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Cumulus forecaster - wind speed and air pressure

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h2005__uk__
Posts: 5
Joined: Sun Jun 26, 2016 9:45 am
Weather Station: Fine Offset WH1080
Operating System: Windows 10
Location: Chelmsford

Cumulus forecaster - wind speed and air pressure

Postby h2005__uk__ » Sat Jan 07, 2017 11:54 pm

Hi

I've devised a forecasting tool for my Fine Offset station, based on the Zambretti forecaster. I've been reading this topic with interest - posting.php?mode=reply&f=11&t=2237

When the Cumulus forecaster considers whether the wind's 'dead calm' or not, is it average wind speeds that are considered or are gusts considered as well? I assume it's only a reading of 0.0 that's considered 'dead calm'?

In terms of air pressure, how far back does the forecaster look to decide what the trend is? What is considered to be rising/steady/falling? (E.g. more than 1.5mb could be rising.)

Thanks!

Peet
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Location: Heerhugowaard, Nederland

Re: Cumulus forecaster - wind speed and air pressure

Postby Peet » Sun Jan 08, 2017 11:17 am

I made a forecaster based on Sager and this uses pressure changes as follows:

> 1.4 rising rapidly
.7 to 1.4 rising
-.7 to .7 steady
-.7 to -1.4 falling
>-1.4 falling rapidly

Looking back one hour

h2005__uk__
Posts: 5
Joined: Sun Jun 26, 2016 9:45 am
Weather Station: Fine Offset WH1080
Operating System: Windows 10
Location: Chelmsford

Re: Cumulus forecaster - wind speed and air pressure

Postby h2005__uk__ » Mon Jan 09, 2017 6:14 am

Hi

Thanks for that - I wasn't aware of the Sager forecaster.

I note it uses cloud cover as part of its input - is this something that weather stations measure using a UV sensor?

A little off-topic, but my station doesn't measure cloud cover so I was wondering whether I could work it out by somehow using a script that checks the intensity of the cloud on a satellite image for my area... :idea:

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PaulMy
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Joined: Sun Sep 28, 2008 11:54 pm
Weather Station: Davis Vantage Pro 2 w/Envoy USB
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Location: Komoka, ON Canada
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Re: Cumulus forecaster - wind speed and air pressure

Postby PaulMy » Mon Jan 09, 2017 3:16 pm

Have you looked at viewtopic.php?f=14&t=9901&p=90706&hilit=btj#p90706
This uses the local METAR along with your station data.

I use it on my page http://www.komokaweather.com
Davis Station Forecast: Increasing clouds and warmer. Precipitation possible within 24 to 48 hours
Sager 12-24 Hour Forecast: Showers and warmer; No important change. Some tendency for slight increase in winds during day, diminishing in evening. South or Southwest winds.

Paul


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