[wxqc] Rainfall Rate

[Victor Engel]

WD simply reports the total amount of rain measured over the last hour. I
don't think it's particularly meant to be a forecast....

On 9/24/06, Dave Helms <dshelms at comcast.net> wrote:
>
> 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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