Cool, breezy, and unsettled weather will persist through Friday, bringing additional mountain snow and the threat of a frost or light freeze to agricultural valleys by the end of the week.
Chief Meteorologist Scott Dorval's video forecast highlights more chilly mornings
Record-breaking rain gives way to mountain snow
The broad, closed low-pressure system over the Pacific Northwest will lift northeast overnight, cutting off the steady precipitation that recently helped break Boise's April rainfall record. Boise has received a record .83" of rain on Wednesday and .84" of rain from this storm, bringing the monthly total to 3.83", which is the wettest on record for this far into the month.
While this low exits the region, energy dropping out of Canada will maintain a 40 to 70 percent chance of showers across the mountains in Baker County and west-central Idaho through Friday. Snow levels will drop to around 4,000 feet tonight, allowing for up to an inch of accumulation in mountain valleys. Higher elevations will see an additional 3 to 8 inches of snow, with most of it falling by midday Thursday.
Southeast Oregon and the Snake River Plain in southwest Idaho will trend drier on Thursday and Friday as shower development remains to the north and east.
Gusty winds and freeze potential
Thursday and Friday will stay breezy, aided by northwest flow on the backside of the upper trough. Each afternoon will bring wind gusts of 20 to 30 mph, with windier spots along the Interstate 84 corridor and through the Camas Prairie seeing gusts of 30 to 45 mph.
Friday and Saturday mornings will bring the chance of a frost or light freeze in the Snake River Plain. Lows will generally range between 32 and 36 degrees on Friday morning, shifting colder to between 30 and 35 degrees for Saturday morning. Agricultural interests should monitor these temperatures closely.
Unsettled weekend before a warming trend
A trough will extend into the region from a low center in central Canada through early next week. This will bring slightly below-normal temperatures and a 20 to 40 percent chance of precipitation to higher terrain through at least Monday.
A push of moisture from an embedded shortwave to the south will bring elevated precipitation chances (40 to 60 percent) to the Nevada border through early next week, though accumulation looks to be minimal. Snow levels will stay around 5,000 to 6,000 feet through Tuesday, with higher elevations seeing light snow showers this weekend through Monday.
A high-pressure system will move into British Columbia by Tuesday, starting a steady warming trend through the region and bringing temperatures back to normal for this time of year. Disagreement on the evolution of a coastal low-pressure system to the south muddles the precipitation forecast for Tuesday and Wednesday, but current chances range from 10 to 30 percent over higher terrain and near the Nevada border.
Tonight
Showers, mainly before midnight. Low around 40. WNW wind 6 to 10 mph, with gusts as high as 25 mph. Chance of precipitation is 90%. New precipitation amounts between a tenth and quarter of an inch possible.
Thursday
Mostly sunny to partly cloudy, with a high near 59. NW wind 5 to 10 mph, with gusts as high as 25 mph.
Thursday Night
Mostly clear & cold, with a low around 36. NW wind 5 to 10 mph becoming light and variable after midnight. Winds could gust as high as 23 mph in the evening.
Friday
Sunny, with a high near 58. Wind NW 5 to 10 mph in the morning. Winds could gust as high as 21 mph.
Friday Night
Mostly clear & cold, with a low around 34.
Saturday
Mostly sunny, with a high near 61.
Saturday Night
Partly cloudy & cold, with a low around 38.
Sunday
A 20 percent chance of showers after noon. Mostly sunny, with a high near 61.
Sunday Night
Partly cloudy, with a low around 38.
Monday
Mostly sunny, with a high near 63.
Monday Night
Mostly clear, with a low around 40.
Tuesday
Mostly sunny, with a high near 67.
Tuesday Night
Partly cloudy, with a low around 42.
Wednesday
Mostly sunny, with a high near 70.
