Received: from zonker.hpl.hp.com (zonker-fddi.hpl.hp.com) by opus.hpl.hp.com with ESMTP (1.37.109.18/15.5+ECS 3.3+HPL1.1) id AA289699307; Fri, 8 Aug 1997 15:28:27 -0700 Return-Path: <poulton@zonker.hpl.hp.com-DeleteThis> Received: (from poulton@localhost) by zonker.hpl.hp.com (8.7.1/8.7.1) id PAA19994 for wind_talk@opus.hpl.hp.com-DeleteThis; Fri, 8 Aug 1997 15:28:26 -0700 (PDT) Date: Fri, 8 Aug 1997 15:28:26 -0700 (PDT) From: Ken Poulton <poulton@zonker.hpl.hp.com-DeleteThis> Message-Id: <199708082228.PAA19994@zonker.hpl.hp.com-DeleteThis> To: wind_talk@opus.hpl.hp.com-DeleteThis Subject: Re: Pressure Gradient's? Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit
> It seems like wind prediction should be pretty straight forward.
> Wind will blow from areas of high pressure to low pressure.
Well, that's a start. But when I tried to build a numerical model of
winds at SFO from several years of data, I found that there are a lot of
things that are correlated to the wind we get, but even using them all,
I still got an error between model and actual values of around 5 knots
(standard deviation). This is about the same error that the NWS has
for its SFO forecasts.
Some things that we know matter:
- pressure gradient from ocean to coast
- pressure gradient from coast to the valley
- pressure gradient from the valley to the Great Basin (Nevada)
- jet stream direction and strength
- fog depth
- fog area coverage
- cloud coverage
- low pressure systems moving through
- corriolis effect on large areas of low/high pressure
- catabatic flow effect
- time of year
And even though we have all the above info, I, NWS and Mike Godsey all
totally missed calling Tuesday's big blow at 3rd.
Ken Poulton
poulton@opus.hpl.hp.com-DeleteThis
"Mother, the WEATHER is not a PRETTY THING." --Bill Griffith
"...forecasting is difficult, particularly with respect to the future."
-- Joel Bartlett, Ch 7 Weatherman
"Forecast for tonight: dark." -- George Carlin
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