Omega block weather locks in pattern of rain, damaging winds and hail in the Pacific Northwest

A rare severe storm threat emerged in the Pacific Northwest on Thursday, with the primary threats being damaging hail and winds.

Americans are bracing for another round of severe weather in the Pacific Northwest, after an Omega block weather pattern settles across the U.S.

An Omega block weather pattern occurs when a large ridge of high pressure is sandwiched between two areas of low pressure, forming the Omega shape.

WHAT IS AN OMEGA BLOCK?

An Omega block has anchored across the country and will keep the East and West coasts in a weather pattern.

An area to monitor is the Pacific Northwest, where a rare severe storm threat emerged on Thursday, with the primary threats being damaging hail and winds.

"This region historically sees very few severe storms in May; in fact, parts of the inland Northwest have not seen a severe thunderstorm watch issued in over three years," the FOX Forecast Center said.

FLASH FLOOD THREAT REIGNITES ACROSS THE SOUTHEAST AFTER TEXAS WATER RESCUES AS RAIN BRINGS DROUGHT RELIEF

Meteorologists are monitoring an upper-level low moving over the West Coast, which could trigger severe storms in northern portions later this evening.

Pleasantly sufficient heat and moisture will combine to allow severe storm development, bringing a threat of potentially damaging winds and hail, along with a marginal tornado threat.

This line of storms is expected to move into eastern Washington late Thursday evening.

By Friday, the severe threat will shift out of the Pacific Northwest and into the Northern Rockies, where a more defined area of low pressure will begin to develop.

ANOTHER GLOOMY, RAINY WEEKEND ON THE WAY FOR NEW ENGLAND TO ROUND OUT SPRING

Parts of western Montana are under a Level 1 out of 5 severe storm threat, with a higher chance of damaging hail and winds.

Populated locations such as Boise, Idaho, are under a Special Weather Statement as these conditions continue to develop.

HOW HIGH PRESSURE AND LOW PRESSURE DRIVE THE WEATHER

A low-end flash flood threat will also need to be monitored, as these severe storms could produce high rain totals starting Thursday and continuing through Friday to start the weekend.