Active Weather Ahead

November 13, 2012

Finally, some weather action is on the horizon.  It’s been a very slow Fall weatherwise.  The first 40 days were bone dry with lots of sun; of course that’s nice when it’s still warm!  Then around October 11th the rains moved in.  We had some early season snow in the Cascades before Halloween.  Remember the base totals up around 20-30 inches?  The warmer rain around Halloween washed that away.  Now the first half of November has been real dead.  We can’t even get a gusty east wind out of the Gorge!  Probably no one complaining about that one though.

Now it appears we have a change towards a stormier westerly or southwest jet stream type pattern.  One in which we get numerous storms moving in from one of those two directions.

The 12z ECMWF and the 00z GFS are both very wet from Saturday through the middle of next week.   Both have more typical (for November) deep surface lows tracking near the Pacific Northwest coast at times.  This is a pattern in which we can get strong wind at the coastline and sometimes inland as well.  Something to keep an eye on.  Right now I don’t see anything that makes me think “WINDSTORM 2012!”

Once we get to Sunday and Monday, all eyes will be on the Cascades for two reasons; skiing and travel.  Next week is a big travel week of course with Thanksgiving right around the corner.  The 00z GFS came in quite warm later Monday and Tuesday as a cold upper trough briefly amplifies well offshore.  If so, 24 hours of heavy rain could delay ski area openings beyond a week from Friday (the day after Thanksgiving).  Otherwise, all other models seem to point to plenty of snow in the Cascades Saturday through next week.

Speaking of wind and windstorms, I’m giving my usual post-winter wrapup this Saturday at the AMS meeting at OMSI.  I just finished the presentation.   One of the slides is below.  What’s been missing here in western Oregon lately?  I still think we are overdue for a windstorm.  We haven’t seen a southerly gust above 53 mph in 12 years!!!  Now from about 1995 to 2006 ASOS anemometers (the instruments at airports) were using a 5 second gust, which meant a bit lower speeds than before and after that time.  For example, in the 1995 storm the ASOS measured 62 mph, but the old, shorter gust recorder at PDX recorded 74 mph.  For the purposes of this graph though, even sub-53mph speeds for 12 years seems like a long stretch.  Will this be the winter?  We’ll see.  The good news is that most likely we’ll see it coming days ahead of time; as with the 2006, 2000, and 1995 storms.  The only windstorm that has sneaked up on us in the past 20 years is the “South Valley Surprise” of 2002.

Chief Meteorologist Mark Nelsen