There is an inside joke for those of us who work with the folks at the US Drought Monitor. If you want to make it rain (or snow), just put an area in D0 “abnormally dry” and the heavens will open up. That’s basically what happened this week – the rain and snow in Illinois reduced the concern of dry conditions across the state. As a result, the D0 in northern and western Illinois has been removed.
By the way, it is a lot easier to move in and out of “abnormally dry”. It becomes increasingly difficult to recover from drought as you increase the intensity and duration of the drought.
The US Drought Monitor introduced their D0 “abnormally dry” category across northern and western Illinois (first map). Should we be worried? We have been running about 2 to 4 inches below average on precipitation this winter (second map) – that’s both rainfall and the water content of any snow. The good news is that the demand for water is very low in winter. Therefore, the impacts on soil moisture, stream flows, and lake levels so far have been minimal.
The preliminary numbers are in and the statewide precipitation was 3.9 inches, 1.9 inches above average. Most of the state was in the 3 to 6 inch range except for some drier areas in central and western Illinois. It was wettest in southeastern Illinois with several sites with over 6 inches, including Smithland Lock and Dam on the Ohio River with 9.7 inches. By the way, the precipitation amount includes both rain events and the water equivalent of any snow.
Snowfall for January was below average and ranged from 6.5 inches in the northwest corner to zero in far southern Illinois (second map).
Even though January finished with below-average snowfall, it was offset with above-average rainfall in many areas. The impact of these rains were discussed in an earlier post. As a result, the U.S. Drought Monitor has reduced the area in drought or abnormally dry conditions since January 1 (last figure) by 11 percent.
The statewide temperature for January was 28.7 degrees, four degrees above average. It was far short of the warmest January on record that was established in 2006 with 37.9 degrees and followed closely by 1933 with 37.7 degrees. January precipitation (rain plus water content from snowfall). January Snowfall for Illinois. Change in the US Drought Monitor for Illinois through January 2013.
While the rains continue in northeastern Illinois, much of the rest of the state has been bone dry in August. Rainfall totals range from 3-5 inches in the Chicago area to less than an inch in many locations across central and southern Illinois. This band of dryness extends from southern Minnesota, eastern Iowa, Illinois, and into parts of Indiana and Kentucky (see first map).
Rainfall departures are on the order of 1-2 inches below average in the driest areas. Some of those same areas received little rainfall in July. The US Drought Monitor has much of central and southern Illinois in at least “moderately dry” with “moderate drought” in the central region of the state.
Of particular concern to me is that the few opportunities for substantial rain in August across central Illinois have resulted in only scattered showers/thunderstorms at best. There is another chance of rain on Tuesday/Wednesday but the projected amounts are on the order of 0.25 inches or less.
Update: USDA, National Ag Statistics Service (NASS) released the following on Illinois topsoil moisture (percent) by crop reporting district:
District
Very Short
Short
Northwest
4
21
Northeast
–
18
West
49
44
Central
31
38
East
40
44
West Southwest
26
58
East Southeast
13
46
Southwest
20
40
Southeast
30
56
State
25
41
Rainfall across the Midwest for August 1-22, 2011 (source: Midwestern Regional Climate Center). Click to enlarge. Rainfall departure from average in the Midwest for August 1-21, 2011 (source: Midwestern Regional Climate Center). Click to enlarge.
