After a remarkably wet start to the month, a strong cold front will sweep through the region late Wednesday, bringing snow to valley floors and freezing temperatures that threaten early spring plant growth.
A remarkably wet April so far
An active weather pattern brought widespread rain and mountain snow to the area on Monday. Significant snow fell above 6,000 feet, with reports of 14 to 18 inches of accumulation. Meanwhile, Boise has recorded 2.40 inches of rainfall so far this month. With 17 days still remaining, this already ranks as the 9th wettest April on record for the Boise area.
Brief break Tuesday before the next storm
The widespread precipitation will taper off Monday evening, providing a short lull in the active weather. Light winds, clearing skies, and significant surface moisture will promote the development of patchy fog Tuesday morning, especially across Long Valley and the Treasure Valley.
The break in the weather will be short-lived. A strong low-pressure system currently over Alaska will begin moving south along the Pacific coast late Tuesday. Clouds will increase from the west, and light rain showers will develop over the mountains of southeast Oregon late Tuesday before spreading into southwest Idaho overnight.
Valley snow arrives Thursday
The main weather event arrives Wednesday ahead of a cold front. Strong southwesterly winds will create breezy conditions Wednesday afternoon, with gusts of 25 to 35 mph possible across the higher terrain and open valleys of southeast Oregon. Widespread rain is expected for the valleys through Wednesday evening, with snow levels initially remaining around 5,000 to 6,000 feet.
The cold front will pass through the region late Wednesday night into early Thursday morning, bringing a sharp transition in the weather. Winds will shift to the northwest and remain gusty as a much colder air mass pours into the region.
Snow levels will plummet toward valley floors by sunrise Thursday. A mix of rain and snow is expected for the Treasure and Magic Valleys, with light snow accumulations possible on grassy surfaces and higher valley benches. In the mountains, lower valleys will see a few inches of snow, while areas above 5,500 feet could see several inches of new snow Thursday morning, which may impact travel over mountain passes.
Protect your spring plants and gardens
Following the cold front, temperatures on Thursday will drop 5 to 10 degrees below normal. This sudden burst of winter will bring sub-freezing morning low temperatures to most of the Snake Plain Thursday through Saturday.
Because the recent warm spell caused many plants to bloom or sprout, these freezing morning temperatures threaten new growth, especially for gardens and crops. Anyone who started their garden early should consider covering plants or bringing them inside.
As the snow tapers off Thursday evening, high pressure will build and initiate a warming and drying trend. While morning lows will stay near freezing through Saturday, afternoon high temperatures will climb back to near normal. By Sunday, temperatures will reach about 5 degrees above normal before another strong storm system arrives Sunday night.
Tonight
A 20 percent chance of showers before midnight. Patchy fog after midnight. Otherwise, partly cloudy, with a low around 38. Light wind.
Tuesday
Patchy fog before 9am. Otherwise, mostly sunny, with a high near 60. Light wind.
Tuesday Night
A 40 percent chance of showers after midnight. Increasing clouds, with a low around 44. Calm wind.
Wednesday
Showers, with thunderstorms also possible after 3pm. High near 57.Locally breezy in the afternoon. Chance of precipitation is 100%. New rainfall amounts between a quarter and half of an inch possible.
Wednesday Night
Rain showers before 3am, then a chance of snow showers. Some thunder is also possible. Low around 33. Chance of precipitation is 90%. Little or no snow accumulation expected.
Thursday
Snow showers likely before 3pm, then rain and snow showers likely. Some thunder is also possible. Partly sunny, with a high near 46. Chance of precipitation is 60%. Little or no snow accumulation expected.
Thursday Night
Partly cloudy with a frost or freeze likely, with a low around 28.
Friday
Sunny with a cold morning, with a high near 55.
Friday Night
Mostly clear, with a low around 32.
Saturday
Mostly sunny & milder, with a high near 63.
Saturday Night
Mostly cloudy, with a low around 42.
Sunday
A 20 percent chance of showers. Partly sunny & milder, with a high near 68.
Sunday Night
A 30 percent chance of showers. Mostly cloudy, with a low around 42.
Monday
A chance of showers. Partly sunny, with a high near 63.
