[wxqc] Rainfall Rate

[Evan Bookbinder]

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 
  To: Discussion of weather data quality issues 
  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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