Maybe you felt a spark as you walked over carpeting and touched a doorknob. Or perhaps you noted how arid the soil was when you went out to do some gardening. These are signs of low relative humidity in the air. And Western Washington has experienced extreme levels of it — on several days this past month.
KNKX weather expert Cliff Mass says it’s been so dry, he coined a new term for it: "dry storm."
“We’ve had a few occasions this week, where we’ve had really, really low humidities — I mean extraordinarily low,” Mass said. “The lowest we’ve had in six months in some places.”
He says what’s happened is that high pressure and cool air have moved into the area around Montana. This creates offshore flow in Washington, air flowing into us from the east. It’s dry when it reaches the Cascade Mountains, but gets compressed and even dryer as it sinks and flows down the slopes into Western Washington. Extreme examples of this happened on Monday and Thursday this week.
“The relative humidity dropped to between 15 and 20 percent — in some places even lower,” Mass said.
And, he says, the dry air combined with warm temperatures go hand in hand with very high levels of tree pollen: “The pollen counts have been amazingly high this week. And having warm weather just makes it worse.”
With more of this kind of weather pretty consistently in the forecast for the next week, Mass says we’re on course to set a record. It’s been extremely dry this month already.
“If this keeps up, we may end up with one of the driest Aprils on record,” he said.