When I was a kid, kosher wine pretty much meant the standard non-Pesach corn syrupy-sweet Manischewitz. In California, friends celebrating Passover (which requires four glasses of wine to be consumed during the course of the seder) introduced me to the wide variety of excellent, and non-sulfide containing, kosher wines. I discovered not only excellent Israeli kosher wines, but California kosher wines from Herzog Cellars and others. California wineries produce a wide variety of white and red wines (traditionally, seders usually involve red wines, but Californians may be less orthodox in that respect).
I wondered if Washington produced kosher wines, and set about to find out. But, I hear you ask, what does it mean for a wine to be kosher?
In order for a wine produced outside of Israel (where the rules are much stricter) to be kosher all the production of the wine after the grapes are picked must involve handling only by sabbath-keeping Jews under the direction of a rabbi or Kashrut trained supervisor.
No work, at all, may be done on the sabbath. That means from sunset to sunset, Friday to Saturday.
Any barrels, or storage tanks or wine-making equipment must be kosher. There must be no contamination at all from non-kosher food products. No departure however minor is acceptable. This makes strict vegetarians very happy.
The exception to these rules is meshuval wine, that is, wine that is been pasteurized, or brought to boiling and cooled. Modern winemakers use flash pasteurization, bringing the wine to the boiling point within seconds and then "flash" cooling it down. Experts say this method doesn't adversely affect the wine at all.
I should point out that kosher for Passover involves a separate set of requirements, because of the necessity for purity. You can read more about kosher wine production here, here, and here.
Unfortunately, I have only been able to locate one kosher wine producing winery in Washington: Pomum Cellars winery in Woodinville. You can see a video review of two of their kosher wines, Pomum Cellars' 2005 Shya Red and Pomom Cellars' 2005 Syra. If you're still curios about kosher wine, I recommend the Kosher Wine Review, which includes lists by country of production as well as a list of meshuval wines (particularly useful in terms of catering, since the wine is still deemed kosher even if served by non Jews). Tree of Life Judaicia and Books in Seattle sells kosher wine, but none from Washington. I note that online purveyor Kosher Wine Online seems to offer kosher wine from every conceivable location except the Pacific Northwest, but I'm hoping . . .