Saturday, July 6, 2013

How Much Rain Have We Had


Let's Look At The Numbers For 2013:
The most popular questions that comes up when we receive a lot of rain is the following: "Michael, how much rain have we had?"

That is easily answerable since I do measure it daily. The follow-up questions ask if we have had more than normal.

The first chart is our average annual rainfall from the past 3 decade period beginning in 1981 and extending to 2009.

Month - Average 
Jan     5.07
Feb     4.89  
Mar     4.82 
Apr     4.53 
May     5.42 
Jun     4.64 
Jul     4.95 
Aug     3.83 
Sep     3.97 
Oct     3.23 
Nov     4.68 
Dec     5.65
Annual Average:  55.68             

The second chart is the rainfall by month this year.

Month - Actual 
Jan 6.35
Feb 2.35
Mar 6.44
Apr 7.09
May 5.24
Jun 5.46
Jul 5.41 thru 9:52 am on July 6th


OK...GREAT...WHAT DOES THIS TELL US?
Now,as many of you know, I like to go deeper behind those numbers. What do they mean?

Lets first answer the question on whether we've had more of not. Through July 6, our average annual rainfall would be 30.10". We have received 38.34" which is 8.24" more than normal and 27.4% increase. We're on pace to go over 70" for the year, which would put us at one of the wettest years in Cookeville's recorded history dating back to 1896. 70" of rain in Cookeville has only occurred six times in 117 years. 

A little more historical context. We measured 76.04" in 2009 (the second wettest year in Cookeville history behind the 76.46" total in 1998) after 4 straight very dry years from 2005-2008 where we received just 41.30", 45.32", 36.75" and 48.06". During that period, the average was just a little over 42". We're not that far off through only the first six months of this year.



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AMS

AMS
Member-American Meteorological Society