Here are the monthly temperature and precipitation departures from the long-term average by month in Illinois for 2013. After a warmer-than-average January, temperatures have been below-average in February, March, and April. Monthly precipitation has been above-average in January, February, and April, but slightly below-average in March.
This is a far cry from the first four months of 2012 which were noteworthy for being both above-average on temperatures and below-average on precipitation. See the second pair of figures for 2012.
More Rain on the Way in Illinois
Here is the latest Qualitative Precipitation Forecast (QPF) from the National Weather Service for the next three days. You can view maps for a variety of days on the NWS QPF page. The expected amounts for Illinois are sobering, ranging from just over an inch in northeast Illinois to over 4 inches (red) east of St. Louis.
April 4th Wettest On Record
Precipitation
This April was the 4th wettest on record for Illinois with 6.90 inches, based on the preliminary numbers. That was 3.13 inches above the long-term average of 3.77 inches.
To show you how wet it was, this April easily beat out the combined statewide rainfall totals for Illinois in May, June, and July of 2012 during the worst of the drought. The total rainfall for those months in 2012 were 2.50 inches, 1.80 inches, 1.48 inches, respectively, which led to a total of only 5.78 inches. That was 1.12 inches less than this April!
The first map below shows the spectacular rainfall totals across much of the state. The areas in yellow and orange were 6 to 9 inches. A few areas in pink and red were 9 to 11 inches. This product has a 4 kilometer resolution and is based on radar estimates calibrated with rain gauges.
The second map shows the same rainfall amounts expressed as a percentage of the long-term average. There was a small patch of below-average rainfall in far southern Illinois. Otherwise the rainfall across the rest of the state was much above average. Many areas in the dark blue were 2 to 3 times their long-average rainfall.
Speaking of rain gauges, the two largest monthly totals for April so far were Augusta with 12.28 inches and Naperville with 11.03 inches. Several more stations reported totals in the 10-inch range.
There were two major impacts of the wet April. One was widespread flooding on the Illinois, Wabash, and Mississippi Rivers and their tributaries. Several sites along the Illinois reported record high river crests in April. Because the flooding included the Chicago area, the dollar damages and number of people affected will be quite large.
The second impact of the wet April was the delay in fieldwork. In the April 29 USDA NASS report, only 1 percent of the corn crop was planted, compared to 76 percent last April, and a five-year average of 36 percent.
Temperature
The statewide average temperature was 50.1 degrees and 2.3 degrees below average. That was not record-setting but reflects the fact that we had a lot of cool, cloudy days in April.
Figures
