Fine tuning Cumulus Forecast

[wd40]

I have been having been playing with the pressure extremes setting in the Cumulus forecast setting section. I have a few insights on fine tuning these setting or maybe I should say I have an opinion on how to set these numbers.

Steve has posted on several occasions that the forecast is for fun so it should not be taken anymore serious than that. To me, it is great fun just to see how close it can get.

From a micro stand point, your station generated forecast can, at times, be more accurate than a weather service forecast. I have seen post that suggest the Zambretti forecast is for 12 hours out but again from a micro view, the forecast is only viable for a time frame equal to the moving speed of a pressure area that makes your station report a pressure reading slightly different than the expected pressure in a weather service forecast. That, I would think, would limit the forecast to an hour or less or even down to a few minutes.

The high pressure setting is pretty straight forward. Just keep moving it up as your record high pressure changes. I leave it so the "Exceptional Weather" forecast gets triggered when that value is slightly exceeded.

The low pressure setting is a bit more tricky. Set too high and the forecast will say rain when there is none in the area. Set too low and there can be rain but forecast might say "good weather."

I wait for a small front to move my way. I un-check the hour forecast tick. Watch the forecast as a weak, rain generating front approaches and adjust the low pressure setting to get a matching forecast to the weather at your station. Keep checking and adjusting till you find a happy medium. A higher setting will produce a forecast with a greeter chance of rain. After the front passes, lower the setting in small increments if necessary so the forecast reflects improving weather conditions. This should yield a setting that is a good compromise.

I am no expert but I think this is a reasonable way to get a good setting for your area.

Randy

[nking]

An alternative way (or in addition to what you have described) is to consider amending the Forecast descriptions (in the Cumulus folder look for strings.ini) to better describe the weathers behaviour appropriate for your region.

[wd40]

A good point Neil. I did make a couple of small changes per
http://wiki.sandaysoft.com/a/Strings.ini

I added the list number just to give me an idea of where on the list the forecast came from.

forecast1=1Settled Good Weather
forecast2=2Good weather
forecast3=3Good Weather Coming
forecast4=4Good Weather but becoming less settled
forecast5=5Good Weather but possible showers
forecast6=6Fair Weather but improving
forecast7=7Fair Weather with possible showers early
forecast8=8Fair Weather showers may be in the area
forecast9=9Showers early but improving
forecast10=10Look for Better Weather
forecast11=11Fair Weather but showers likely
forecast12=12Rather unsettled clearing later
forecast13=13Unsettled, probably improving
forecast14=14Showers will come and go
forecast15=15Showers but storms possible
forecast16=16Rain possible
forecast17=17Weather Unsettled, but intervals of better weather
forecast18=18Unsettled, Rain Likely
forecast19=19Unsettled, a chance of rain
forecast20=20Good chance of Bad Weather
forecast21=21Rain with storms likely
forecast22=Rain at times, very unsettled
forecast23=Rain at frequent intervals
forecast24=Rain, very unsettled
forecast25=Stormy but may improve
forecast26=Stormy, Heavy Rain

[daj]

Code: Select all

forecast1=1Settled Good Weather
forecast2=2Good weather
forecast3=3Good Weather Coming
....

I think you should drop the number after the = sign

forecast2=2Good weather

Can't think why you need it

[Orion]

A Few More
forecast1=Settled Good Weather Off To The Pub
forecast16=Rain Possible Take a Brolly
forecast20=Good chance of Bad Weather Stay At Home And Watch A Good Film
forecast25=Stormy but may improve if your lucky
forecast26=Stormy, Heavy Rain Best Get The Boat Out

[wd40]

Can't think why you need it

No real good reason for sure.

I added the numbers just for curiosity sake. I was interested in how a forecast jumped around on the list. The number just makes it easier to do that.

Randy

[robynfali]

forecast26=Stormy, Heavy Rain Best Get The Boat Out

Been there, done that lol, 4ft of rain (and sewage ) through the centre of a town I used to live in!

[randerin]

I must be missing something. I see a file named samplestrings.ini

I changed the descriptions in that file, but it made no apparent differance. What am I doing wrong?

[steve]

I must be missing something. I see a file named samplestrings.ini

I changed the descriptions in that file, but it made no apparent differance. What am I doing wrong?

The samplestrings.ini file is a template from which you need to create a strings.ini file: http://wiki.sandaysoft.com/a/Strings.ini

[randerin]

Thanks! Works great. Looks like I am going to have to spend more time in the Wiki...

