Upper level low spinning clouds, isolated t-storms in Tuesday

Tri-Cities weather – May 2, 2023

A strong upper level low pressure system centered near San Francisco this morning is driving the weather pattern over the Pacific Northwest today. In the Columbia Basin, this is likely to produce intermittent clouds and sun along a fairly narrow band.

Previously, temperatures were forecast to reach into the mid 80s this afternoon but with the presence of the cloud cover we may be limited to around 80°F for a high in the Tri-Cities. Areas to the north, such as Moses Lake and Ritzville, may get a bit warmer as they spend more of the day under sunny skies.

The upper level low is pulling warm moisture to the region all the way from the Gulf of Mexico. Despite traveling over the Rocky Mountains, this increased humidity is enough to produce scattered thunderstorms in Inland Northwest mountains and isolated storms in lowland areas.

This pattern is similar to last night when a few thunderstorms popped up in the area. A couple hundredths of an inch of rain were observed in a few spots, such as near Irrigon and Sunnyside, thanks to brief downpours. That sort of thing may happen again this evening and/or tonight, though I think most will remain dry.

The best chance of thunderstorms appears to be Wednesday and Thursday afternoons. The upper level low gets caught up in the broader flow pattern Friday, sweeping over the Pacific Northwest for a chance of rain showers into the weekend.

The featured image is 500 mb (about 18,000 feet up) heights and wind at 07:00 Tuesday showing the jet stream coming into the Pacific Northwest from the south. Source: Windy.