PORTLAND, Ore. (KOIN) — Severe thunderstorms are possible in parts of Oregon and Washington Friday and Saturday. Hail and damaging winds are the biggest threats to those living east of the Cascades.

Storms will start building Friday evening east of the mountains. These storms will be isolated in nature. Quart-sized hail and greater is possible with some of these isolated storms.

Heavy rain will create gusty, strong winds that will likely climb above 35 mph under and near some of these storms. The storm impacts will remain clear of the Willamette Valley and the Portland metro area Friday night and Saturday afternoon.

Hail is the biggest severe weather threat moving towards the weekend.

The chance for severe weather becomes more widespread Saturday. Storms will start building over Central Oregon during the early afternoon hours Saturday. Those storms will track to the north through the afternoon and through the evening.

The threat of lightning, hail, and damaging winds moves north into Washington Saturday.

Heavy rain also brings the chance for minor street flooding and higher river and stream levels as snowmelt adds to the water flow.

Lightning remains the biggest threat to those taking part in outdoor activities Friday evening and Saturday afternoon.

Outdoor mountain enthusiasts should take shelter indoors or in a vehicle if caught outside during one of these thunderstorms. Outdoor activities should be completed by the early afternoon hours as storms start to build afternoon.