PORTLAND, Ore. (KOIN) — Warmer and sunnier skies will help build thunderstorms over the Cascades and Willamette Valley Wednesday afternoon.

Mostly cloudy skies will keep temperatures mild Wednesday morning. Clouds will slowly clear throughout the day as temperatures warm into the low- to mid-70s.

Warmer afternoon temperatures will help build early evening thunderstorms over the Cascades. Those potential storms will track west through the late evening hours. A bolt of lightning and a clap of thunder is possible for some Wednesday.

No severe weather is expected with Wednesday’s storms. Rain accumulation will be minimal for most, but totals could near three-quarters of an inch in areas with some larger storm cells. These cells will be isolated in nature Wednesday.

Thursday’s storm potential becomes more widespread. Thursday’s showers will drop temperatures nearly 10 degrees from Wednesday to Thursday. Afternoon highs will stay slightly below average through the weekend.

KOIN 6 Meteorologist Josh Cozart shares Portland’s extended forecast as thunderstorms and cooler temperatures return to the region

Cooler and wetter weather will be beneficial to those who suffer from seasonal allergies.

Portland’s pollen counts lower as rain returns to the forecast this week

Wednesday and Thursday’s thunderstorm activity will help clear skies around Portland of pollen particulates.