Weather with Cliff Mass
9:18 am
Fri September 23, 2011

Feels like the East Coast … but we’ll go back to NW weather soon

It’s the first day of fall, but you can’t trust the calendar to tell us what kind of weather we’ll be having. … So, we turn to Cliff Mass and KPLU’s Keith Seinfeld to give it to us straight.

First, it’s the water vapor in the air covering us like a blanket that will keep us warm and humid today and tomorrow. But it all changes again on Monday. And with a new radar station coming online on the coast, Mass says we’ll be able to see our future weather much more clearly.

Right now, says Mass, a University of Washington Professor of Atmospheric Sciences and KPLU’s go-to forecaster, the jet stream is capturing warm moist air from the tropics and subtropics, and this "atmospheric river" is directing it up into our region, with British Columbia getting the most of the action in terms of torrential rains in some areas.

In Washington, for now, the moisture is stuck out on the coast, “but the whole thing changes on Sunday …. The jet stream moves in and we start getting into the real active weather systems.”

Expect temperatures in the 60s with substantial rain and wind on the coast and the interior.

New tool for forecasts

Mass says a major revolution in Northwest weather prediction has occurred. A new coastal radar has been installed on Langley Hill just north of Hoquiam.

“It’s extraordinary,” Mass says. “For the first time we can see off shore. Up to now, the radars we had in the Northwest were on Camano Island and in Portland, and their beams were blocked by the coastal mountains. And also they were pretty far from the coast, so we were blind. We couldn’t see the details of the weather systems approaching.”

That’s all changed. Think of it as a meteorological version of a medical CT-scan -- which can see details of weather systems 200 to 250 miles off shore.

“Although these radars (on Camano and near Portland) represented a major improvement from the nearly radarless situation before, some major problems became apparent. A huge issue was the lack of radar coverage over the coastal zone and offshore. ... Furthermore, there was no coverage over the wet, windward sides of most of the regional coastal mountains, hampering prediction of flooding. And, of course, coastal residents lacked the benefits of being able to use the radar for planning business and recreational activities.”

That’s all changed with the new radar, Mass explains in detail in his story “Langley Hill Coastal Radar:  The Latest Addition to the National Weather Service Doppler Radar Network.

On the Web:

The weekly KPLU feature "Weather with Cliff Mass" airs every Friday at 9 a.m. immediately following BirdNote, and repeats twice on Friday afternoons during All Things Considered. The feature is hosted by KPLU’s Health and Science reporter Keith Seinfeld. Cliff Mass is a University of Washington Professor of Atmospheric Sciences and renowned Seattle weather prognosticator.