Cooler Temperatures, Rain and Thunderstorms Possible in Southern Oregon

Medford, Oregon- An incoming Pacific front and upper trough are expected to bring unseasonably cool temperatures, widespread rain, and chances for thunderstorms across southern Oregon and northern California through the weekend, forecasters said Friday.

Satellite imagery shows the system moving in from the northwest, with rain expected to begin along the Oregon coast Friday evening before spreading into the Umpqua Basin and southern Cascades overnight. Precipitable water values of 1.5 to 2 inches indicate ample moisture with the front.

Rain and showers will develop across southwest Oregon and northern California on Saturday, with embedded thunderstorms possible in the afternoon. The strongest chances for storms, around 20%, are forecast from the western slopes of the Cascades eastward and across northern California. Rogue Valley counties, including Josephine, Jackson and eastern Douglas, have a 5% to 15% chance of thunderstorms.

Rainfall totals are expected to be light to moderate overall. Most areas could see 0.10 to 0.30 inches, with higher amounts of up to 0.50 inches possible in the coastal mountains of Curry, Coos and Douglas counties and across the southern Oregon Cascades. Localized amounts up to 1 inch may occur east of the Cascades and in northern California where thunderstorms develop.

Showers will continue into Sunday morning, mainly east of the Cascades and in northern California. Instability is expected to persist, bringing a 15% to 35% chance of isolated to scattered thunderstorms Sunday afternoon and evening, particularly in Lake, eastern Klamath, eastern Siskiyou and Modoc counties.

Cooler conditions will hold through the weekend, with slightly stronger afternoon and evening breezes possible east of the Cascades. Forecasters said any thunderstorms that form are more likely to produce rainfall due to higher moisture levels in the atmosphere.

By Monday, a shift to southwest flow will bring gradual drying and warming. Highs are forecast to return to seasonal levels Monday before climbing above normal Tuesday through Thursday. Western valleys are expected to see temperatures in the 90s by midweek, with some lower Klamath River valley locations possibly reaching the low 100s. Valleys east of the Cascades will warm into the upper 80s to low 90s.