Fall Color

One of the best things about this time of year is the fall color. I suppose I’m hopelessly Midwestern because I even enjoy the change in color of the corn fields.
The question I often get is “How will the weather affect this year’s color?” It is hard to answer. Here are some comments I made in a press release a few years ago about the recipe for good fall color.

“Trees and shrubs need to go into the fall without a lot of stress from disease or severe drought. Chilly, not frigid nights and cool, sunny days enhance the changing leaf colors. Detrimental conditions include extended periods of rain or cloudiness that mute colors, high winds that blow leaves off trees, and hard freezes that stop color changes entirely… October and early November in Illinois should put on quite a show. Take some time to go out and enjoy it,” concludes Angel.

Check out the official site of the Illinois Office of Tourism for fall activities. The University of Illinois Extension Service site called “The Miracle of Fall” is an excellent source of information as well. [Update] NOAA has a featured story on fall color that includes a link to a more technical discussion of fall leaf color.
 

Miracle of Fall
University of Illinois Extension site on "The Miracle of Fall".

 

Tropical Storm Hermine Reaches Illinois

The remains of Tropical Storm Hermine have reached Illinois this morning. Rainfall amounts of 1 to 3 inches are possible and flash flood warnings have been issued. Check the National Weather Service as this event unfolds.
While we don’t often use the words “tropical” and “Illinois” in the same sentence, the remains of tropical storms and hurricanes have reached us before. Most of these systems came on shore in Texas and Louisiana and weakened considerably as they moved northward. Usually, the severe weather is gone by the time they reach Illinois but they can produce large amounts of rain than can lead to flooding.
The passage of four tropical systems alleviated drought impacts, particularly in southern and central Illinois during the 2005 growing season. The four systems were Tropical Storm Arlene, and Hurricanes Dennis, Katrina, and Rita. An article in the Illinois State Academy of Science by me described that situation in more detail.
More recently, in September 2008 the remains of Hurricanes Ike and Gustav produced heavy rains and flooding in Illinois. More on that particular situation can be found on my website.

Summer – One of the Warmest and Wettest on Record

Summer

This summer was one of the warmest and wettest in Illinois history, based on preliminary data. The average statewide temperature for this summer (June-August) was 76.4 degrees, 2.7 degrees above normal and the seventh warmest summer on record. The average statewide rainfall was 16.7 inches, 5.2 inches above normal and the sixth wettest summer on record. Statewide records for Illinois extend back to 1895.

August

The average statewide temperature for August was 76.8 degrees, 3.2 degrees above normal. That puts it at the 13th warmest August on record.  August was on track to being even warmer but a late-month cool spell knocked it down a few notches in the ranking. August rainfall has been close to normal with a statewide average of 3.4 inches, just 0.3 inches below normal.
[This is an update of a post earlier in August, now removed to avoid confusion]

Dry Weather in Southern and East-Central Illinois

After a wet start to the 2010 growing season, two areas of dryness have persisted in the last 60 days (see map below). The first area is far southern Illinois, where dry conditions extend back to June. The second, more recent area is in east-central Illinois. The hardest hit area appears to include parts of the following counties: McLean, Ford, Livingston, Iroquois, and Kankakee. Rainfall in that area has been between 25 and 75 percent of normal. Meanwhile, temperatures during that same period have run about 2.5 degrees above normal.
As expected, topsoil moisture in east-central Illinois has declined rapidly in recent weeks. According to the latest USDA NASS report, the “East” Crop Reporting District (CRD) in the heart of the dry area is showing that 35% of the fields sampled had “very short” and 48% of the fields had “short” topsoil moisture.
In southern Illinois, the percentages of fields with “very short” to “short” topsoil moisture are as follows:

  • East Southeast CRD: 16 % “very short” and 43% “short”
  • Southwest CRD: 17% “very short” and 65% “short”
  • Southeast CRD: 66% “very short” and 12% “short”
60-day rainfall departure
The 60-day (July 2 - August 30) rainfall departure from normal for the Midwest.

Cooling Degree Days Up in Illinois This Year

As of August 16, cooling degree days (CDD) are well above normal this year in Illinois. The statewide average is 1051 CDDs, which is 268 CDDs above normal or 134 percent of normal. Last year the statewide average through this date was only 640 CDDs.

