Wind speed upper limit?
Posted: Tue 28 Oct 2014 1:06 am
I'm using Cumulus v1.9.4 with a Davis Vantage Vue 6250M + 6510SER (USA Metric model).
On the two previous occasions that we've had strong winds, Cumulus has measured exactly 140.0 km/h, in both cases from a roughly westerly direction. This is the maximum wind speed I've ever measured. On the first of those occasions there was no significant damage to houses in my area. On the second occasion there was significant damage to nearby houses (and a little to mine) - roofs blown off, for example.
I am suspicious because (a) two maximum readings (years apart) of exactly the same value seems a big coincidence, and (b) the substantial damage from the second occasion but not the first suggests the second wind was stronger than the first. The VV AWS is rated for wind speeds of 3 to 290 km/h, though in my area we don't generally expect anything much over 160 km/h.
I remember many years ago when I was using a Fine Offset AWS, there was a similar problem with the max speed being limited to some value (was it 98.5 km/h?) because Cumulus was reading only half of the station's speed register (or something like that). Steve fixed that in Cumulus, but I wonder if there's a similar subtle problem with the Vantage Vue data interpretation?
On both the abovementioned occasions, I didn't get to observe what the VV console was displaying, so I can't say for sure that there is a discrepancy between VV and Cumulus. Has anyone else noticed such a 'limiting' of maximum wind speeds?
On the two previous occasions that we've had strong winds, Cumulus has measured exactly 140.0 km/h, in both cases from a roughly westerly direction. This is the maximum wind speed I've ever measured. On the first of those occasions there was no significant damage to houses in my area. On the second occasion there was significant damage to nearby houses (and a little to mine) - roofs blown off, for example.
I am suspicious because (a) two maximum readings (years apart) of exactly the same value seems a big coincidence, and (b) the substantial damage from the second occasion but not the first suggests the second wind was stronger than the first. The VV AWS is rated for wind speeds of 3 to 290 km/h, though in my area we don't generally expect anything much over 160 km/h.
I remember many years ago when I was using a Fine Offset AWS, there was a similar problem with the max speed being limited to some value (was it 98.5 km/h?) because Cumulus was reading only half of the station's speed register (or something like that). Steve fixed that in Cumulus, but I wonder if there's a similar subtle problem with the Vantage Vue data interpretation?
On both the abovementioned occasions, I didn't get to observe what the VV console was displaying, so I can't say for sure that there is a discrepancy between VV and Cumulus. Has anyone else noticed such a 'limiting' of maximum wind speeds?
), so it might be awhile before I can check. But the fact that you've recorded 90mph suggests that 140kph is not an artificial limit.