[wxqc] Wind Gusts

[Karl Uppiano]

There are various specifications (METAR, 
http://home.comcast.net/~dshelms/CWOP_Guide.pdf, etc.) that specify how 
these readings are taken.

For example, the default settings for the 1-Wire Weather Service for Java 
(http://mysite.verizon.net/Karl_Uppiano/wxservice.html) does the following:

o Current wind speed (including gusts) are recorded over 3 second intervals 
(i.e., averaged over 3 seconds)
o The peak gust is retained over a 2-minute sliding window, and reported to 
Weather Underground (in Rapid Fire mode) as the gust value, along with the 
current value.
o The maximum wind speed is retained for each reporting interval to the 
local log, APRS/CWOP and Weather Underground (in Standard mode) as the gust 
value, along with the average value over the last 10 minutes.

These parameters are all configurable, because different weather reporting 
specifications have slightly different requirements. The general strategy is 
usually the same, but the time constants can vary. Some of the more 
demanding "continuous real time" digital protocols present a problem because 
of the way that wind speed has to be calculated in the 1-Wire weather 
instrument. For example, it is possible to sample more frequently, for a 
more "instantaneous" current value, but the resolution is lower.

I don't know if this helps, but I thought a discussion of how other systems 
deal with wind measurement might be helpful.

Regards,
Karl

----- Original Message ----- 
From: "Mark Kimble" <mjkits at rit.edu>
To: "Discussion of weather data quality issues" 
<wxqc at lists.gladstonefamily.net>
Sent: Tuesday, June 10, 2008 10:44 AM
Subject: Re: [wxqc] Wind Gusts


>I had these questions as well.  It appears to be a matter of sample rate
> - of which the DVP doesn't take them fast enough to get the peak gusts
> all the time.
>
> -----Original Message-----
> From: wxqc-bounces at lists.gladstonefamily.net
> [mailto:wxqc-bounces at lists.gladstonefamily.net] On Behalf Of Victor
> Engel
> Sent: Tuesday, June 10, 2008 12:27 PM
> To: Discussion of weather data quality issues
> Subject: Re: [wxqc] Wind Gusts
>
> I think it depends upon the software. Where were you seeing the record
> of 23? Was it on the console, or was it in some software? If it was
> the console, what's indicated there is essentially instantaneous
> speed, although, technically, that's not even possible I guess, since
> the signal being sensed is a digital stream of pulses.
>
> Victor
>
> On Tue, Jun 10, 2008 at 8:41 AM, Lynnette Akiki
> <ljakiki at sylvaniaweather.com> wrote:
>> I'm still new to all this.  I received  Vantage Pro2 for Christmas
> last year
>> and installed the Anemometer at 33 feet.  We had a pretty nasty storm
> come
>> through last night.  My Vantage Pro2 only recorded a wind gust at
> 25mph and
>> that was long before the storm started.   During the storm I only
> clocked a
>> wind gust of 23. An OHDOT station less than 2 miles from me clocked at
> 48
>> mph.  By the way the tress were bending here it had to be at least
> that
>> here.
>>
>>
>>
>> How are wind gusts determined?  Does the gust have to be sustained for
> a
>> certain amount of time before it is recorded?
>>
>>
>>
>> Thanks in advance for your help.  I've learned a lot just by reading
> the
>> posts to this list
>>
>>
>>
>> Lynnette
>>
>>
>>
>>
>>
>>
>>
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