Thursday, October 8, 2009

Dust Storm Redux?


A dry weekend is ahead, but there is some interesting meteorological action in our future. A fairly strong cold front followed by rapidly increasing pressure will push into eastern Washington tomorrow...with several pulses of cold air and high pressure over the weekend. Take a look at several forecast charts over the next few days--they show sea level pressure, surface winds, and temperature (with blue being cold). Notice how the cold colors push in as the cold front moves southward.

This surge of cold air will cause fairly strong winds from the north and northeast...but not as strong as last Sunday. Winds will surely reach 20-30 mph, with some stronger gusts--and such winds are strong enough to raise dust.

The problem is that many farmer's have tilled the soil in preparation for next season, and the ground is very dry. As noted above, it takes a 20-30 mph winds to raise significant dust and we will probably attain this--with the strongest winds probably on Sunday. The Spokane NWS office has already put out a warning for poor visibilities in blowing dust. So be careful if you are driving east of the Cascades this weekend.

If you look carefully at the forecast pressure maps above you will note that there is a tongue of particularly high pressure over the eastern slopes of the Cascades. This is caused by cold-air damming whereby cold air is pushed up over the eastern slopes. Strong easterly winds should also pour out of the Fraser Valley..so Bellingham and NW Washington will also get strong winds. But no dust.

6 comments:

Kevin Purcell said...

Cliff:

What do you think the overnight lows will be in the Puget Sound lowlands on Sat and Sunday?

The meso models seem to be showing around 0C/32F but the NWS in the Forecaster Discussions seems to think the models are being rather too low and they're current lows are more than 10F (5C) above that in Seattle.

natchrl8r said...

NWS forecasts are not mentioning wind or dust at all. I don't recall them mentioning last weeks winds either, which resulted in a power outage in Bellingham. On top of the frigid cold, wind and dust effectively cancel my camping trip to the Tonasket Barter Faire. I always appreciate the heads up!

Avalanche said...

You're right about the cold air damming on the eastside of the Cascades. Glad to see it in your book. It really is the main reason why it snows as much and stays around like it does around here. (NW of Yakima). We still have apples on our trees and people are working fast today to get them off. Possible lows of 22-24 will damage a lot of apples.

Josh said...

Looks like El Nino is setting in on The West Coast. Northern Cal looking like its getting ready for a unseasonable big storm early next week.

Jim said...

Looks like it's time to protect a few plants from freezing in this zone. By the way, I was seeing an interesting article about clouds in "Wired" magazine:
"Weather Geeks Champion New Armageddon-Worthy Cloud" http://www.wired.com/science/planetearth/magazine/17-10/st_clouds
Check it out, Weather Geeks!

mainstreeter said...

It didn't get as cold overnight as predicted, at least for Saturday morning. Lows were only in the upper 30's for Yakima. It was cloudy here most of the day Friday. It's predicted to only get up to 50 today. We'll see. Still cloudy No real wind event either.