textproduct: Boise

LONG TERM...Friday through Tuesday

The upper level trough responsible for the unsettled weather on Christmas will shift eastward on Friday. As the low passes, precipitation continues as moisture and dynamics taper off. Orography is expected to be the main precip inducer. Snow levels drop from 3-4 kft MSL Friday to valley floors Saturday morning. Precipitation during this time decreases, with a total rainfall/liquid equivalent of less than 0.1" in low elevations and about 0.25" in mountains. Snowfall of 1-5" in mountain towns and ridges is expected. Saturday, drying conditions spread west to east as a ridge builds, bringing northwest flow on Saturday. The ridge continues to build through Tuesday, pushing the storm track north with a cut off low off the SoCal coast. This setup will support strong subsidence, clear skies, and light winds. So with recent rains, inversions that build during this time will have favorable conditions to become long lasting with stratus/fog. This means forecast max temps may be too high during the long term. A potential return to unsettled weather seems less likely than previous model runs, especially given deterministic model consensus on the cut off low rejoining the flow in the extended.

AVIATION

Localized LIFR in fog in the lower Treasure Valley. Light precipitation is moving SE to NW this morning, but will quickly move out of the region later this afternoon leading to VFR conditions through Wed morning. Fog redevelopment is possible Wed morning. Snow levels of 7 kft MSL persist. Surface winds: SW-SE 5-15 kt. Winds aloft at 10kft MSL: SW 25-45kt.

KBOI...Light rain and drizzle this morning moving to the NW, expected to be clear of the area by Tue/16Z. VFR with high clouds through the rest of the TAF period. Surface winds SE 6-10 kt.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Wind Advisory from 8 AM to 2 PM MST Wednesday IDZ015-030. OR...None.