Monday, August 30, 2010

Unusual August Rainfall


An unusually heavy rainfall event for August is going to strike our region during the next two days, and its coming from the west and northwest--not the usual southwesterly direction of our big winter rains. Take a look at the latest satellite image above--see those clouds offshore?--they are the leading edge of the first a several, unusually strong, late summer disturbances that will strike soon.
How wet? Here are the latest 24-h rainfall total predictions for Washington State ending 5 PM Tuesday and Wednesday (click on the images to get larger images). The coast and western side of the Cascades get hammered, with 1-2 inches being widespread. Some locations may get 2-3.5 inches. The lowlands could receive .5 to 1 inches over the next two days. My advice: you won't have to water for a few days!



Here is the computer forecast of water vapor in the atmosphere (total from the surface to the upper atmosphere) for 11 PM tomorrow. See the extraordinary long plume stretching westward into the Pacific? If that graphic was larger you would see the tail dip down into the subtropics!


Later this week, a ridge of high pressure moves in, the thermal trough moves northward, and we get a few days of warmer weather. But the latest runs suggest it won't last. Sorry. The good thing is that this event will severely damp down the potential for wildfires.

13 comments:

Diary of a cat household said...

In Aug 1982 just before I started college, we went through a period of really wet and cold weather. That fall was spectacular, cool and crisp.

Blake said...

And we quickly race to #15. Worst summer of the past 15 years. Here's to a dry September and some good biking to work weather.

RobertSeattle said...

Turn off your sprinkler systems! One of my pet peeves is seeing a sprinkler system runngin WHILE it is raining. Get off your keister and turn your system off for a couple of days.

TVN said...

Blake - are you overlooking the summer of 1999? It rained every weekend that summer. It finally dried out for a nice indian summer
(and a beautiful wedding for yours truly)....just in time for us to leave and have our plants die. : )

Anyway, the weather kinda works for me. The kids start school tomorrow and it sets the mood for fall.

natchrl8r said...

Actually, I think this summer is an improvement on 2 years ago and I can remember much worse summers in the last 15 years. I think it was summer of 1997 or 1998 that we only had about 3 weeks of dry weather. I've always maintained that Indian Summer is the real, more reliable summer in the PNW. I've learned not to expect East Coast or California summers and am mostly pleased with what we get.

Chris and Amy's story said...

Cliff, you weren't kidding about the rain! It's wet out there!

smokejumper said...

Any record low highs recorded today in the state? It got to 60.8 at my house, average 83.

The radar shows an interesting story during these winter storms, I mean summer. I thought you were way too optimistic about the rainfall, but once the orographics kicked in this afternoon, it dumped in the mts. Right on again.

smokejumper said...

Sorry, but I usually look upstream to see whats ahead. But I just noticed this storm on us now is gonna spare the US billions of dollars dollars and countless lives. Incredible.

Blake said...

I guess the part that drives me a little crazy is the 'range of possible' which gets up my false hopes. I can remember stretches when we had nothing but sun for 15 days in a row. Now that's on the outer range of possible, but when is the last time we had a persistent ridge like that?

You're may be right we've had worse summers recently, but my gauge of 'worse' is lack of sun, not cool temps or rain. The sunshine is what is missing this year. The rest of the year, I'm fine with our weather. I love the light we get year round with our latitude and cloud variations.

I'm coming realize I need a week long vacation in E. WA sometime in early August to guarantee some real summer weather.

Trey said...

55.8 mm / 2.2 inches of rain up here in Vancouver (BC) yesterday - and that was at YVR, which is generally far from the wettest spot. Pretty impressive for August - any one-day records broken? Now we just need that much moisture in November when the freezing level is low...let's go La Nina! :)

Jenny said...

Is there a way to find out how many days it managed to get over 75 this summer? And how this summer compares to the past in that statistic?

Matt said...

Portland had the coldest summer in 15 years. and most rain in june, ever, so, people saying 'the worst' in 15-20 years aren't exactly having selective memory--the data backs it up.

http://www.westernusawx.info/forums/index.php?showtopic=30415

Bham_Guy said...

Jenny,

SEA recorded 28 days of 75° or warmer this past June, July and August. I'm not sure how it stacks up to previous summers, but I do know that the average temp was slightly below normal.