[wd40]

Thanks! Works great. Looks like I am going to have to spend more time in the Wiki...

Go through every section. Every time I do I find something new that I either missed or just forgot. Same with the "Help" section attached to Cumulus.

Randy

[elmdcw]

Hi,
I have a Davis VP2 and the forecast on the console is the same as displayed on the cumulus website:
http://www.weather.btinternet.co.uk/cumulus/
The realtime.txt file says that the forecast number is 2. But I can't find a list anywhere that matches the number 2 to the forecast as displayed on the device/website.
It's not forecast 2 as in strings.ini (or samplestrings.ini) or forecast 2 from the list of Davis forecasts as listed here: https://cumulus.hosiene.co.uk/viewtopic.php?f=6&t=4140
For example,
Cumulus console, Davis VP2 console and cumulus website all say "Increasing clouds with little temperature change. Precipitation possible within 24 to 48 hours".
This is forecast 44 (or very close to it from the linked Davis list).
Realtime.txt field 49 is 2.
Forecast 2 in strings.ini is "Fine weather".
The "Cumulus Forecast" box is not ticked.
So how do I match the forecast number to a Davis Forecast?
All help appreciated
Dave

[steve]

So how do I match the forecast number to a Davis Forecast?

Cumlus doesn't have access to any numbering system for the Davis forecasts, just the text. The forecast number in realtime.txt refers to the Cumulus ("Zambretti") forecast.

[ajcm]

hello:

1º) Cumulus have 1050-950 pressure extremes, and I have deselected the option "cumulus forecast" then forecast davis says: "Mostly clear with little temperature change" and if I select with extreme cumulus 1050-950 forecast says the same thing but if I select cumulus forecast and put in my area extremes 1035-985 now says: "Becoming fine", it is necessary to adjust the values ​​of extreme pressure in my area?

2°) Why when my area always arriving air warm desert of Africa with temperatures above 40 º C and low humidity below 15%, the Davis station and oregon always put icon of rain when it's really impossible to rain because the dry air reaches the 4000 meters and there are usually only cirrus.

3º) What is the formula used for the wind chill cumulus?
En el virtual weather station puedes elegir si quieres la nueva formula wind chill o no. Me han dicho que la formula es para zonas donde la temperatura es inferior a 6ºC y entonces en mi zona que la temperatura es superior a 13ºC el wind chill marca el mismo valor que la temperatura si uso la nueva formula, pero si deselecciono la nueva formula el wind chill baja la temepratura segun la velocidad del viento, en el caso de cumulus veo que no cambia la temperatura con el viento y la consola tampoco lo cambia.

According with manual of VWS:

6.18.6 New Wind Chill Calculation
On November 1, 2001, the National Weather Service (NWS) implemented a replacement Wind Chill Temperature (WCT) index for the 2001/2002 winter season. The reason for the change was to improve upon the current WCT Index used by the NWS and the Meteorological Services of Canada (MSC, the Canadian equivalent of the NWS), which was based on the 1945 Siple and Passel Index.

The new formula made use of advances in science, technology, and computer modeling to provide a more accurate, understandable, and useful for calculating the dangers from winter winds and freezing temperatures. In addition, clinical trials have been conducted and the results of those trials have been used to verify and improve the accuracy of the new formula.

Standardization of the WCT Index among the meteorological community is important, so that an accurate and consistent measure is provided and public safety is ensured. Our goal was to implement the new wind chill formula in Canada and the United States during the same time frame in order to have a consistent WCT Index for North America.

Specifically, the new WCT index will:

• use calculated wind speed at an average height of five feet (typical height of an adult human face) based on readings from the national standard height of 33 feet (typical height of an anemometer);

• be based on a human face model;

• incorporate modern heat transfer theory (heat loss from the body to its surroundings, during cold and breezy/windy days);

• lower the calm wind threshold to 3 mph;

• use a consistent standard for skin tissue resistance;

• assume no impact from the sun (i.e. clear night sky). Virtual Weather Station allows you to use the old or new
wind chill models. For more information, please reference the National Weather Service:

http://205.156.54.206/om/windchill/index.shtml

Thanks.

[steve]

3º) What is the formula used for the wind chill cumulus?

Cumulus uses the 'new North American' wind chill formula, as described here: http://en.wikipedia.org/wiki/Wind_chill ... hill_index

I can't answer any questions about the forecast and why/how it does/doesn't work.