PORTLAND, Ore. (KOIN) – A rumble of thunder and a downpour is in the forecast Tuesday. What’s the deal with the shaky weather? A trough with cold unstable air is pushing across the Pacific Northwest. An associated area of low pressure is churning around in the Gulf of of Alaska, closer to Haida Gwaii.

The tilt of the trough will favor the development of dynamic rain showers. The Portland metro area may have a moment where the rain is coming down hard, with small hail embedded. This is more likely in the afternoon than in the morning. However, you will want to be prepared for a passing shower for your morning commute.

Now would be a good time to swipe through the forecast zones slideshow below.

Most locations Tuesday are going to be cooler than the average for late April. Expect temperatures in the lower 50s up and down the Oregon coast from Newport to Astoria. Scattered showers for Tuesday morning and the afternoon, with an isolated thunderstorm possible.

The wind is going to be running out of the southwest around 10 to 15 mph with gusts to 20 mph. The Willamette Valley is going to warm to the mid 50s — nearly 20 degrees cooler than the temperatures on Sunday. We will be running around 10 degrees cooler than the average in the afternoon.

Due to that cold air aloft, it may not take too much work to get some hail coming down to the surface. A reminder that if you hear thunder, head inside for 20 to 30 minutes as the storm passes. The thunderstorm threat will mainly hold west of the mountains.

Speaking of the mountains…are we looking at more snow? We sure are!

It’s cold enough for those snow levels to drop to near the passes. We may get a healthy 1 to 3 inches for the passes. The ski resorts will pick up some more snow for skiing and snowboarding.

This is the most productive spring that we have had in a few years. We will keep the cool showers going this week.