textproduct: Boise

DISCUSSION

Dry, mostly clear, and cold conditions will return for the region tonight. Above normal temperatures will continue through Sunday thanks to a building ridge of high pressure. Early morning low temperatures tonight will be slightly warmer than this morning, especially in mountain valleys. A low pressure system is still on track to bring precipitation and cooler temperatures tomorrow evening into Sunday. Afternoon thunderstorms are possible (<20% chance) near the Nevada border. No updates needed to the forecast.

AVIATION

VFR. Showers arriving in SE Oregon/SW Idaho from Nevada Saturday afternoon, creating local MVFR ceilings and mountain obscuration. Snow levels: 7000-8500 ft MSL during shower activity. A 15% chance of afternoon lightning in S Harney County. Surface winds: variable 5-15 kt. Winds aloft at 10kft MSL: westerly 10-30 kt.

KBOI...VFR. SE up to 8 kt, then light and variable Saturday afternoon.

Sunday Outlook...Showers expanding northward Sunday. A 15% chance of lightning near NV border. MVFR-IFR developing in mtn snow and heavier rain showers. Mtns obscured. Snow levels: 6-8kft MSL, lower for north. Surface winds: SW-SE 5-15 kt, gusts up to 30 kt with storms.

PREV DISCUSSION

SHORT TERM...Tonight through Sunday night...High clouds will continue to hug the NV border overnight, with mostly clear skies to the north. An upper low approaching the northern CA coast will push clouds further north on Saturday. Light precipitation will break out along a warm front late Saturday into Sunday. The front will weaken as it lifts north resulting in liquid totals less than 0.10 inches for most spots from the Snake Plain into the Boise and west-central Idaho Mountains. Areas to the south and west will see higher amounts with a range of 0.1-0.3 inches through Sunday night. Snow levels will rise to between 6-8kft MSL by Sunday afternoon. Snow accumulation will be less than an inch at all but the highest elevations in the Steens. Southern areas along the NV border will see an uptick in the chance of thunderstorms Sat/Sun afternoon. For now the NBM keeps the threat at less than 15%, though some high resolution models are showing signs of t-storm development across SE Oregon Sat/Sat night, spreading eastward along the ID/NV border on Sunday. Temperatures will remain 5-10 degrees above normal through the weekend.

LONG TERM...Monday through Friday...Precipitation chances from the upper-level trough will linger into Monday as the system moves further east into the Great Basin. Snow levels will remain high with values ranging from 6000-7500 feet MSL. Brief upper- level ridging builds in Tuesday before another upper-level trough moves across the Pacific NW. Temperatures Tuesday will be the warmest of the period, with low 60s across parts the Snake Basin. Ensembles bring a potent cold front through the area on Wednesday afternoon, with snow levels falling to 3500-4500 feet MSL by Thursday. Snow showers continue over the higher terrain Thursday with the cold unstable air aloft. Conditions dry out on Friday between systems. A return to cool and unsettled by the following weekend.

BOI WATCHES/WARNINGS/ADVISORIES

ID...None. OR...None.