A powerful cold front will sweep through eastern Oregon early this evening and southwest Idaho around 8 pm this evening, bringing wind gusts up to 50 mph, isolated thunderstorms, and widespread precipitation that will transition to heavy mountain snow by Wednesday.
Heavy rain/storms/wind & heavy mountain snow return to Idaho
The cold front moves through eastern Oregon this afternoon and crosses into southwest Idaho this evening. Showers and thunderstorms will form in the late afternoon and sweep eastward across the area. Along the front, wind gusts could reach 50 mph. Tonight's forecast includes a 90 percent chance of showers and thunderstorms, with low temperatures around 43 degrees.
As the system moves directly overhead on Wednesday, conditions will become much cooler with widespread precipitation. Valley locations can expect 0.25 to 1.0 inch of rainfall, while the mountains will see 1 to 2 inches of liquid equivalent. Snow levels will drop to between 4,000 and 5,500 feet behind the front. Peaks above 6,000 feet, especially those facing northwest, will receive 10 to 20 inches of new snow.
Precipitation will taper off across southeast Oregon late Wednesday afternoon but will continue over the central Idaho mountains into Thursday morning. By Thursday afternoon, conditions will dry out, leaving cool and breezy weather with a high near 55 degrees. A shortwave trough will bring another push of precipitation over higher terrain late Friday into Saturday.
Temperatures will remain slightly below normal through the weekend. A ridge of high pressure over the eastern Pacific will maintain a cool northwesterly flow through early next week. While there is some model disagreement, precipitation chances of 20 to 40 percent will linger over high terrain near the Nevada border and the West Central and Boise Mountains Sunday through Tuesday. A slight warming trend will begin late Tuesday as the high-pressure ridge moves onshore, pushing high temperatures to near 68 degrees.
Tonight
Showers and thunderstorms likely before 1am, then showers and possibly a thunderstorm between 1am and 3am, then showers after 3am. Low around 43. West northwest wind 11 to 16 mph becoming east 5 to 10 mph in the evening. Winds could gust as high as 33 mph. Chance of precipitation is 90%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.
Wednesday
Showers. High near 52. South wind 7 to 15 mph becoming west northwest in the afternoon. Winds could gust as high as 28 mph. Chance of precipitation is 90%. New precipitation amounts between a half and three quarters of an inch possible.
Wednesday Night
Showers, mainly before midnight. Low around 41. West northwest wind 7 to 13 mph, with gusts as high as 24 mph. Chance of precipitation is 80%. New precipitation amounts between a tenth and quarter of an inch possible.
Thursday
A 20 percent chance of showers after noon. Partly sunny, with a high near 55. West northwest wind 7 to 14 mph, with gusts as high as 24 mph.
Thursday Night
Mostly clear, with a low around 34. North northwest wind 5 to 14 mph, with gusts as high as 25 mph.
Friday
Mostly sunny, with a high near 58.
Friday Night
Partly cloudy, with a low around 34.
Saturday
Mostly sunny, with a high near 60.
Saturday Night
Mostly clear, with a low around 37.
Sunday
Mostly sunny, with a high near 61.
Sunday Night
Partly cloudy, with a low around 39.
Monday
Mostly sunny, with a high near 63.
Monday Night
Partly cloudy, with a low around 40.
Tuesday
Sunny, with a high near 68.
