textproduct: Boise

LONG TERM...Friday through Tuesday

Moisture will persist over the forecast area on Friday ahead of, and along a cold front expected by Friday evening. The strong mid-level jet in place will support upslope precipitation across west-central and central Idaho terrain, and will aid in valley shadowing effects. Snow levels will still be on the higher side ahead of the front, around 5000 feet MSL for the north and 7500 feet for the south. A sharp gradient in snow levels will develop with the arrival of the cold front, with 2500 feet for the north and 6500 feet for the south by early Saturday. The lower snow levels will result in moderate to heavy snow accumulations for those higher elevations of central ID Friday into Saturday, with liquid equivalent potentially exceeding an additional 1". This period of precip over saturated, steep terrain will also introduce rockslide concerns below the snow line. In addition to precip, strong surface winds are anticipated across much of the area Friday ahead of/along the cold front. Gusts will be strongest across southeast Oregon and the mountains of southwest Idaho. Meanwhile, temperatures are forecast to stay above normal Friday, with the coldest air expected across west- central/central Idaho and northeast Oregon. Temperatures should lower by several degrees Saturday for all areas behind the cold front, but above normal temperatures will still persist for most.

As the aforementioned system exits, another windy and very wet elongated trough will impact the area beginning early Sunday. The accompanying plume of subtropical moisture will help to amplify a ridge over the west as it brings in warmer air. Cool, but above normal, temperatures on Sunday will jump up to 10-20 degrees above normal on Monday. Snow levels will be 3500 feet to the north and 7000 feet to the south, then quickly rise to 6000-8000 feet by early Monday. Though precip chances are forecast area-wide, the west- central/central Idaho terrain will be favored once again. Periods of precip will continue Tuesday, with the coldest air remaining to the northwest of the area.

AVIATION

Patchy fog/mist around KONO to KMAN through AM. Some mtn obscuration from low clouds. Otherwise, VFR through afternoon. Rain arriving from SW after sunset. Snow for elevations above 7-8 kft MSL. Low VFR/MVFR in heavier rain, IFR/LIFR in snow. LLWS threat becoming area-wide late tonight. Surface winds: SW-SE 5-15 kt, afternoon gusts to 20-30 kt for SE Oregon and near ID/NV border. Gradually increasing tonight/early Wed to SW-S 15-30 kt with to 30- 50 kt gusts, locally higher on mtn tops.

KBOI...Mainly VFR. A 60% chance of rain beginning around Wed/02Z-03Z, increasing to 90% chance overnight. Brief MVFR possible at precip onset prior to increasing wind speeds. Low level wind shear threat ramping up overnight. Surface winds: becoming SE 5-15 kt by mid morning. Increasing to SE 15-20 kt overnight, with 25-30 kt gusts. Then W-NW 15-25 kt with 35-45 kt gusts beginning approx Wed/15Z with cold front.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Wind Advisory from 5 AM to 5 PM MST Wednesday IDZ011-013>016-029-030. High Wind Warning from 8 AM to 5 PM MST Wednesday IDZ028. OR...Wind Advisory from 5 AM MST /4 AM PST/ to 11 AM MST /10 AM PST/ Wednesday ORZ061>063.