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The reason why lightning strikes are rare in the PNW

PORTLAND, Ore. (KOIN) — Over 1,300 lightning strikes brightened the dark skies of western Oregon and Washington early Thursday morning.

A parade of thunderstorms marched east to west just before sunrise. Heavy rain, loud thunder, and of course, lightning could be found across the region. The National Weather Service out of Portland counted nearly 1,000 cloud-to-cloud lightning strikes Thursday morning over southwest Washington and northwest Oregon.

The count for cloud-to-ground strikes was significantly less. Only amounting to roughly 300 strikes. There’s a reason those numbers are so different.

The National Weather Services recorded nearly 1,000 cloud-to-cloud and 300 cloud-to-ground lightning strikes over southwest Washington and northwest Oregon Thursday morning, May 4, 2023

The atmosphere over the Pacific Northwest is able to produce cloud-to-cloud lightning much easier than it can produce cloud-to-ground lightning. Internal cloud lightning takes less energy because the water vapor that makes up clouds is a great conductor of electricity.

Outside of the cloud, the atmosphere is much direr. That dry air acts as a good insulator. It takes more energy to push the electrical charges associated with lightning through that insulated layer.

Cloud-to-cloud lightning is more frequent than cloud-to-ground strikes

Overall, lightning storms or usually infrequent in the Pacific Northwest. That’s in part to the mild conditions the Pacific Ocean provides for the region.

Thunderstorms average frequency by day during the warmer months in Portland

On average, Portland typically only sees one day of thunderstorm activity during the warmer months. So, thunderstorms do happen in the Pacific Northwest, but they are less frequently seen than in places east of the Pacific Northwest.