textproduct: Boise

UPDATE

Updated aviation discussion.

KEY MESSAGES

- A strong cold front moves through the region today bringing valley rain and mountain snow.

- Slight chance of thunderstorms this afternoon and evening with the potential for gusty outflow winds up to 45 mph, small hail, and brief heavy rainfall.

- Windy conditions Thursday, particularly across south central Idaho where gusts up to 50 mph are expected.

- Potential for another cold front Monday and Tuesday bringing additional gusty winds.

SHORT TERM /Through Friday Night/

A strong cold front will push into southeast Oregon and southwest Idaho today. This will bring widespread precipitation concentrated primarily just ahead of the boundary. This is a particularly dynamic system which will bring widespread precipitation along with potentially stronger embedded thunderstorms capable of producing heavy rain, small hail, and gusty winds. Instability associated with the frontal passage, with CAPE values ranging from 100 to 250 J/kg, will support a slight chance of thunderstorms (20% chance) along and just behind the front. High resolution models indicate the potential for stronger showers or isolated thunderstorms to produce outflow wind gusts up to 45 mph, especially in the Treasure Valley and Magic Valley during the early evening hours.

Valley rain and mountain snow will be the primary modes of precipitation. Snow levels will start around 5500 to 6500 feet MSL this morning, lowering to 4500 to 5500 feet MSL by this evening behind the front. Up to 0.25 inch of rain is possible in the valleys. In the mountains, rain will switch to snow above 4500 feet. However, snow accumulations will be minimal with around an inch possible in the Long Valley and 3 to 6 inches above 6000 feet.

By Thursday, the main frontal boundary will have exited to the east, but the region will remain under a cool and moist northwest flow. Showers will likely linger over the mountains. The primary concern for Thursday will be the wind. Strong post- frontal northwest winds are expected to develop, with wind gusts up to 50 mph for the Upper Treasure Valley (Mountain Home to the east), Western Magic Valley, Camas Prairie, and southern Twin Falls County. A Wind Advisory has been issued for these areas.

The back end of the deepening trough will maintain cool and breezy conditions through Friday. High temperatures will drop to a few degrees below seasonal normals. While the majority of the lower valleys will see drying conditions, moist north-northwest flow will keep a 20 to 40 percent chance of light snow or rain showers over the higher terrain, particularly in the west- central Idaho mountains. Wind gusts of 25 to 35 mph remain possible in the wind-prone areas of south-central Idaho through Friday afternoon before diminishing Friday night as high pressure begins to build in from the west.

LONG TERM /Saturday through Wednesday/

This coming weekend be generally dry as a building ridge over the North Pacific extends an eastern wing across our area. This ridging will allow for a warming trend, with temperatures near normal Saturday warming to 5-10 degrees above normal come Sunday. Saturday will feature increased high clouds as a shot of moisture works it's way around the ridge, before clearing Sunday.

Come Monday/Tuesday, the brief ridging over our area will break down as a cold front moves its way across our area from the northwest. Moisture continues to look limited, with a trajectory over the North Cascades. However, precipitation chances will increase (to 30-70%) over our northern mountains zones thanks to some orographic lift. Snow levels will drop to be at or near valley floors following this cold front, beginning at 6.5-7.5kft MSL Monday morning, lowering to 1-2.5kft come Tuesday morning. However, as mentioned above, moisture will be limited so accumulations are only anticipated over the central Idaho Mountains. Gusty winds will accompany this cold front, especially Tuesday afternoon where there is a 70-80% chance of wind gusts of 30+ mph in Mountain Home and eastward through the Snake River Plain. In the Camas Prairie, there is a 75% chance of wind gusts of 35+ mph. With the support of strong (30-50 kt) 700mb winds oriented roughly with the Snake River Plain, have adjusted the forecasted winds/wind gusts towards the NBM 75th/90th percentiles. Unsettled northwesterly flow aloft will allow for showers to persist over the central Idaho Mountains through Wednesday. Cooler and unsettled conditions appear likely beyond Wednesday, with the Pacific North American Oscillation remaining in a negative phase.

AVIATION /12Z Wednesday through Thursday/

Issued 435 AM MST WED MAR 4 2026

A cold front will bring widespread rain and mtn snow from NW- SE, entering E-Oregon Wed/AM. Precip becoming scattered by Wed/PM following the frontal passage. A 15-20% chance of lightning Wed/PM. Low VFR to IFR conditions in rain, IFR-LIFR in snow. Mountains obscured. Snow levels: 6.5-7.5 kft MSL lowering to 3.5-4.5 kft MSL by Thu/06z. Surface winds: S-E 5-15 kt this morning, becoming W-NW 10-25 kt with gusts to 35-45 kt behind the front. Winds aloft at 10kft MSL: W-SW 15-30 kt.

KBOI...VFR this morning. A cold front bringing persistent rain to arrive Wed/20-21z. precip becoming showery after Thu/01z. Conditions degrading to MVFR as precip begins with IFR conditions in heavier rain. A 15-20% chance of lightning Wed/PM. Foothills obscured in precip. Surface winds: SE increasing to 10-15 kt with occasional gusts to 20 kt this morning. Becoming W-NW 10-20 kt with gusts to 20-30 kt behind the front.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Wind Advisory from 11 AM to 8 PM MST Thursday IDZ014-016-028-030. OR...None.