Major May Coastal Storm

May 18, 2010

Still no change in models this evening, forecasting a highly unusual late May windstorm on the Coast.  15 to maybe as many as 20 millibars from the NW tip of Washington to North Bend, OR.  That’s a decent windstorm even in mid-winter!  Low level winds averaging 40-45 kts. hit the far north Oregon Coast and Washingotn Coast too.  That could even give gusts to 70 mph up in that area.  Isn’t summer around the corner?  Now the gradient up the Valleys from EUG to OLM gets up to around 10 millibars.  For the reasons noted below, I still feel it’s going to be a good late-May “wind advisory” event here in the Valleys.  South wind gusts of 30-40 mph should pop up for at least an hour or two sometime between 4-7pm.  Those speeds with all our decidous trees in full-leaf mode should give us at least a few power outages.  Not a big storm, but a talker as we say in the business by May standards!

Chief Meteorologist Mark Nelsen


Stormy May Weather Approaching

May 18, 2010

Quite a deep area of low pressure (for May) expected to develop and race northeast just off the Washington Coast tomorrow afternoon.  Models shows a 990-995 low with a nice bent-back occlusion bringing us gusty wind late tomorrow afternoon or early evening.  I’m really impressed by the wind forecast.  Our RPM model shows average windspeeds of 35-40 kts. running into the north Oregon Coast.   Definitely high-wind warning worthy with gusts 60+ mph likely.  That’s unusual for so late in the season.  I’ve included a graphic from our model at 6pm.  Along with the strong wind on the Coast you can see what effect land has on the windspeed too.  Much lighter here in the Valleys with average speeds 15-20 mph.  But then check out the next image.  Click for a larger view.   It’s the “forecast satellite image” for the same time.  The main band of rain/clouds has moved on by with plenty of sunbreaks in the late afternoon.  This is what has me thinking we could get strong gusty wind here in the Valley as well.  It’ll be a warm day…well-mixed airmass, we get sunbreaks behind the front, then the strongest south-north gradient up the valley develops (maybe 8 millibars EUG-OLM) at the same time the bent-back occlusion runs into Northwest Oregon.  That item shows up on the model product pretty well.  This leads me to believe we’ll get maximum mixing of strong wind up above down here to the surface.  So I think 20 mph wind with gusts 35-40 mph is quite possible right around the evening commute (4-7pm).  That’s real windy for May.  Our all-time highest wind gust in May is SW 48 mph at PDX.

Of course this leads us into a long period of cool and wet weather.  Thursday through Saturday should be very chilly and wet.  Possibly a break Sunday or Monday, then it’s on to more troughiness next week.  The ECMWF shows no hope for nice warm weather for all of next week either!

Chief Meteorologist Mark Nelsen