The Treasure Valley will experience one more day of unseasonably mild weather Thursday before a Pacific cold front ushers in a cooler, more unsettled pattern for the remainder of November.
Peak warmth arrives Thursday
Wednesday will see increasing clouds with highs near 66 degrees as an upper ridge continues to dominate the weather pattern.
Thursday represents the final day of this extended warm spell, with partly sunny skies and highs reaching 67 degrees. This will be about 15 degrees above normal for mid-November. The breeze will likely increase out of the SE as a system approaches from the west.
The mild temperatures are being maintained by an upper-level ridge over the interior western United States, which has created a weak temperature inversion in the valleys over recent days.
Weather pattern shifts Thursday night
The weather story changes Thursday evening as the ridge shifts eastward and a Pacific cold front moves through the region. Rain chances begin at 20% after 11 a.m. Thursday, then increase to 60% Thursday night as the front arrives.
Light rain will begin in eastern Oregon Thursday morning, then spread eastward into Idaho during the afternoon and evening hours. The Treasure Valley can expect mostly cloudy skies Thursday night with lows around 46 degrees.
Precipitation amounts will generally be light across lower elevations, with most valleys receiving less than 0.10 inches of rain. However, the Boise Mountains and west central Idaho mountains could see 0.25 to 0.60 inches of total precipitation from Thursday afternoon through Friday night.
Mountain snow finally arrives
This system will bring the first appreciable mountain snow of the season. Snow levels will drop below 6,000 feet Friday morning, allowing accumulations of 1 to 3 inches in higher elevations.
The west central mountains have the best chance for meaningful snowfall, with locations above 5,500 feet having a 30-70% chance of receiving at least 4 inches of snow Friday and Saturday. High mountain passes and ridgelines could see 2-6 inches of snow accumulation.
Cooler weekend ahead
Friday brings a noticeable temperature drop as the cold front moves through completely. Partly sunny skies will accompany highs near 57 degrees - about 10 degrees cooler than Thursday. There's a 40% chance of rain, mainly before 11 a.m.
The weekend looks pleasant with mostly sunny skies Saturday and highs near 54 degrees. Sunday starts mostly sunny with highs near 56 degrees, though a 20% chance of rain develops after 11 a.m.
Unsettled pattern continues
The brief break in active weather will be short-lived. Another weather system is expected to move through early next week, bringing elevated precipitation chances from Sunday afternoon through Tuesday.
Sunday night shows a 40% chance of rain with mostly cloudy skies and lows around 37 degrees. Monday continues the unsettled pattern with a 30% chance of rain and partly sunny skies, with highs cooling to 51 degrees.
Tuesday could see highs drop to 47 degrees with a 20% chance of rain and mostly sunny skies, representing a return to near-normal temperatures for late November.
Daily forecast
Tonight: Mostly cloudy, with a low around 43 degrees. Calm wind.
Wednesday: Increasing clouds and unseasonably warm, with a high near 66 degrees. Calm wind becoming ESE around 6 mph in the afternoon.
Thursday: A 20% chance of rain after 11 a.m. Partly sunny, with a high near 67 degrees. ESE wind 6 to 11 mph, with gusts as high as 23 mph.
Thursday Night: Rain likely, mainly before 11 p.m. Mostly cloudy, with a low around 46 degrees. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.
Friday: A 40% chance of rain, mainly before 11 a.m. Partly sunny, with a high near 57 degrees.
Friday Night: Partly cloudy, with a low around 38 degrees.
Saturday: Mostly sunny, with a high near 54 degrees.
Saturday Night: Partly cloudy, with a low around 38 degrees.
Sunday: A 20% chance of rain after 11 a.m. Mostly sunny, with a high near 56 degrees.
Sunday Night: A 40% chance of rain. Mostly cloudy, with a low around 37 degrees.
Monday: A 30% chance of rain. Partly sunny, with a high near 51 degrees.
Tuesday: A 20% chance of rain. Mostly sunny, with a high near 47 degrees.
Stay connected right here for updates to my forecast of a big weather change ahead.
