[wxqc] Rainfall Rate

[Dave Helms]

Victor,

I think the WD values you show are meant to be an a 1 hour rainfall 
forecast based on the most recent rate of fall measurement which is 
sampled over a very short period of time (10 seconds?).  

Dave
CW0351

Evan Bookbinder wrote:

> Sounds like a bug in Weather Display??? The Davis VP reports a 
> separate rainfall rate which would have numbers that you calculated in 
> the second listing. The second is the standard for rainfall rate, 
> which as you surmised, is different from hourly rainfall accumulation.
>  
> Evan
>  
>  
>
>     ----- Original Message -----
>     *From:* Victor Engel <mailto:brillig at gmail.com>
>     *To:* Discussion of weather data quality issues
>     <mailto:wxqc at lists.gladstonefamily.net>
>     *Sent:* Sunday, September 24, 2006 2:09 AM
>     *Subject:* [wxqc] Rainfall Rate
>
>     Today, my weather station had its first real storm. It measured
>     1.66 inches in 40 minutes. The rainfall amounts during the storm
>     went like this:
>
>     17:16 	0
>     17:21 	0.16
>     17:26 	0.43
>     17:30 	0.79
>     17:35 	1
>     17:41 	1.29
>     17:46 	1.53
>     17:50 	1.64
>     17:56 	1.66
>
>
>     where the second column shows the daily total.
>
>     Weather Display reported a rainfall rate matching these numbers. I
>     suppose that is accurate if the rainfall rate is meant to be an
>     average rate over the past hour. But obviously, if what we really
>     want to know is how hard it was raining while it was coming down,
>     then the rate should be the new accumulation divided by the
>     elapsed time. That gives the following chart:
>
>     17:16 	
>     17:21 	1.92
>     17:26 	3.24
>     17:30 	5.4
>     17:35 	2.52
>     17:41 	2.9
>     17:46 	2.88
>     17:50 	1.65
>     17:56 	0.2
>
>
>     This is more impressive. It also more accurately reflects how hard
>     it was raining at the time. Are either or both of these
>     calculation methods standards? Which is preferred?
>
>     Victor
>
>     P.S. The rest of town received anywhere from 0 to 1.44 inches,
>     with common amounts being under 0.1 inch. I didn't realize the
>     whole town wasn't unundated until the storm had passed and
>     internet access was restored so I could check around.
>
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