A cold front moving through Friday will bring cooler temperatures and the potential for the season's first snowflakes in valley locations, including the Treasure Valley and Magic Valley, as winter weather patterns begin to establish across Idaho.
Today Through Friday: Cold Front Arrival
An upper-level trough will move through all day Friday, bringing a cold front Friday morning. Fog may reform in sheltered valleys Friday morning as surfaces remain fairly saturated, though pre-frontal winds and partly cloudy skies lower confidence in fog development.
As the front passes Friday morning, precipitation chances rise to 40 to 60% in high elevations and 10 to 20% in lower elevations. Precipitation will remain generally north of Mountain Home, but snow levels will drop from 5,000 to 6,000 feet to 3,000 to 4,000 feet Friday night.
Rainfall amounts up to 0.1 inches are expected in mountain valleys and up to 0.2 inches on summits. Snowfall of less than 1 inch is expected below 5,500 feet, with 2 to 3 inches possible above that elevation.
Mountain Snow Conditions for Ski Areas
The approaching cold front will bring beneficial snow to Idaho's ski areas, with 2 to 3 inches of new snow expected above 5,500 feet. Snow levels dropping to 3,000 to 4,000 feet on Friday night will help build the early-season base at higher elevation resorts. Mountain passes may see light accumulations, with less than 1 inch expected at elevations below 5,500 feet. Skiers and snowboarders should monitor conditions with more substantial snowfall likely as winter patterns strengthen in December.
Weekend: First Valley Snow Possible
Friday afternoon and evening will see wind gusts pick up in the upper Snake Plain, including the Magic Valley, with speeds up to 35 mph in open areas and ridges. Friday will be about 5 degrees colder than Thursday, and Saturday will be 5 degrees colder than Friday, ending up about normal for this time of year.
Confidence has increased for a system moving in Saturday night with low precipitation amounts up to 0.05 inches. However, the timing of this system overnight with colder air in place means this could be the first sight of flurries for many low areas, including the Treasure Valley and Magic Valley. Most of the area has a 20 to 30% chance of precipitation Saturday night.
Extended Outlook: December Pattern Emerges
Drier conditions with gusty northwesterly winds will move into the area behind the exiting shortwave trough Sunday afternoon. Dry weather will continue Monday with winds slackening.
A new upper-level shortwave trough will move through the area Tuesday, spreading another round of precipitation across southwestern Idaho and southeastern Oregon. Snow levels Tuesday are expected to be around 3,000 feet, supporting a mix of rain and snow in valley locations and light snow accumulations above about 3,500 feet.
The upper flow turns more northerly with available moisture and chances of precipitation decreasing Wednesday and Thursday. Temperatures during the extended forecast period will be near normal for early December.
Daily Forecast:
Tonight: Mostly cloudy, with a low around 33. Light and variable wind.
Friday: A 20% chance of rain then partly sunny, with a high near 48. Wind NW 6-10 in the afternoon.
Friday Night: Patchy fog after 2 a.m. Otherwise, increasing clouds, with a low around 29. Diminishing NW wind.
Saturday: A 30% chance of rain after 5 p.m. Mostly cloudy, with a high near 44. Light wind.
Saturday Night: A chance of rain and snow before 8 p.m., then a chance of snow. Mostly cloudy, with a low around 28. Light and variable wind. Chance of snow is 30%. New snow accumulation of less than a half inch possible.
Sunday: Mostly sunny, with a high near 43.
Sunday Night: Mostly clear, with a low around 25.
Monday: Mostly sunny, with a high near 43.
Monday Night: A slight chance of rain and snow after 11 p.m. Mostly cloudy, with a low around 30. Chance of precipitation is 20%.
Tuesday: A chance of rain and snow before 11 a.m. Mostly cloudy, with a high near 43. Chance of precipitation is 30%.
Tuesday Night: Partly cloudy, with a low around 27.
Wednesday: Patchy fog. Otherwise, mostly sunny, with a high near 42.
Wednesday Night: Partly cloudy, with a low around 26.
Thursday: Partly sunny, with a high near 43.
Stay connected right here for updates to my forecast for the chance of snow in the valley!
