I was recently given historical weather data for Washington, DC. The data are very interesting in a number of respects, but I noted something particularly odd about two days in August that are only three days apart: During the period of record, 1871-2010, rainfall on August 12th has exceeded rainfall on August 15th by a factor of 3.7 -- 40.95 inches vs. 11.12 inches. Further, the differences have been quite consistent over the years. For example, consider these figures for 30-year periods (20 years for the most recent data):
1871-1900: 9.07 inches total on the 12th, 3.73 inches on the 15th.
1901-1930: 11.90 inches total on the 12th, 0.85 inches on the 15th.
1931-1960: 12.22 inches total on the 12th, 4.31 inches on the 15th.
1961-1990: 2.16 inches total on the 12th, 1.60 inches on the 15th.
1991-2010: 5.60 inches total on the 12th, 0.63 inches on the 15th.
August 15th has never had more than 1.15 inches of precipitation, while August 12th has exceeded that amount nine times, and has exceeded two inches five times. In fact, two of the largest rainfalls in Washington, DC history occurred on the 12th -- 4.92 inches in 1898 and 5.44 inches in 1955.
Is this just a random variation, or is there something more to it? In searching for an explanation, I came across this article on-line -- http://www.atmos.was...eteors_1956.pdf. That article suggests that there could be a correlation between rainfall and meteor showers -- specifically that rainfall peaks may occur about 30 days after meteor showers. While this hypothesis would not seem to directly relate to the difference in rainfall between August 12th and August 15th in Washington, DC, I find it interesting that more than 55 years ago a meteorologist was suggesting a correlation between rainfall and meteor showers.
So, does anyone have any insight into this matter? For example, are there other areas where there are significant variations in rainfall on different days only a few days apart? If so, is there any evidence that meteor showers could play a role? Thanks.
