The Treasure Valley is in for a dangerous stretch of heat this week, with temperatures climbing to 104 degrees Friday as the upper-level ridge over the Great Basin builds to maximum amplitude. In the meantime, increasing monsoon moisture will bring a significant thunderstorm and flash flood threat to the central Idaho mountains Wednesday before the pattern dries out heading into the weekend.
Sizzling heat and mountain storms return in Scott Dorval's video forecast
Temperatures in the Treasure Valley will remain near 100 degrees today before a slight moderation Wednesday as increased cloud cover and monsoon moisture keep temperatures a few degrees cooler. Patchy smoke from Oregon wildfires will continue to impact the valley through the week, with some improvement each afternoon as daytime heating mixes out smoke near the surface. Northwest surface winds will transport smoke back into the area each night.
The bigger story for the Treasure Valley this week is the heat building Thursday and Friday. As the upper-level low moving up the Pacific Northwest coast shifts the flow to southwesterly Thursday, temperatures will climb back to near 100 degrees. By Friday, the upper high over the Great Basin will build to maximum amplitude, pushing Treasure Valley highs to 104 degrees with 90s reaching as high as 5,000 feet in the mountains. This will be dangerous heat, and residents should take precautions to stay cool, stay hydrated, and check on vulnerable neighbors and family members.
For the central Idaho mountains, Wednesday will be the most significant weather day of the week. A shortwave trough will aid convection Wednesday afternoon and evening, with a 40 to 90 percent chance of showers and thunderstorms over the central Idaho mountains. Deep moisture and expected slow storm motion will result in the potential for heavy rain and flash flooding, especially over burn scars and steep terrain including the Wapiti burn area. A Flash Flood Watch has been issued for the Wapiti burn area from noon to 9 p.m. Wednesday. Gusty outflow winds of 40 to 50 mph are also possible from stronger storms. The Treasure Valley will see less than a 20 percent chance of precipitation Wednesday.
Hot and dry weather will continue through the weekend and into next week as the upper high dominates and most of the monsoon moisture shifts east of the region.
Tonight
Patchy smoke. Partly cloudy, with a low around 72. Northwest wind 10 to 15 mph becoming light and variable after midnight.
Wednesday
Patchy smoke. Partly sunny and hot, with a high near 95. Light and variable wind.
Wednesday Night
Patchy smoke. Mostly clear, with a low around 69. Wind becoming light.
Thursday
Patchy smoke before 7am. Sunny and hot, with a high near 102. Light wind.
Thursday Night
Mostly clear, with a low around 72.
Friday
Sunny and very hot, with a high near 104.
Friday Night
Mostly clear, with a low around 68.
Saturday
Sunny and very hot, with a high near 101.
Saturday Night
Mostly clear, with a low around 66.
Sunday
Sunny and hot, with a high near 96.
Sunday Night
Mostly clear, with a low around 65.
Monday
Sunny and hot, with a high near 98.
