Re: Pressure Gradient's?

From: Ken Poulton (poulton@zonker.hpl.hp.com-DeleteThis)
Date: Fri Aug 08 1997 - 15:28:26 PDT


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Date: Fri, 8 Aug 1997 15:28:26 -0700 (PDT)
From: Ken Poulton <poulton@zonker.hpl.hp.com-DeleteThis>
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To: wind_talk@opus.hpl.hp.com-DeleteThis
Subject: Re: Pressure Gradient's?
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> 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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