Zambretti Forecast

[Snupple]

Hi, been fiddling with my Baro settings as my forecast is constantly saying 'Stormy, Much Precipitauion" all the time and reading the Zambretti forecasting description I noticed that it mentions that the forecast should be calculated at 9am.

Is it a possible to have a setting to do this?

[GraemeT]

You could use Beteljuice's Zambretti algorithm.

I use a php translation which can be run as a Windoze scheduled task.

The php is here:
http://weather.gktnet.com/public/weathe ... ti.php.txt

Beteljuice's javascript is available here:
http://www.dickie.webfusion.co.uk/zambr ... ecast.html

cheers.

[steve]

The 'stormy, much precipitation' message is nothing to do with the time of day that the Forecast is calculated. Does the full forecast include "Exceptional weather"? Are you sure you have your barometer extremes set correctly? See http://wiki.sandaysoft.com/a/FAQ#My_for ... itation.22

[Snupple]

Does the full forecast include "Exceptional weather"? Are you sure you have your barometer extremes set correctly?

No, it doesn't include exceptional and I've had the settings the same for a long time, but around xmas when it was damn hot and around 33-39C it would say that all the time.


I know its only for fun, just seemed way out this time...

ANYWAY, when I was doing some research I noticed that
http://www.whitbyweather.com/Zambretti/forecaster.html

says "A forecast made at approximately 09:00 local time is reportedly better than 90% accurate, "

but maybe I read it wrong and they are not saying thats the best time to use the formula and it is less accurate at different times of the day..

[GraemeT]

Yes, I read that also.
I think that it all gets down to who's got the clearest crystal ball...

As Steve says, setting barometer extremes is critical. If you set them wrong with Beteljuice's forecaster, the forecasts can be a mile off either way.
I've set cumulus to a few hPa above and below the max. and min. pressure over the last couple of years, but I'm still unclear on what are the best values to use.

[beteljuice]

I've set cumulus to a few hPa above and below the max. and min. pressure over the last couple of years, but I'm still unclear on what are the best values to use.

If the forecasts are (very) inaccurate, then that is the correct approach. (unless of course if some of them are regarded as extreme values - eg. typhoon etc.)

No, it doesn't include exceptional and I've had the settings the same for a long time, but around xmas when it was damn hot and around 33-39C it would say that all the time.

If that was exceptional then the forecast is correct, if it 'normal' for your location increase the top of the range a little.

Hi, been fiddling with my Baro settings as my forecast is constantly saying 'Stormy, Much Precipitauion" all the time and reading the Zambretti forecasting description I noticed that it mentions that the forecast should be calculated at 9am. ... Is it a possible to have a setting to do this?

Funny, it says that on my site as well
Actually it more correctly states "A forecast at approx. 09:00 local Solar Time is allegedly better than 90% accurate ! ".

I think there is already a setting somewhere to use 09:00 ish figures, but then you could lose some unexpected rapid change.

[wd40]

This is where Cumulus forecast shines. This is a small front moving fast. WU and TV forcast say no rain but Cumulus says:

[Matt.j5b]

With my station I am surprised that often it gets it roughly right because adjusting the pressure extremes helped but I don't alway keep an eye on that forecast.