Bad News for August in Illinois

The NOAA Climate Prediction Center has updated their forecast for August. It’s not good news for Illinois with an increased risk of above-normal temperatures and below-normal precipitation.

NOAA Climate Prediction Center temperature forecast for August, released July 31, 2012. Illinois has a higher risk of above-normal temperatures in August. Click to enlarge.
NOAA Climate Prediction Center precipitation forecast for August, released July 31, 2012. Illinois has a higher risk of below-normal precipitation in August. Click to enlarge.


Latest Analysis on the Impacts of Drought on U.S. Agriculture

The USDA has produced some interesting slides for the World Agricultural Outlook Board, showing the current drought overlaid on production areas. The first two are about the U.S. corn production areas, then the soybean areas, and finally the cattle areas. Each pair of slides shows a map of the overlay, and a time series of the area affected by drought.

By July 24, about 89 percent of the corn production area was in drought. That percentage has been climbing steadily since early June. It’s the same story with 88 percent of the soybean production area and 73 percent of the cattle production area in drought.

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Drought Intensifies in Illinois

The latest U.S. Drought Monitor has expanded D3 “extreme” drought across Illinois. It went from 8 percent of the state last week to 71 percent this week. This major shift was based on a number of short-term drought indicators based on rainfall, streamflow, and temperature, as well as from widespread reports of significant crop and pasture losses.

According to the USDA

The streamlined process provides for nearly an automatic designation for any county in which drought conditions, as reported in the U.S. Drought Monitor … when any portion of a county meets the D2 (Severe Drought) drought intensity value for eight consecutive weeks. A county that has a portion of its area in a drought intensity value of D3 (Extreme Drought) or higher at any time during the growing season also would be designated as a disaster area.

Earlier this week, the USDA NASS reported that 66 percent of the corn crop, 49 percent of the soybean crop, and 91 percent of pasture was rated poor to very poor. Topsoil was rated at 91 percent poor to very poor and subsoil was rated 97 percent poor to very poor. More details can be found in the weekly Illinois Weather and Crops report.

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Near Record Heat and Dryness in July

Based on data through yesterday, this July is shaping up to be one of the warmest and driest on record. Based on the forecast, this July is likely to remain as one of the warmest on record. My hope is that we get so much rain in the next week that we are not even close to the driest July on record.

Statewide Average Temperature Rankings for July in Illinois

  1. 1936:  83.1 ºF
  2. 2012:  81.8 ºF (as of July 30)
  3. 1901:  81.7 ºF
  4. 1934:  81.3 ºF
  5. 1916:  80.4 ºF

Statewide Average Rainfall Rankings for July in Illinois

  1. 1930:  1.02 inches
  2. 1916:  1.23 inches
  3. 1936:  1.24 inches
  4. 2012:  1.44 inches (as of July 30)
  5. 1914:  1.51 inches

Drought Expands in Illinois

The U.S. Drought Monitor released the latest drought map, showing that the “severe” D2 drought has expanded across much of northern Illinois. Only an area in the northeast part of the state remains in moderate drought (first figure).

The Climate Prediction Center also released their drought outlook today. They expect the drought in the central U.S. to persist over the next 3 months (second figure).

U.S. Drought Monitor map for Illinois, released on July 19, 2012. Click to enlarge.
Climate Prediction Center drought outlook, released on July 19, 2012. Click to enlarge.

Higher Risk of Hot, Dry Conditions for August and Fall

The Climate Prediction Center delivered more bad news for Illinois today. Their outlook for August includes an increased chance of above-normal temperatures across Illinois and much of the U.S. It includes an increased chance of below-normal precipitation for all of Illinois and much of the Midwest.

Their outlook for the 3-month period for August-October includes an increased chance of above-normal temperatures for Illinois and much of the eastern two-thirds of the U.S. and below-normal precipitation for Illinois and much of the Midwest.

NOAA Climate Prediction Center outlooks for August and August-October. Click to enlarge. 

Comparison of 2012 to 1988 in Illinois


The first figure shows the statewide precipitation departures by month for both 1988 (blue) and 2012 (red) in Illinois, using the 1981-2010 average as normal. There are several interesting features:

  • the period from January to March was actually drier in 2012 than 1988;
  • the 1988 drought started abruptly in April with dramatically less precipitation; April 2012 was dry but less so than February or March;
  • the precipitation departures in May and June of 1988 were slightly more severe (1/2 inch drier for each month) than 2012;
  • by the end of June, the precipitation deficit was 7.83 inches in 1988 and 7.25 inches in 2012;
  • while less severe than June, precipitation continued to be below normal from July to October in 1988; real relief did not arrive until November.

    Monthly precipitation departure in Illinois for 1988 (blue) and 2012 (red). Click to enlarge.


The next figure shows the statewide temperature departures by month for both 1988 (blue) and 2012 (red) in Illinois. There are several interesting features here as well:

  • temperatures from January to March in 2012 were much warmer than normal while they were much cooler than normal in 1988; in fact, January and February was significantly colder in 1988;
  • temperatures in April, May, and June were all above normal in 2012;
  • it wasn’t until May that temperatures in 1988 started to be warmer than normal;
  • warmer than normal temperatures continue in 1988 until October.
Monthly temperature departures in Illinois for 1988 (blue) and 2012 (red). Click to enlarge.


In summary, the 1988 drought started later than the 2012 drought, but once started it was more intense in the April-June period. However, temperatures were much warmer in 2012 than in 1988. In my opinion, those two factors balance out, making the the 1988 and 2012 very comparable at this point.

How is July unfolding? For the first 17 days of July, the precipitation amounts are identical between 1988 and 2012 at 0.8 inches (40% of normal for that period). However, temperatures for the first 17 days of July 1988 averaged 79.1 degrees, 3.3 degrees above normal. For this July, the average temperature was 82.3 degrees, 6.5 degrees above normal.