Scattered thunderstorms are developing across southern Oregon and southwest Idaho this afternoon, bringing the threat of gusty outflow winds up to 50 mph, small hail, and brief heavy rain, before a prolonged period of dangerous heat builds through the week with temperatures approaching or reaching triple digits by Friday.
Triple-digit heat for the weekend in Scott Dorval's video forecast
An upper-level disturbance is spinning over southeast Oregon this afternoon, creating a split in conditions across the region. Areas north and east of the disturbance, including the Baker Valley in Oregon and the Cascade and McCall areas in Idaho, have seen clouds and light rain that have kept temperatures down and the atmosphere more stable. However, skies have cleared south of the disturbance and the atmosphere is becoming very unstable across southern Oregon and southwest Idaho. Scattered thunderstorms are developing and will spread north and east through the early evening hours. These storms are expected to produce gusty winds up to 50 mph, small hail, and brief rain. Thunderstorm activity should subside overnight, with about a 20 percent chance of isolated thunderstorms developing again Tuesday afternoon.
Wednesday will bring generally hot and dry weather with southwesterly winds increasing in the afternoon. Thursday will offer a few degrees of cooling with temperatures near normal, thanks to the passage of an upper-level shortwave. Breezy conditions will persist through Thursday with afternoon gusts of 20 to 35 mph across southern Idaho. These breezy conditions, paired with minimum afternoon relative humidity values around 15 percent in the lower elevations, will lead to elevated fire weather concerns for southwest Idaho.
A Four Corners ridge will dominate the rest of the extended period, leading to a week of hot and dry conditions. Valley high temperatures will reach the upper 90s Friday with some locations approaching triple digits. With the area on the periphery of this ridge, even a slight westward shift could allow many lower elevation sites to hit triple digits. Monsoonal moisture could begin working its way around the ridge by Monday, supporting an increasing risk of thunderstorms.
Patchy smoke will be a concern Tuesday morning as a result of ongoing fire activity in the region.
Tonight
Areas of smoke. Mostly clear, with a low around 64. Northwest wind 5 to 9 mph becoming calm after midnight.
Wednesday
Patchy smoke between 9am and 10am. Sunny and hot, with a high near 99. Light and variable wind becoming northwest 6 to 11 mph in the afternoon.
Wednesday Night
Patchy smoke before midnight. Mostly clear, with a low around 62. Northwest wind 6 to 11 mph, with gusts as high as 22 mph.
Thursday
Sunny and hot, with a high near 95. Northwest wind 5 to 10 mph.
Thursday Night
Clear, with a low around 60. Northwest wind 5 to 10 mph becoming light and variable after midnight.
Friday
Sunny and hot, with a high near 101.
Friday Night
Clear, with a low around 64.
Saturday
Sunny and hot, with a high near 101.
Saturday Night
Mostly clear, with a low around 66.
Sunday
Mostly sunny and hot, with a high near 100.
Sunday Night
Partly cloudy, with a low around 67.
Monday
Mostly sunny and hot, with a high near 99.
Monday Night
Partly cloudy, with a low around 67.
Tuesday
Mostly sunny and hot, with a high near 99.
