Wind Direction + Wind Speed?

[acatalano]

I'm using CumulusMX on a PC with a DAVIS VP2. I have the Davis Display sitting next to the PC so I can keep an eye on things. Since installing Meteotemplates at boulderweather.org I've noticed a behavior that seems odd: When windspeed goes to zero, direction goes to North, at least in the Windrose block on my home page. I've looked at the data in the database, and the windrose does not seem to jibe with the data. The data actually goes to fractions of a mph, and in the rare instances that it goes to zero the direction does not seem to default to zero degrees. Likewise the Davis display on my desk, which shows the current direction and a number of recent directions in less bold arrows. This especially noticeable when it's dead calm; the Davis dispay will still show a series of non-North direction and the windrose will just show one big block pointed perfectly North. BTW I am using realtime.txt of course for the database.

So I'm wondering if the code for this has some fault in the calculation. It would seem prudent IMHO to keep the last direction in place when wind speed went to zero. I noticed the same behavior in the plug-in (gauges). Has anyone noticed this?

[Johnny]

Hi Anthony, I'm still using Cumulus One so this thought may not apply, but in Cumulus's Configuration/Station there is a tick box for 'Use bearing zero when calm'

Would this have any affect on your problem?

Cumulus Settings.JPG (21.9 KiB) Viewed 4242 times

[acatalano]

That might be the issue, although it seems the actual database data does not show that very well as there is little data that has zero speed. In fact I found it surprising that the wind speed data almost never went to an actual value of zero instead recorded fractions of a mph. Likewise my Davis display does not appear to deafault to North. But there is that selection possibility in CumulusMX. I'll check that out!