Tuesday, October 21, 2008

Sea Breeze Express

Monday's forecast was for weakening trades to veer southeast with a chance for convection and sea breezes. You never know what you're going to get with a forecast like that - on or offshore, too strong or too light, clear skies or rain - you just have to watch it and hope it works for the site you have in mind. But it actually turned out to be good everywhere - all three of our windward sites were happily flown!

Dave flew Makapuu in a smooth strong easterly flow; visitors RT and Ian soared Lanikai, in what Ian described as angelic conditions; and I flew Kahana with the trusty Earls, Jeff and Jim. We had plans for a downrange mission together, but Jeff had to leave early for work and Jim arrived a bit late, so before it got too light I caught the last train to Pounders by myself. Thanks to Jim for the retrieve, and for sticking around to share a beverage.


firedave said...

Jorge was tandeming at Makapuu as well.

Anonymous said...

Dumb Question:
(regarding Sea Breeze Express)
What does 'a forcast of weakening trades to veer southeast with a chance for convection and sea breezes'mean?

Anonymous said...

(Same as above)
Raygan Woolsey (808-330-3858)

Alex said...

Hi Raygan,

Haven't heard from you in ages! Always good to know you're still alive and kicking. Maybe you can make it to Bob's house on Saturday Nov 1 for our party - it would be great to see you.

Tradewinds normally blow from the east, and 90 percent of the time they are a bit north of that, so let's say east-northeast. That's a perfect direction for our windward flying sites. But in the winter we have low pressure systems that come in and influence the trades to turn south of east, or kill them off completely for a while. If they still have any strength when they're coming from the southeast, we can fly Koko Crater in ridge lift for a change, but none of our windward sites will work. When the trades turn southeast but they're very light, or if they're suppressed completely to the point where we have no wind at all, a convective effect will produce breezes, which is just a fancy way of saying that the heating of the land produces air circulation. During the day the heat rises over the island and sucks the air onshore from every direction. That's a sea breeze - which is generally produces flyable conditions at a lot of our sites. During the evening the land cools and the air rushes back down and flows offshore. That's called a land breeze. Definitely not flyable, but since it's nighttime anyway, not a big deal.

Hope that answers your question - there's a good book that a lot of us used to read to try and understand flying weather - Dennis Pagen's Understanding the Sky. I could try to find my copy if you want to borrow it - let me know.

Brazilian Ray said...

If I may, I'd like to add one more fancy word (or two)... you probably heard of catabatic/anabatic winds... please check this short link:


At Maui's PoliPoli, it is common to experience catabatic winds early in the morning and launch on the first anabatic winds.