Assistant Indiana state climatologist Ken Scheeringa, located at Purdue University, has crunched the numbers. Indeed, through Jan. 21, last Friday, the winter of 2010-2011 is running behind both last winter and average on precipitation. It's also colder than last winter and than average- that part probably wasn't a surprise.
But it does help explain the precipitation trends, which may be a surprise to some. The colder the temperature, the more likely that precipitation will fall as snow instead of rain. Since it takes 10 to 15 inches of snow to get one inch of rain equivalent, there's less opportunity for liquid rain to fall if it's cold more of the time.
Weathermen think of the winter season as Dec. 1 through March 1, although the actual seasons according to the calendar run about three weeks behind. Based on Dec. 1 to Jan. 21, statewide Indiana has collected 62% of normal precipitation during this period this winter. In the winter of 2009-2010, the same comparison would have been 82% of normal.
This winter has averaged 4.8 degrees below normal, at 24.1 degrees. A variation that large on an average over an extended period is a definite trend in weather terms. One year ago, winter during the same period up until Jan. 21 averaged 1.9 degrees below normal.
Normal precipitation totals for Dec. 1 through Jan. 21 statewide would be 4.7 inches. At 2.27 inches water equivalent, the state on average is nearly 1.8 inches of water short through Jan. 21 this winter, compared to normal. One year ago it was less than an inch under normal.
Even northwest Indiana, with all of its snow, is still more than an inch behind normal on precipitation this winter, at 72% of normal. Last year at the same point the region was 82% of normal. The three southern crop reporting districts are most deficient, at 58, 56 and 58% of normal from west to east. One year ago, they were 80, 67 and 67% of normal.
Here's the bottom line. "Last winter, both to this point and for the entire winter, was somewhat cooler and drier than normal," Scheeringa says. "The winter of 2010-2011 to this point is colder and drier than even the winter of 2009-2010."