textproduct: Boise

LONG TERM...Sunday through Thursday

The extended period will see no significant changes to the prevailing pattern, as a persistent southwesterly flow remains established ahead of a deep upper-level trough off the West Coast. This setup will direct a continuous plume of subtropical moisture toward southeast Oregon and southwest Idaho throughout the week. The initial arrival of moisture is expected between Sunday morning and Sunday night as a warm front lifts northward, bringing widespread precipitation to the region. Snow levels will initially range from 3,0005,000 feet MSL in the north to 6,0007,000 feet MSL in the south, rising steadily across all areas through the day.

Precipitation will persist into Monday, supported by a strong southwesterly flow aloft that will keep snow levels elevated. While there is high confidence in moderate to heavy liquid precipitation totals, significant snowfall will be restricted to the higher elevations. Forecast models indicate over an inch of liquid equivalent across the Central Mountains, while the Snake River Plain will likely see about half that amount due to pronounced rain- shadowing. The highest peaks could receive up to a foot of snow, but accumulations in lower mountain valleys will likely be limited to a few inches.

From Tuesday into Wednesday, the flow aloft is forecast to become more southerly as the offshore trough deepens. This transition will further drive up temperatures and snow levels. Precipitation chances will hold at 2550% on Tuesday, primarily for rain and high- elevation snow, before increasing to 3575% on Wednesday. Guidance suggests this pattern will hold through Thursday as the trough edges closer to the Pacific Coast. While this may eventually bring slight cooling and lower snow levels, the region is expected to remain on the warm side of the system, ensuring continued periods of precipitation with medium-to-high snow levels.

AVIATION

Snow or wintry mix continuing across parts of southeast Oregon and much of southwest Idaho this afternoon. Snow is expected to transition to rain below 5k-8k feet by early evening. Remaining snow/mix for W-Cntrl ID/Boise mountain- valleys until late evening. VFR-MVFR in rain, MVFR-LIFR in snow. Mountains obscured. Surface winds: variable up to 12 kt. Then SW-SE 10-25 kt with gusts of 25-45 kt Thu PM, strongest west/south of Snake Plain. Locally higher gusts on mtn tops. Winds aloft at 10kft MSL: W 20-30 kt, then W-SW 40-75 kt by Thu/18Z.

KBOI...MVFR in rain showers through 00z. Broken to overcast mid clouds overnight. Surface winds: SE 12-18 kt with gusts 25-35 kt through Friday morning.

Weekend Outlook...Cold front Friday with precip moving from N to S. Mtns obscured. Snow levels 3k-5k ft MSL for north, 5k-7kft for south, lowering by Fri night. IFR/LIFR in snow, VFR/MFR in rain. Showers tapering off Sat, lingering mtn obscuration and patchy AM fog. Widespread rain/snow Sunday. Snow levels 3k-5kft MSL to north, 6k-7kft to south, rising throughout day. Mtns obscured. Surface winds Fri: SW-SE 15-30 kt, gusts 25-45 kt, except 50-55 kt on mtn tops. Sat: SW-SE 5-15 kt. Sun: SW-SE 10-20 kt, gusts 20-35 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Wind Advisory from 8 PM this evening to 5 PM MST Friday IDZ015-029-030. OR...Wind Advisory from 8 PM MST /7 PM PST/ this evening to 5 PM MST /4 PM PST/ Friday ORZ061-063.