A significant rain event will impact the region tonight through Wednesday morning, bringing heavy precipitation to the Boise and west-central Idaho mountains with an elevated risk of rock and mud slides along steep terrain.
The latest weather models have slightly lowered total rainfall amounts for most areas tonight through Wednesday morning, though the Boise Mountains and west-central Idaho mountains actually saw a slight increase, now forecast to receive 1.00 to 2.25 inches of rain. The greater rainfall amounts in these areas increase the danger of rock and mud slides down steep terrain. People would be wise to avoid roads like the Banks-Lowman Road and other routes below steep terrain in Idaho until rain ends Wednesday evening.
Most recent models are also showing higher snow levels than previously forecast, which has led to a reduction in total snowfall below 7,000 feet through Wednesday morning. Additionally, the latest models are showing windier conditions Wednesday, with gusts in south-central Idaho approaching Wind Advisory criteria Wednesday afternoon. A formal advisory has not been issued with this forecast package, but if the next model cycle continues the trend, one will be issued at that time.
Rain will end Wednesday morning with skies gradually clearing through the afternoon. A dry northwest flow will then settle in through Friday as the storm track positions itself along the United States-Canada border, bringing a welcome break from the recent active pattern.
The next weather system approaches over the weekend as a closed low moves toward the California coast. This wind shift will inject moisture into the region Saturday and Sunday, though the lack of strong dynamic energy or atmospheric flow aloft limits precipitation potential. A general 20 to 40% chance of precipitation is expected Saturday and Sunday, trending toward drier conditions Monday. Temperatures will run at or slightly above normal through the weekend.
Mountain Snow Conditions for Ski Areas
The elevated snow levels through Wednesday morning mean most precipitation will fall as rain rather than snow at ski area base elevations. However, the highest peaks above 7,000 feet will still receive some snowfall. The drier conditions Thursday through Friday will provide a brief respite before the next system brings additional moisture over the weekend.
Tonight
Rain after 11pm. Low around 42. East southeast wind 3 to 6 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Tuesday
Rain. High near 50. East southeast wind 5 to 7 mph. Chance of precipitation is 100%. New precipitation amounts between a half and three quarters of an inch possible.
Tuesday Night
Rain likely, mainly before 11pm. Cloudy, with a low around 41. Southeast wind around 5 mph becoming light and variable in the evening. Chance of precipitation is 60%.
Wednesday
Mostly cloudy, then gradually becoming sunny, with a high near 52. NW wind 5-15 mph, with gusts as high as 25 mph.
Wednesday Night
Mostly clear, with a low around 30. Northwest wind 5 to 10 mph becoming light and variable in the evening. Winds could gust as high as 20 mph.
Thursday
Mostly sunny, with a high near 53.
Thursday Night
Partly cloudy, with a low around 34.
Friday
Mostly sunny & unseasonably mild, with a high near 57.
Friday Night
Partly cloudy, with a low around 36.
Saturday
A 30 percent chance of rain, mainly after 11am. Partly sunny, with a high near 56.
Saturday Night
A 30 percent chance of rain. Mostly cloudy, with a low around 37.
Sunday
Partly sunny & mild, with a high near 55.
Sunday Night
Mostly clear, with a low around 33.
Monday
Mostly sunny & continued mild, with a high near 56.
