by late morning. Gusts to 25-30 kt returning late morning through early evening.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None.

OR...None.