Received: from zonker-fddi.hpl.hp.com by opus.hpl.hp.com with SMTP (1.37.109.8/15.5+ECS 3.3+HPL1.1) id AA12829; Tue, 29 Aug 1995 01:17:06 -0700 Return-Path: <poulton@zonker.hpl.hp.com-DeleteThis> Received: by zonker.hpl.hp.com (1.37.109.8/15.5+ECS 3.3+HPL1.1) id AA14344; Tue, 29 Aug 1995 01:16:55 -0700 Date: Tue, 29 Aug 1995 01:16:55 -0700 From: Ken Poulton <poulton@zonker.hpl.hp.com-DeleteThis> Message-Id: <9508290816.AA14344@zonker.hpl.hp.com-DeleteThis> To: wind_talk@opus.hpl.hp.com-DeleteThis Subject: Re: Wind predictors at 3rd?
> When you have time, would you please explain what you think are the best
> indicators of 3rd Avenue wind? Coyote wind? Sterling wind?
Winds near Coyote point typically are well correlated with SFO numbers.
This is not surprising, since Coyote is just 3 miles downwind from SFO.
The major gotcha is that there is a wind line caused by the southern
edge of the San Bruno gap which is near the shore at Coyote for the
typical direction of 290. Wind directions of 310 or more tend to bring
the wind all the way to the shore. Directions less than 290 will
decrease the wind at SFO somewhat, but they tend to move the wind line
way offshore at Coyote, making the wind line a mile or two offshore for
a direction of 270 or less. In these conditions, Coyote can be
practically becalmed.
I think winds at Crown Sterling tend to follow the same pattern, but
I don't sail there often enough to say for sure.
Winds in the channel at 3rd Ave are generally best correlated with the
SoSF_SBrMt readings. This is the same instrument as the 118.45 MHz
"shoreline departure" radio station, which is 800 feet up on San Bruno
Mountain. The major exceptions occur when stratus clouds ("fog") get
very close to the mountain - the readings get gusty as the clouds
approach and they can drop quite a bit if the clouds completely envelop
and pass San Bruno Mountain. You can tell when this happens because the
temperature gets down within a few degrees of the SFO dewpoint
temperature, usually about 55 F (the ocean temperature).
The direction at the San_Carlos station is useful for telling if the
wind is blowing over the highway 92 pass by San Mateo. When 92
is blowing, San_Carlos reads about 280; when it is not, San_Carlos
gets 330 to 020. This is about twice as much directional shift
as we see at 3rd under these conditions. The windspeed at San_Carlos
seems to be 3-10 knots less than at 3rd, so it is not very helpful.
I'm open to suggestions for Tigers, Candlestick, Crissy, Berkeley.
Ken Poulton
poulton@opus.hpl.hp.com-DeleteThis
"... one of the main causes of the fall of the Roman Empire was that,
lacking zero, they had no way to indicate successful termination of
their C programs." -- Robert Firth
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