September 12, 2010

Go South for Sun! Wine weather.

During the fall, the jet stream and its associated weather strengthen and move southward. As a result our region gets increasingly "clipped", starting with the north. Today and late yesterday are a classic cases.

A weak front is now bringing clouds, rain, and cooler temperatures north of Seattle, while to the south it is dry and much warmer. Head to Portland and you can enjoy a warm sunny day. Here is the latest weather radar image:

The northern rain is apparent. You don't see much rain over the mountains...but don't believe it. The Camano Island radar is substantially blocked by the lower foothills and we can't see what is happening at higher elevations very well. You can also see a bit of the Olympic Mountain rainshadowing.

Here is the new visible satellite picture. Clear in Portland and over SE Washington. And if you look closely you can see wave clouds east of the Cascade crest.
Eastern Washington needs all the sun it can get so the grapes can ripen. With a cool spring and late summer, the maturation process is well behind according to some reports:

Interestingly, the author describes 2010 as a meteorological "perfect storm" for wine, with periods of above normal and below normal temperatures and excessive precipitation that leads to mold and mildew. The quality of the NW wine crop is not simply of academic interest for many of us!

Here is are the temperatures at Pasco the last two weeks. Most days are are not getting to normal and nighttime temps are dropping into the low 40s. And the downward trend is very clear.

After our front moves through today, there should be an improving trend for a few days. But let me be honest: current forecast models indicate a very wet weekend coming up. That could change of course as we get closer, but this solution has been quite stable. If still there on Wednesday's runs, it will probably be a reality.


  1. favorite time of year...Fall in Western WA. :)

  2. Unusual Sept. storm taking shape. Busted extended forecast. Justifiably it was a hard pattern to predict.

    PS. Its not fall yet!

  3. Hey Cliff - We're getting married at Lake Crescent on the Peninsula this weekend! Is there any hope of sun breaks or all doom and gloom?


  4. Planning a wedding in Lake Crescent this weekend (wet?) - but for anyone in general- where would you look for mid term local forecasts (4-7 days out) to supplement the dialog in the NWS discussion? I read also the UW probability page.

  5. further, might Mt. Olympus produce a rain shadow to the north if the rain were moving south to north per a low pressure area to the west???

  6. @smokejumper...

    Well, it's not officially fall yet...but just like Summer starting on July 5th in most of Western WA...Fall starts a little bit early some times :)

    Go Fall!


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