US Drought Monitor for Illinois

The latest US Drought Monitor released today shows that the D3 “exceptional” drought has expanded in portions of northwestern Illinois.
The state of Illinois maintains a website on the activities of the Drought Response Task Force. In addition, the Illinois State Water Survey website has postings and archives of  information on the drought as it develops.

U.S. Drought Monitor for Illinois. Released August 9, 2012. Click to enlarge.

Long String of Warm, Dry Weather in Illinois

I have updated the plots of statewide monthly temperature and precipitation departures that start in January 2011 and include July 2012. We struggled with dry weather in 2011 but saw some recovery in November and December. However, every month in 2012 has been below normal. In addition, the last three months have shown increasingly larger departures with July being the worst.

Statewide monthly precipitation departures from normal for Illinois. Click to enlarge.

The statewide monthly temperature departures from January 2011 to July 2012 show that 2011 was a moderately warm year with 9 out of 12 months above normal. But the really warm weather (relative to the time of year) started in November 2011 and never really stopped through July of this year.
Statewide average temperature departures from normal for Illinois. Click to enlarge.

Rains Over the Last Week in Illinois – Good News for Some

Parts of Illinois received some welcome rains in the last week. The map below is a screenshot from a precipitation product provided by the Southern Region of the National Weather Service. This is based on high-resolution radar data, and corrected using the much sparser rain gauge network.
The areas in green received somewhere between an 1.0 to 2.5 inches, while the areas in tan or light yellow received over 3.0 inches. As a rule of thumb, we get about an inch of rain per week in August. So any area in green made small gains on the rainfall deficit for the season. Meanwhile those areas in blue received less than an inch and fall farther behind on the rainfall deficit for the season.
Locally, I got 0.68 inches at my house in Champaign over the weekend. In fact, I got more rain in the early morning hours of Sunday than in all of July.  My guess is that soybean farmers will be happy with anything we can get in August.

Seven day precipitation total ending August 6. Click to enlarge.

Tornado Drought

Tornado Drought in Illinois

One of the side effects of drought is that usually reduces the amount of severe weather we experience in Illinois. This year was a good example of this. After the deadly Harrisburg tornado on February 29, things have been relatively quiet. Here is the monthly breakdown of tornado reports in Illinois, as reported by the NOAA Storm Prediction Center:

  • 2 in January
  • 4 in February
  • 8 in March
  • 0 in April
  • 8 in May
  • 0 in June
  • 1 in July
  • 23 total by the end of July
Severe weather reports in Illinois for 2012 through the end of July. Figure courtesy of NOAA’s Storm Prediction Center.

Tornado Drought in the US

Harold Brooks of NOAA wrote about the US tornado drought on his blog. Here is the figure he used in his post for the US.

The number of tornadoes reported across the US from April 15 to July 31, for 2012 (red line at the bottom) as well for the most active year (2003) and the last widespread tornado-land drought (1988). Figure courtesy of NOAA.

No Surprise – July was Hot and Dry for Illinois

July was one of the hottest and driest on record. So was the year to date. Here are how things stack up so far.

How July Ranks

This July was the second warmest and fourth driest on record in Illinois, based on preliminary numbers for the month. The statewide average temperature was 81.8 degrees, 6.4 degrees above normal (1981-2010 average). The statewide average precipitation was 1.47 inches, 2.58 inches below normal or 36 percent of normal.
Statewide Average Temperature Rankings for July in Illinois

  1. 1936:  83.1 ºF
  2. 2012:  81.8 ºF 
  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:  1.47 inches 
  5. 1914:  1.51 inches

I think July 1936 still wins the prize as the most miserable month in Illinois records with the hottest temperatures and the third driest rainfall total. I’m sure 1916 was no fun either as the fifth warmest and second driest July on record. Of course, air-conditioning was pretty much non-existent in 1936. My dad says he remembers sleeping outside that July on the family farm in western Illinois (near Nebo) because the house was too hot.

How the Year-to-Date Ranks

This year so far is the warmest and third driest on record. The statewide average temperature for January-July 2012 was 56.9 degrees, 5.5 degrees above normal. The statewide average precipitation for January-July was 14.05 inches, 9.82 inches below normal or 59 percent of normal.
Statewide Average Temperature Rankings for January-July

  1. 2012:  56.9 ºF
  2. 1921:  56.1 ºF
  3. 1987:  54.1 ºF
  4. 1998:  54.0 ºF
  5. 2006:  53.9 ºF

Statewide Average Precipitation Rankings for January-July

  1. 1936:  12.22 inches
  2. 1934:  13.55 inches
  3. 2012:  14.05 inches
  4. 1988:  14.60 inches
  5. 1914:  15.20 inches

Rainfall Map

This rainfall map was generated by our GIS specialist Zoe and uses NWS radar and rain gauge data. The result is a more detailed picture of the rainfall in July 2012. A few lucky areas in northeastern and far southern Illinois received 2 to 4 inches of rain. Most of the state got an inch or less.

Image courtesy of the Midwestern Regional Climate Center. Click to enlarge.