Yet another very interesting day for weather in the Pacific NW. It started with a tornado warning for the Central Coast this morning and then moments ago a special weather warning issued for a waterspout about 10-15 miles off the coast from Westport to Destruction Island. The combination of surface analysis, satellite pics, and Langley Hill Doppler radar all provide vivid confirmation of what’s happening out there.
The surface analysis chart shows a weakening low-pressure system and associated trough approaching the coast with a nice pressure gradient driving a southerly flow up the Sound. The breeze is still pre-frontal with a SE of 33 knots at Destruction Island. After this system moves to the east, a strong onshore flow will develop after midnight tonight and continue through Saturday. The offshore wind will change very quickly to a strong NW flow along the coast. While the wind in the Straits will remain at 15-30 knots from the west all day on Saturday, it will be light in the Central and South Sound until mid to late afternoon on Saturday when finally, the onshore flow will shift from NW to WNW and make it through the Chehalis Gap and into the South Sound.
March 19 500 MB 
March 19 Surface Analysis 
March 20 Surface Forecast 
March 21 500 MB 
March 21 Surface Forecast 
March 22 Surface Forecast 
March 23 500 MB 
March 23 Surface Forecast
It should also be noted that the NDBC sites are back up but not completely, data can be late or there can be gaps in the data. So, if you’re looking at the graphs of surface pressure and windspeed you’ll find some interesting plots.
While we have a nice breeze up and down the Sound today, when you look at the surface forecast chart for 20 March you’ll notice that the pressure gradient will ease considerably and this is what will bring lighter conditions for the Islands Race. The race will start with a light southerly up Colvos which will ease as the wind shifts from southerly to southwesterly. As the westerly in the Straits works its way down the Sound a convergence zone will develop from central Colvos north to Admiralty Inlet. This will dissipate by mid-afternoon as a westerly flow comes around the bottom of the Olympics.
Langley Hill Doppler 3/19 
NWS Forecast Office 
Satellite pic 3/19
After you round the top mark of the course there may be some residual southerly however once you get south of Blake Island you’ll want to favor the west side of Colvos in anticipation of puffs from the west and to stay out of the tide. Just don’t get too close to the beach on the west side as it will be light in there. As you get south in Colvos and the breeze becomes more westerly have the barber-hauler rigged and get ready for some aggressive trimming to take advantage of the close reaching conditions.
Another front will come through the area on Sunday and as you can see from the upper air charts, the jet stream will continue to bring wet and mild conditions into the Pacific NW. At least the jet steam is finally starting to move north so spring is on its way!
Happy Vernal Equinox!
Bruce has raced and cruised the Pacific Northwest his entire life. He earned a Bachelor’s of Science from the University of Washington in Biological Oceanography and learned meteorology “to keep from getting kicked around on the race course.” Bruce spent nearly two decades as Associate Publisher for Northwest Yachting Magazine, retiring in mid-2015, and was the chairman of the board of trustees for the Northwest Marine Trade Association in 2014. (photo of Bruce driving Playstation is a bit dated, but cool)