Bruce’s Briefs: Wx for 5, 6, 7, & 8 March. CYC Blakely Rock Race

Ed. Note – Bruce is going to give a chalk talk on the weather outlook for tomorrow’s Blakely Rock Race for CYC Seattle. See below for details.

As we said in November, it was going to be a wetter and cooler than normal winter and it has pretty much worked out that way. As of today, we are almost four inches of rainfall above average and even though last year was way above normal we are still .06 inches ahead of where we were a year ago. I bring this up because while we may have had some beautiful days this last week with above normal temps which got a lot of plants and trees starting to bloom, don’t expect more of the same this coming week.

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Today’s satellite pic certainly tells the story and when you combine this with the Surface Analysis chart and 500Mb chart you can see why we are going to have a very interesting weekend. The satellite pic shows the low-pressure system with the attached cold front off of our coast as well as the next frontal system. It’s the area behind the cold front (the comma-shaped solid white clouds) with all those irregularly shaped, puffy white clouds that will make tomorrow interesting for Blakely Rock racers. This marks an area of cooler, unstable air which will keep the post-frontal conditions unsettled. Think of it as pulses of breeze that will be coming through the Chehalis Gap and up the Sound. In the morning, since the breeze offshore will be very southerly this will keep the breeze in the Central Sound southerly. As the breeze offshore becomes more southwesterly, this will bring more of a southwesterly component to the breeze in the Central Sound. While this may seem straightforward, the problem will be that there can be areas of lighter air as these pulses of breeze move up the Sound.

As we get towards the late afternoon/early evening tomorrow, the breeze offshore will become more of a pre-frontal southeasterly in anticipation of the arrival of the next front (visible in the sat pic). This will have the effect of easing the breeze in the Central Sound until early Sunday. It will be the coast that will experience the higher winds and seas. This is where it also becomes useful to compare the surface analysis chart to the 500Mb chart. The surface chart shows three low-pressure systems moving in an almost circular pattern in the Gulf of Alaska down to our coast. The 500MB chart shows two upper-level lows off of BC with the jet stream coming ashore just north of San Francisco. Over the next four days, these two upper-level lows will consolidate into one and not move however this will have the effect of driving the jet stream further south which will keep us in a wet and cool pattern for the week.

As far as Blakely Rock goes, this should be a great race. Challenging but fairly consistent wind conditions and not much tide, however, as always, the geography of the Sound will have a profound effect on the breeze since we have to sail back and forth across the Sound.

Tidal Current at West Point

0948      Slack

1136       Max Ebb               .3 knots

1324       Slack

2000       Max Flood           .79 knots

The keys for the Race will be to get a clean start and sail into breakwater or Magnolia Bluff avoiding the outfall from the Ship Canal. Current radar has bands of rain moving across the area which will have the effect of slightly increasing the velocity of the outfall as well as increasing the ebb in the area of West Point because of the outfall from the Duwamish. The combination of rain plus a steady southerly will extend the ebb by about 20-30 minutes at West Point. There will be a slight SE shift from Shilshole to West Point inside of a line from Meadow Point to the Lighthouse. Just be careful not to get in too close to the beach as there may be a significant drop in windspeed. You will probably get to West Point on port tack and you’ll just want to hold port and sail across the Sound. As you cross, you’ll be slowly knocked. Watch your windspeed as you get closer to Bainbridge and while you may get a significant knock you may also lose wind speed.  You’ll want to work up to Blakely Rock favoring long starboard tacks and short port tacks. As always, be careful working south along Wing Point, it sticks out further than you may think. Plan your approach to Blakely Rock as it may be difficult to keep your air clear as the fleet will tend to compress at the rock. Watch the boats ahead to see what kind of sets they are doing.

It usually pays to do a port pole set at the mark as the breeze should be from the SW. This will hold until you are near Tyee Shoal where you maybe lifted so gybe out and sail your angles as you run north. Generally speaking, you will want to stay near the rhumbline or slightly to the west of rhumb and, of course, keep your air clear and anticipate overtaking situations. Give the slower boats a break and pass well to windward or way to leeward.

As you pass West Point, start planning your rounding at the top mark, which will hopefully be in the correct location. As you pass the start/finish line, check to see if one end is favored. You’d like to be the inside boat at the mark however that may mean a port gybe approach as the wind will probably be around to the SSW by then.

Once you round the top mark, it will be a long starboard tack back to the finish. Again keeping your air clear but working to the east. You’ll also want to watch the boats behind you in case a  big shift comes in from the west. If the boats astern are being significantly lifted out over you, bite the bullet and tack back out to the west to get into the new wind. Just don’t go so far that you overstand the finish.

If the boats astern aren’t lifted, check the boats ahead to see if there’s a SE shift on the beach going up to Meadow Point, then plan your approach to the finish.

Today’s models have the TP 52’s around the course in just about four hours. The J-35’s are around in about 5.5 hours.

Tonight CYC Shilshole is hosting a chalk talk where I’ll discuss the race as well as what the models from late this afternoon are showing. ( Ed. Note, sign up here!)

Have a great weekend and a great race.