July in Illinois – Cool and Dry

The preliminary numbers are in and this July in Illinois was cool and dry. The statewide average temperature was 73.3 degrees, 2.0 degrees below the 1981-2010 average. It currently ranks as the 19th coolest July on record. Statewide records go back to 1895.

The statewide average precipitation was 2.74 inches, 1.31 inches below the 1981-2010 average. It currently ranks as the 29th driest July on record.

Despite the dry July, the statewide total precipitation for 2013 stands at 31.48 inches at end of July and 7.61 inches above the 1981-2010 average. It is the second wettest January-July. The wettest January-July was set just a few years ago; 2008 with 32.52 inches.

The rainfall in July was unevenly distributed across state. Much of central and northern Illinois were 1 to 3 inches below average while southern Illinois was several inches above average. See maps of accumulated precipitation and departures from average.

Mt. Vernon reported the highest monthly total in the state with 9.42 inches, followed closely by Olney with 9.15 inches. On the dry side, Joliet reported one of the lowest monthly totals with 0.63 inches along with 0.72 inches in Pontiac and 0.77 inches in Kankakee.

The wet spring and cool July have both helped to reduce the impacts of the dry weather so far but conditions will be watched closely in August.

Note: we had some technical difficulties so the maps are through July 30 instead of July 31. There was not much rain on the radar on July 31 so the maps are still fairly representative.

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July 2012 and 2013

What a difference in temperature between July 2012 and 2013. Last year we were in the midst of a full-blown drought and heat wave with temperatures routinely in the 90s and low 100s. The statewide average temperature for July 2012 was 81.8°F (6.5°F above the 1981-2010 average) and the second warmest July in Illinois behind the record of 83.1°F in 1936.

This July has had its hot and humid moments, but for the most part has been mild overall in Illinois. The statewide average temperature for July 2013, as of July 29, is 73.6°F ( 1.7°F below the 1981-2010 average) and the 23rd coolest July on record based on preliminary data.

The cool July weather was confined to the central and southeastern US. Meanwhile, both the western and northeastern US have experienced warmer than average temperatures this month.

Figures. July 2013 compared to July 2012 in terms of temperature departures from average.

Temperature Departures for this July through the 29th. Cool weather prevails across much of the lower Midwest.
Temperature Departures for this July through the 29th. Cool weather prevails across much of the lower Midwest.
July 2012 - toasty indeed.
July 2012 – toasty indeed.

Abnormally Dry Weather Creeps into Western Illinois

The latest US Drought Monitor has an area of “abnormally dry” conditions in western Illinois. This does not mean drought but it means that it is an “area of interest” to paraphrase what they say on TV when they have suspicions about someone but have no hard evidence.

In this particular case, the only evidence are widespread watering in towns and stressed corn and soybeans – especially the late planted fields with shallow root systems.

Rainfall amounts in those areas have been small and widely scattered (second figure). For example, Quincy airport has received only 0.25 since July 1. Combined with the high rates of evapotranspiration in July, roughly two-tenths of an inch per day, this situation can lead to the rapid withdrawal of topsoil moisture. Other areas in north-central Illinois may be candidates for the “abnormally dry” status in coming weeks if the rains do not return.

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July 2013 versus July 2012

I received the latest crop development report yesterday and was amazed by the contract from a year ago. The July 23, 2012, report noted that top soil moisture was 99 percent short to very short and 80% of that was in the very short category. Fast forward to the July 22, 2013, report and topsoil moisture was 27 percent short to very short only 2 percent of that was in the very short category.

Statewide Topsoil Moisture (USDA-Illinois)
Very Short Short Adequate Surplus
July 23, 2012 80 19 1
July 22, 2013 2 25 64 9

The US Drought Monitor looked a lot different between this year and last year in July (see figure below). Last year on July 24, 2012, all of Illinois was in some stage of drought and 71 percent was in the two worst stages. This year at about the same time – drought free.

We are watching conditions in western Illinois for developing dryness if they continue to miss the rains.

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Latest Outlooks from NOAA

NOAA Outlooks

Well, I guess no news is good news. While the latest monthly and seasonal outlook from NOAA (first figure) yesterday called for hotter conditions in the West and wetter conditions in the Southeast, we are stuck in the middle with EC – equal chances of above, below, and near-normal temperature and precipitation.

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U.S. Drought Monitor

The July 16, 2013, US Drought Monitor map for the Midwest – drought free in Illinois, Wisconsin, Michigan, Indiana, Ohio, and Kentucky. There are a few spots of “abnormally dry” in Missouri, Iowa, and Minnesota.

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