PORTLAND, Ore. (KOIN) – The threat of spring storms builds over northern Oregon and southern Washington Tuesday afternoon. No severe weather is expected Monday or Tuesday, but the chance to see small hail, heavy rain and an occasional bolt of lightning and rumble of thunder is possible. This comes as another spring low pressure system slams into the Oregon and Washington Coast Monday night into Tuesday morning. An unstable atmosphere could give way to stronger storms for some along the Willamette Valley, but increased rainfall amounts and gusty winds will be the biggest concern.