A Heat Advisory remains in effect for the Treasure Valley and Snake River Plain through 9 p.m. tonight as the hottest temperatures of the week arrive, with highs reaching the upper 90s to 105 degrees in the lower valleys.
Smoke & sizzling heat continue this week in Scott Dorval's video forecast
The central United States upper-level ridge continues to build northwest across the Great Basin, driving the most intense heat of the week across the region today. Southerly flow aloft is transporting deep monsoon moisture into the region, with moisture values well above the 95th percentile. Breezy conditions will develop late today with gusts of 15 to 30 mph across the Treasure Valley and central Idaho. Areas of wildfire smoke will be a recurring concern through the week, with northwest surface winds continually transporting smoke back into southwest Idaho each day.
Temperatures will be a few degrees cooler Tuesday as monsoon moisture continues to increase. The Treasure Valley and lower Snake River Plain will remain mostly dry, though areas of smoke will persist. The west-central Idaho mountains will see the best chances for showers and thunderstorms Tuesday.
By Wednesday, moisture values will rise to near the 99th percentile. An embedded shortwave trough will interact with this moisture, increasing shower and thunderstorm coverage across the region. The higher terrain across far southwest Idaho will see a 20 to 40 percent chance of precipitation, with less than a 20 percent chance in the lower valleys including the Treasure Valley. With deep moisture in place and slow expected storm motion, any thunderstorms that develop will be capable of heavy rain and flash flooding, especially over burn scars and steep terrain. Temperatures will remain similar to Tuesday.
The pattern will dry out Thursday as upper flow shifts and pushes the monsoon moisture eastward out of the region. The main upper high will also expand westward, effectively preventing more monsoon moisture from reaching the area. Hot and dry conditions will then dominate through the weekend, with temperatures climbing back to the low 100s by Friday. A breezy and cooler period will begin next Monday as an upper trough off the northwest coast moves inland across Washington and northern Oregon.
Tonight
Patchy smoke. Increasing clouds, with a low around 72. NW wind 5-15 diminishing later.
Tuesday
Areas of smoke. Mostly cloudy, then gradually becoming sunny and hot, with a high near 98. Light wind.
Wednesday
Partly sunny and hot, with a high near 97. Wind NW 5-10.
Thursday
Sunny and hot, with a high near 101.
Thursday Night
A 20 percent chance of showers and thunderstorms before midnight. Mostly clear, with a low around 69.
Friday
Sunny and hot, with a high near 102.
Friday Night
Clear, with a low around 68.
Saturday
Sunny and hot, with a high near 99.
Saturday Night
Mostly clear, with a low around 65.
Sunday
Sunny and hot, with a high near 98.
Sunday Night
Mostly clear, with a low around 64.
Monday
Sunny and hot, with a high near 99.
