Lake Winnipesaukee Ice-Out, Analyzing The 127 Years Of Data — To Celebrate Yesterday’s, i.e., April 17, Ice-Out For 2013.
by Anura Guruge
Yesterday was ice-out on Winnipesaukee.
Historic ice-out data going back to 1887 is available at winnipesaukee.com. So that is 127 years worth of ice-out dates.
I, for the first time this year, had a couple of hours off! I am waiting for Amazon to publish another Kindle book. So, I wanted to indulge myself while I waited (patiently) and given that I am strange crunching data is an indulgence.
So, I did some quick analysis. One thing I quickly noticed is that people don’t pay enough attention to LEAP YEARS. In terms of days into the year, March 23 & March 24 are both 82 days in — depending on whether it is a leap-year or not. So to say that last year was the earliest ice-out is wrong in a way.
I copied and pasted, did some concatenations and replaces, used (the now unsupported but still available) =DATEDIF Excel function and =WEEKDAY and voilà. [No, I never type in data.] Yes, I had to hand calculate the 13 pre-1900 years since Excel dates only start as of 1900 — but I used the Windows 7 calculator that can calculate dates going back to 1500 and one of my perpetual calendars. So, I ended up with a sortable Excel spreadsheet — which looked like this, after I had sorted it by data distribution. All calculations are based on days into the year, starting January 1 of each year.