After a very nice stretch of record-setting beautiful weather, things will start changing this evening and continue through the weekend. This will mean rain for tomorrow but a not so rainy day on Sunday. The surface analysis chart shows a number of weak low-pressure systems along the West Coast however with slightly higher pressure offshore this will keep the onshore flow in place. As a weak frontal system moves onshore tonight and into tomorrow this will allow a weak trough of low pressure to persist over the area through the weekend. All of these factors contribute to the fact that the models are not in agreement about what will actually happen on the racecourse.
April 23 500MB 
April 23 Surface Forecast 
April 24 Surface Forecast 
April 25 500MB 
April 25 Surface Forecast 
April 26 Surface Forecast 
April 27 500MB 
April 27 Surface Forecast
We do however know what will be happening with the tides which combined with what looks like a bit of light air will certainly make the racing interesting.
Tidal Currents in Admiralty Inlet off of Bush Point.
0706 Max Ebb 2.25 knots
1000 Slack
1254 Max Flood 2.33 knots
1624 Slack
1906 Max ebb 1.95 knots
2148 Slack
Sunday
0048 Max Flood 2.51 knots
0430 Slack
0742 Max Ebb 2.69 knots
1036 Slack
1336 Max Flood 2.70 knots
The surface forecast chart for tomorrow shows very little pressure gradient over the Pacific NW however with seven low-pressure systems, five inland from the Canadian Border south to the Sea of Cortez and two off of our coast, this will keep a southerly breeze over the central Sound for tomorrow morning. As the front moves through and dissipates this will bring, shall we say, unsettled conditions to the racecourse. Plenty of wind to get started however as the fleet goes north the wind will ease as you get closer to Pt. No Pt. By midday, a weak offshore flow will develop in the Straits resulting in a SE flow in Admiralty Inlet. With the tide starting to flood about 1000hrs this will keep the fleet on the beach and having to deal with the dilemma of Skunk Bay where there will be less tide but less wind. By mid-afternoon, the north end of Admiralty Inlet will be light and this will extend out to Protection Island. With max flood approaching three-knots at Pt. Wilson, this will make getting out to the Straits very interesting. Gradually, a weak onshore flow will develop in the Straits and slowly fill down Admiralty Inlet where eventually it will meet the southerly flow coming up the Central Sound. All the while, wind velocities will remain in the 5-9-knot range. This is going to keep navigators and tacticians on their toes trying to figure out where the next puff will come from. Once again the lighter boats with the taller rigs will do better in these conditions.
The current NAM model has the RP-55 around the course in about 15 hours finishing just after midnight, the TP-52’s around in 16 hours, the Beneteau 40.7 around in 19 hours, and the J-109 around in 19.5 hours, almost a sunrise finish.
On the short course, the J-105’s should be around in 8 hours finishing around 1800 hrs.
The other surface chart of interest is the 48hr surface forecast which sets a new record on the Roser Low Index Scale with 14 low pressure systems plotted, including the Post Tropical Cyclone Surigae making into the western Pacific. This will combine with another low-pressure system to produce a very strong low capable of hurricane-force winds in the western Pacific. We will definitely want to watch where this system goes especially since the 500MB charts show the flow becoming more meridional over the central Pacific.
Enjoy the weekend!
Ed. Note: For all of us small boat sailors, PSSR small boats promises to be shifty as well.
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)