Wind Conditions

[Warriors Wish]

Would some of you old hands give me an idea as to what to expect for wind conditions in a typical transpac race. Thanks, Don

 

[tiger beetle]

Would some of you old hands give me an idea as to what to expect for wind conditions in a typical transpac race. Thanks, Don

Hi Don -

conditions on the course can vary considerably.

Generic race, a moderate strength Pacific High is stable and well formed off the California Coast, and there are no hurricanes forming in your path:

15-25 knot beat from the start, out the Golden Gate, to a point 15 miles offshore.

20-25 knots NW flow along the California coast, sail southwest for 500 miles to the ridge extending SE from the Pacific High towards Cabo San Lucas, Baja.

At the ridge winds will lighten considerably and swing aft, wind speeds 4-10 knots.

The next 1000 miles are downwind in the trades, 12-18 knots of wind to Hanalei. Nightly visits by squalls, wind speeds may bump 10-15 knots at the leading edge of the more powerful squalls.

Variations on the above theme:

Pacific High is solid and powerful, 25-40 knot NW winds off the California coast (gale conditions at start).

Pacific High is vacationing in the Aleutians or Hawaii and the inland Low drifts out to the California coast - 2-6 knot southerlies at the start, drifting light air conditions will persist for several days (until the High comes back).

Hurricanes tracking south of the fleet can cause the winds to go light up north, at least that's what happened to me one year. Also sailed into a total wall of zero wind mid-ocean in 2000 Pacific Cup race - turns out we'd hit the backside of a isobaric kink that three days later became a typhoon headed for Japan - fortunately it was way in front of us by then but kept leaving no wind behind it.

The Pacific High splits/fragments - now it is possible to sail over, thru, or under the goofy spread out High - you choose.

It's an El Nino year - trade winds go light.

At least those are some of what I've experienced. I'm certain there are many other experiences as well.

- rob

 

[sleddog]

With our current heatwave, a "southerly surge" is currently developing off S.CA, and making its way northward along the Coast. These "surges" are the bane of getting away from the Coast when racing to Hawaii, and occur several times/month during the summer, bringing a reversal of wind flow from the north to the south. A typical surge propagates northward and brings an onset of stratus and cool marine air. This coastal stratus and fog can be seen on satellite photos, and extends westward from the Coast out about 100 miles Surges typically last for 24-48 hours, at which time the wind reverts to more typical NW flow along the Coast.

As surges propagate northwards, they bring light to calm southerly winds, often meaning port tack outside the Gate. Such surges affect about 1 in 4 Races, including the starts of the '96 and '00 Pac Cups, and the '06 SHTP.

What is the best tactic for getting through a "surge?' Port tack takes you towards the Aleutians. And starboard aims you towards Las Vegas. I've always thought, when in doubt, sail the closest tack. Unfortunately, this has proven wrong as much as right.

Hopefully, the start of SHTP '06 will be into a building afternoon westerly seabreeze, and everyone will smoothly transition into the gradient NW winds that predominate outside the Farallones.

But, if a "Southerly Surge," enters the discussion, it requires initial patience and light air techniques.