"xmetman" wrote in message
...
On Monday, 8 February 2016 11:35:50 UTC, Norman Lynagh wrote:
On Mon, 8 Feb 2016 02:24:07 -0800 (PST), xmetman
wrote:
On Monday, 8 February 2016 09:21:57 UTC, Graham Easterling wrote:
On Monday, February 8, 2016 at 8:51:24 AM UTC, xmetman wrote:
On Monday, 8 February 2016 08:41:23 UTC, Graham Easterling wrote:
Gust of 86mph at Land's End. Mean speed reached 67mph!
Wind WNW offshore here, but still a gust of 59mph, the strongest in
a W-NW wind since November 2009.
Given the time of high tides, I think 6pm is a strange time to
remove the warning. Significant (not maximum!) swell height now
30' at Sevenstones. Easily the biggest since 2014.
Graham
Penzance
Graham
Where do you get that observation for Lands End from?
Bruce.
It's here http://www.landsendweather.info/met/mainframe.htm . It's
actually the Porthgwarra side of Land's End, near Gwennap Head. It's
run by John Chappell
I see from your list Culdrose reached 79mph. I think most of the the
west Penwith peninsula has seen gust well 70mph (ways from sheltered
Newlyn/Penzance). 76mph gust at St Ives.
Under these conditions the webcams are useless, covered in salt
http://magicseaweed.com/Live-Sennen-Webcam/65/ vut I hope to get to
Sennen this afternoon and hopefully post some pics lately.
I think the real flooding issues will be on this afternoons high tide,
the swell was smaller on the last one, and the period is getting longer
now.
Graham
Penzance
Graham
I can see the site and the anemometer and vane using Google street view.
Mean speeds as high as 67 and gust to 86 mph will cause damage and look a
tad high to me.
It got me to thinking about cup size of my Vantage Pro. I've just checked
mine and realised that I've had it on 'small' cups for many years
(oops!), I had thought it would default to 'large' (wrong!). I don't know
how much difference that will make to the speed, probably not a lot.
The upper air station at Camborne (81 M amsl) was meaning (at 09 UTC) 44
mph with gusts to 65 mph, that still can't match the latest live mean
wind speeds from Trebehor (270' ASL).
I suppose the Vantage Pro just collects 1 minute mean speeds and graphs
those values in its own LCD display, and it's down to the display
software on the PC to take the average of 10 of those one-minute values
to produce a 10 minute mean. A one minute mean of 67 mph would be
significantly higher than a 10 minute mean (~x1.2 or more higher). The
length of that mean should be a user setting I would have thought and I
bet it's not 10.
Bruce.
Bruce,
The Vantage Pro console receives a wind measurement from the anemometer
sensorevery 2.5 seconds. That is the ever-changing figure that is
displayed on
the console. It calculates a rolling 10-min mean from those figures which
can be
displayed in the text bar on the bottom of the console screen. There are
other
options for that text bar.
A random 1-min mean wind speed may be higher or lower than a corresponding
10-min mean within which it is embedded.
--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.
http://peakdistrictweather.org
Norman
Yes, of course you're right it could be. But what if the PC software people
use in conjunction with their AWS (to publish it on a website) has been
coded to select the highest 1 minute speed rather than the mean of the last
10 minutes?
All I'm trying to do is to compare like for like, i.e. mean wind speed
reported by people's AWS with those in UK SYNOPs, and it's not that easy!
Bruce.
========
In the real world it's gusts that do damage. And gusts can last for less
than a minute, so I'd say that peak 1 minute gusts will be most
representative of real life. Another issue is that we measure wind speeds at
10 metres above ground, so means speeds experienced by Joe Public will be
lower but 1 minute gusts will not be very different of course.
Will
--
" Some sects believe that the world was created 5000 years ago. Another sect
believes that it was created in 1910 "
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm
Will Hand (Haytor, Devon, 1017 feet asl)
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