textproduct: Boise

LONG TERM...Wednesday through Sunday

A large ridge is expected to continue building over the area Wednesday through Thursday. A slight warming trend will bring daytime temperatures in lower elevations from the mid-to-upper 40s Wednesday to the lower 50s Thursday, while higher elevations will continue seeing peak temperatures in the mid 30s to lower 40s on both days. This ridging pattern is still expected to steer moisture off the Pacific NW coast into the area, bringing a 20-30% chance of precipitation for lower elevations and a 50-70% chance for higher elevations on Wednesday. A weak shortwave trough will dig North of the area late Thursday into early Friday, bringing a 30-40% chance of precipitation for higher terrain areas on Thursday. The slight warming trend is expected to increase snow levels back up into the 5000-7000 ft range from Wednesday to Friday, so the central mountains of SW ID and SE OR may see wintry mix in precipitation throughout the week. A large-scale trough digging across W'rn Canada and the NW region is expected to return a cooling trend and precipitation over the entire area Friday through Sunday, though considerable uncertainty over the longwave trough's arrival remains.

AVIATION

MVFR to LIFR in areas of freezing fog/low stratus developing overnight into Monday morning. Highest chances for LIFR fog/stratus in valleys/basins of E-central OR, Upper Treasure Valley, and portions of the Magic Valley, with lower chances elsewhere. Conditions improving by Sunday afternoon. Cold front with rain/snow arriving from the NW Sunday night/early Monday morning. Surface winds: variable or SE 10 kt or less, becoming SW-NW under 7 kt Sunday afternoon. Winds aloft at 10kft MSL: SW to W 10-20 kt.

KBOI...Freezing fog/mist from NW overnight through late morning around 16Z, with intermittent periods of clearing possible. 10-20% chance of precipitation Sunday night/Monday early morning. Surface winds: SE 3-7 kt early morning, becoming NW 3-7 kt late morning/early afternoon.

AIR STAGNATION

High pressure will keep stagnant air in place today. Daytime mixing heights will be 1500 to 2500 feet AGL. Relatively light winds and a low-level inversion will continue to limit ventilation in most valleys. A cold front tonight into Monday morning will remove the inversion, which will combine with breezy west to northwest winds to improve mixing and ventilation.

BOI WATCHES/WARNINGS/ADVISORIES

ID...Dense Fog Advisory until 10 AM MST this morning IDZ012-014-033. OR...Dense Fog Advisory until 10 AM MST /9 AM PST/ this morning ORZ064.