Does it rain more on the weekends?

When I first arrived in Norman, Oklahoma, for my postdoctoral fellowship in 1996, one of the first projects I started on my own was to see if it rained more on the weekend. In 1998, I published my preliminary results in the science humor journal, Annals of Improbable Research. (Link to that paper here.) Finishing up the formal publication of that paper took a lot more time and statistical prowess than I had. Eventually, the work was shelved in 2001.

Occasionally, I had received interest in this work. Maxim magazine even published a short interview with me on the topic for their Q&A section.

When I got to FMI, Ari Laaksonen and Doug Worsnop encouraged me to complete the research. Ari's graduate student Santtu was enlisted and off we went. We found no significant weekly cycles in precipitation at 222 stations across the United States, the most comprehensive assessment to date. Our work was published this month in Geophysical Research Letters.

Schultz, D. M., S. Mikkonen, A. Laaksonen, and M. B. Richman (2007), Weekly precipitation cycles? Lack of evidence from United States surface stations, Geophys. Res. Lett., 34, L22815, doi:10.1029/2007GL031889.

FMI made a press release that was picked up by the Helsinki Sanomat. Nature magazine, which wouldn't publish the paper, was happy to cite the work on their news site.

A recent paper in press by Bell et al. at Geophysical Research Letters claims to have discovered a weekly cycle, only in the summer in the southeast US, and only since the 1980s.

Looks like the fat lady hasn't sung yet on this topic...