As of 7/28/16, the statewide average precipitation was 6.73 inches. That ties 1915 as the third wettest July on record for Illinois.There are chances of rain over the last few days of July, but the amounts are not expected to be large. Therefore, the total may increase and break the tie for third, but is not likely to exceed the 7.61″ experienced in 1992 for second place.
Here is the top ten list of wettest Julys again:
Wow, the heavy rains just keep on coming in July. Last night it was central Illinois (left panel), and the day before that was northern Illinois (right panel). Click to enlarge maps.
It’s no surprise then that Illinois has had abundant rainfall in July as shown in the figure below with total rainfall (left panel) and departures from normal (right panel). Like the children of Lake Wobegon, all of Illinois is above average on rainfall (except for a few small pockets), as denoted by the shades of green and blue in the right panel.
Through yesterday, the statewide average rainfall was 6 inches, which is approximately double the normal rainfall for July thus far. It also puts us at number 8 at number 5 in the top ten list of the wettest Julys on record for Illinois with more rain on the way this week. It would be hard to beat the top two spots with the current NWS forecast, but moving all the way up to #3 is possible.
The Climate Prediction Center released their latest monthly and seasonal forecast today. We are still in between El Niño and La Niña. According to CPC, “La Niña is favored to develop during August – October 2016, with about a 55-60% chance of La Niña during the fall and winter 2016-17.”
For August, the southern half of Illinois has an increased chance of above-normal temperatures (top row in the figure). The northern half has “EC” or equal chance of above, below, or near-normal temperatures. Western Illinois is part of a larger area in the western Corn Belt with an increased chance of above-normal rainfall. The rest of Illinois is in the “EC” category.
The thunder is rumbling outside my window as I write this.Here is the radar/rain-gauge estimated rainfall for July (first map). Areas in green received only 1 to 2 inches, yellow 2 to 3 inches, oranges and reds 4 to 10 inches.
The second map shows these rains as a departure from normal for the first 18 days of July. There are several bands of above-normal rainfall across north-central and central Illinois. But the largest rainfall departures of plus 4 to 8 inches are in counties south of Carbondale.