Tuesday, May 18, 2021
May 18, 2021

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Air quality improves significantly as weather system approaches

Long smoky period to end with possible thunderstorms, flash flooding in burn areas

By , Columbian Metro Editor

Forecasters are seeing the light at the end of a long, smoky tunnel for Southwest Washington as a shift in weather patterns begins to take hold.

Fine particulate pollution (PM 2.5) levels reported by the Environmental Protection Agency started the day at just over 400 in Vancouver, well into the “hazardous” range, and slowly fell to about 350 until 1 p.m., when levels dropped to 282, which is “very unhealthy” and then to 190, in the “unhealthy” range, as of 4 p.m. At 5 p.m. Vancouver’s level was 183.

Air quality levels in Yacolt remained at about 190 throughout Thursday, which falls into the “unhealthy” range, according to the Environmental Protection Agency’s site, airnow.gov.

Westerly winds of up to 9 mph were recorded at Pearson Field and visibility improved, according to the National Weather Service.
The transition from this week’s smoky calm to fresher air will be dramatic, not just because of the significant improvements expected. The storm system could include strong thunderstorms and a chance of flash flooding in burned over areas.

The National Weather Service is predicting showers and even a few thunderstorms will move through the area in the next 24 to 48 hours, helping to clear out much of the wildfire smoke that has lingered in the area for more than a week.

A smoke forecast from the Washington Department of Ecology predicts air quality will improve today and Saturday.

Pollution levels began to fall in Vancouver on Thursday afternoon just as winds began to pick up from the west, breaking an extended period of calm air and temperature inversions that trapped wildfire smoke at lower elevations.

Widespread showers are expected to linger over the area through tonight with a chance of a few thunderstorms, but those storms are not expected to be severe.

Rainfall totals were forecast at 0.30 to 0.85 inch of rain through Friday with higher amounts possible for locations that experience heavier thunderstorms.

Forecasters say the weather system will provide much-needed relief from the region’s dense smoke, though some may linger.
“Do not expect all of the smoke to be gone, but rather a noticeable improvement,” a forecast discussion said.

More typical summertime weather is expected to follow, with mild temperatures and northwest winds over the weekend before another storm system brings a chance for rain later next week.