Friday, September 20, 2013

2013's Precipitation In One Handy Chart

We're just about to hit the latter stretch of September, with October just a few short days away. With just over three months to go, it's pretty likely we're not going to set a rainfall record for the entire year despite our wettest summer on record* (asterisk to note that it was the wettest in Philly but not everywhere) this year.

I graphed out the year's 44 plus inches of rainfall to illustrate some important details.  First, a large chunk of this year's rain fell in two stretches through the summer.  19" of rain fell in eighteen days between early June (6.78" in eight days) and late July into early August (12.64").  43.7 percent of this year's rain fell in Philly in just those two stretches...

Chart of 2013's precipitation. Click to see full sized image.

Second, a reminder of how a three month window of soaking will change the reality of a year.  Through the end of May, Philly was running over four inches below average on rain (about 75 percent of normal year-to-point). The summer's 29 inches of rain effectively wiped out that deficit and will produce a surplus that would carry us through the balance of the year if it didn't rain a drop between now and the end of December.

The record for most precipitation in a year is 64.33", which is probably out of reach. Is a top 10 wettest year reachable? That's a different story. We're just shy of seven inches away from the tenth wettest year on record (1911). If we can coax "normal" between now and year's end, the top ten would be realized...and that would mark the third year in the last five that featured a top ten wettest year in the city.  2009, at 52.50", ranks sixth as of now.

The full list is on the left.