textproduct: Boise

DISCUSSION

A few leftover showers this evening across the w-central ID mtns will add little if any additional accumulation. The chance for measurable snow will be less than 30% north of a line from Halfway to Warm Lake. Otherwise looking a dry conditions with periods of clouds as a ridge of high pressure builds in aloft. Evidence of the ridge can be seen on the evening KBOI sounding which shows a subsidence inversion just under 500mb (~15kft MSL). Given the dry air in place expect fog to be limited to mtn valleys or along the foothills in some locations overnight. Current forecast is on track so no updates for this evening.

AVIATION

Mainly VFR with isolated MVFR-IFR snow showers lingering over the higher terrain of Eastern Oregon and Central ID. Patchy fog and low stratus is possible in sheltered valleys Friday morning. Isolated shower chances end by Friday afternoon into evening. Sporadic mountain obscuration in precipitation and low clouds. Surface winds: W-NW 10-20 kt becoming light and variable overnight, except the Western Magic Valley maintaining W-SW 10-20 kt. Winds aloft at 10kft MSL: N-NW 20-35 kt.

KBOI...VFR with lower clouds/fog near the foothills developing overnight into early morning. Surface winds: W-NW 5-9 kt becoming SE 3-7 kt after Fri/10z.

Weekend Outlook...Mostly VFR with clear skies on Saturday and increasing clouds on Sunday. Localized LIFR-IFR conditions in patchy morning fog in sheltered valleys on Saturday. Generally variable surface winds less than 10 kt.

PREV DISCUSSION

SHORT TERM...Tonight through Saturday night...Cool and unstable northwest flow continues through Friday. Breezy west to northwest winds this afternoon will slowly subside overnight. Enough instability remains for snow showers over the mountains this afternoon and again on Friday, with flurries possible in the valleys through this evening. Conditions dry out on Friday as a ridge builds across the Western US. Temperatures will be near normal today, moderating a few degrees each day as the ridge develops.

LONG TERM...Sunday through Thursday...Little update from previous forecasts, a ridge continues to build over the region through the long term. Conditions will be dry with a near zero percent chance for precipitation. The high pressure will support inversion development, keeping air stagnant and making fog and stratus likely each morning. Monday through Tuesday, the storm track north of the area just clips are area enough to bring a 10% chance of precipitation from showers to the far northern reaches of our CWA. The high pressure amplifies to a closed high on Wednesday, then shifts from northern California to the Pacific Northwest coast. This evolution of the high will not only push exacerbate dry and inverted conditions, but will also set up an omega block pattern heading into late next week.

BOI WATCHES/WARNINGS/ADVISORIES

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