Wednesday, August 25, 2010

Major Change

For the last few days the weather over the Northwest has been warm and sunny...nearly perfect for outdoor activities. The only negative of the warm, dry weather is fire..and if you look at this evening's visible satellite image you can see the smoke from two large fires over northern Oregon. Plus lots of low clouds along the coast, with a sliver entering the Strait of Juan de Fuca.


Here is a summary of the temperatures of the last 4 weeks versus the normal highs and lows. Pretty normal pattern, with periods of warmer and cooler than normal temps--average out the period, it all is close to normal. There is a good lesson in this--daily temperatures are rarely normal!

A major transition is now occurring and you can expect MUCH cooler weather and the return of some showers for the next 4-5 days. A weak front is now approaching the coast, and the thermal trough, which has been sitting over or just to the east of the western lowlands is rapidly moving eastward. The pressure gradient has turned onshore and cooler air will be moving in overnight. But this will not be like a strong marine push, the decline will be gradual overnight and the first half of Thursday. Here are the pressure patterns for today and tomorrow ... very different indeed.

Aloft the temperatures will be around 20F cooler tomorrow ... you will notice it.

And as the front moves through and the coastal winds turn westerly, a Puget Sound convergence zone will form. As a result the models are predicting a band of precipitation over central Puget Sound late tomorrow afternoon and into the evening (see graphic). Lets see if they are right!

Finally, there have been some ultra-high temps over the inland portions of California, with the warmth extending into Oregon (see graphic). Over 105F in the central valley and over 110F over the SE part of the state. And I might note that nearby Medford, Oregon got to 105F and Redmond, OR a hot 100F! In contrast, the NE U.S. is now cool, with temps in the 70s.

9 comments:

WanderChow said...

Looks like the marine push is going to be fashionably late. It's clear as a bell here, and the moon and Venus look spectacular this morning!

JayDee523 said...

Cliff:

Wednesday evening the fire in the Olympics rekindled and the smoke trailed off in a thin stream to the NE as a perfect illustration of the winds aloft. With the cooler weather, I expect this might be it's last gasp.

windlover said...

I know that long range forcasts are rarely accurate but do they even hint at another warm spell? Or is this it for the summer and we are now into fall?

Josh said...

"The only negative of the warm, dry weather is fire"

This is fire season. And over all it has been a tamed one.

Smokey the Bear killed our forest..

Targhee said...

Any ideas what happened in Spokane early Thursday? Temp went from 69 to 96 in one hour around 9am, then back down to the low 70s. Warm downdraft? I would have been suspicious if it wasn't the official NWS station.

Cliff Mass Weather Blog said...

Targhee,
There was a serious data problem...clearly an error..cliff

Tom said...

Glad I skipped work on Wednesday and went sailing! The wind wasn't super good on Lake Washington, but I got about 4 knots out of the boat, better than sitting still flopping. Hope I get another chance to sail in September. Disappointing summer.

smokejumper said...

I forget the exact date, but it was my only year at CWU, probably the most bizarre meteorologicial event i will ever witness.

Anyway, it was blazing hot in the afternoon. Strong convection overnight, and Hanford jumped 25 degrees in one hour to 100+ degrees at 1am. In Ellensburg we jumped 20 degrees to the upper 90's in 15 minutes. Little research I did for it, all I found was its called a "heat burst."

So it is possible, but I saw multiple observations backing mine up. Just one site, probably just an error.

Eric S. said...

Hi Cliff -

My wife asked the question to me today, "how many days over 70 have we had this summer vs. a typical summer?" and I had no idea where to look up such data...except your blog! Can you point us to a source of this kind of information?

Thanks,

Eric S.