Cooling Degree Day accumulations at selected cities.
City Accumulated Departure from Normal Percent of Normal
Chicago 961 +284 145%
Rockford 778 +175 129%
Moline 1028 +278 137%
Peoria 1044 +280 137%
Quincy 1123 +294 135%
Springfield 1214 +338 139%
St Louis 1583 +442 139%

Cooling degree days are calculated by subtracting the mean daily temperature by 65 degrees. Results above zero are accumulated over time. So if the mean temperature for the day was 75 degrees, then 75 – 65 = 10 cooling degree days. Accumulated over a season and compared to normal gives a relative idea of potential cooling costs. The higher the number, the higher the cooling costs.
Other factors that can influence cooling costs are humidity levels and solar radiation. Personally, I ran the A/C at home pretty much every day since mid-May. Last year I ran it for about two weeks the entire summer.

Maps for July 2010

Here are the thumbnail maps (click to enlarge) of July temperature departures, and July rainfall and rainfall departures. It was warmer than normal across much of eastern Corn Belt. It was much wetter than normal across much of the western Corn Belt.

July temperatures in the Midwest
July temperature departures from normal for the Midwest.

July rainfall in the Midwest.
July rainfall in the Midwest.

July rainfall departures for the Midwest.
July rainfall departures from normal for the Midwest.

July – Warmer and Wetter than Normal

The average temperature for July in Illinois was 77.7 degrees, 1.9 degrees above normal. That’s warm but not record-breaking by any means. By contrast, the average temperature of last July was 70.2 degrees. Not only was this year warmer but it was considerably more humid as well.
The average rainfall for July in Illinois was 5.6 inches, 1.8 inches above normal. BTW, the wettest July on record was 1958 with 8.03 inches.
The largest rainfall totals occurred in western and far northern Illinois as well as an area along I-70. Amounts of 8 to 12 inches were common in these areas.
Southern Illinois was much drier in July with amounts of only 1 to 3 inches in many locations. In fact, the US Drought Monitor categorized southern Illinois as being “abnormally dry” by. Another area of dryness is through central Illinois in an area bound by Moline, Kankakee, Danville, Springfield, and Peoria.

Warmer and Mostly Wetter July (so far)

The statewide average temperature for July 1-22, 2010, in Illinois is 77.2 degrees, 1.1 degrees above normal for this time period. The state average precipitation for the same period is 3.46 inches, 0.70 inches above normal.
Northern and eastern Illinois are a little drier on average. However, even those drier areas contain locations with very impressive rainfall amounts.

Midwest Rainfall
Midwestern rainfall for the period July 1-21, 2010. Map courtesy of NOAA's Midwestern Regional Climate Center.

Table 1. Temperature and precipitation amounts and departures from normal by climate division in Illinois for July 1-22, 2010. A map of the climate divisions can be seen below the table.

Climate Division Temperature (F) Depart (F) Rainfall (in) Depart (in)
Northwest 75.2 1.2 1.96 -0.86
Northeast 76.2 2.3 1.44 -1.41
West 76.9 0.4 6.54 3.58
Central 76.7 1.1 2.85 0.04
East 76.2 1.2 2.08 -0.88
South Southwest 77.5 0.4 5.05 -0.88
South Southeast 78.0 0.9 5.10 2.25
Southwest 79.3 1.0 2.89 0.39
Southeast 79.3 1.0 2.90 0.39
State 77.2 1.1 3.46 0.70
Illinois Climate Divisions
Illinois Climate Divisions (coincides with crop reporting districts as well).

June Rainfall Totals in Illinois

Here are the June 2010 rainfall totals for sites in Illinois, ranked from highest to lowest. The numbers are impressive with 35 sites scattered throughout northern and central Illinois reporting 10 or more inches of rain.
These numbers are preliminary and have not been quality-controlled. In some cases data may be missing that could lead to totals that are too low. Due to the localized nature of some of the heavier storms, one may see large differences over short distances. These sites are part of the NWS cooperative observer program – volunteers with standard equipment and observing practices.

June 2010 Rainfall Totals
Site Amount (in)
ST DAVID 13.75
BENTLEY 13.69
GALESBURG 13.24
VANDALIA 11.91
MOWEAQUA 2S 11.88
BRADFORD 3SSE 11.85
OGDEN 11.63
MILFORD 5 NW 11.61
PERRY 6 NW 11.57
ALTONA 11.56
STANFORD 2S 11.39
DAHINDA 11.31
KNOXVILLE 11.28
SHELBYVILLE DAM 11.19
FARMER CITY 3W 10.99
LINCOLN 10.80
CENTRAL ILLINOIS NWFO 10.79
HAVANA 10.58
PANA 10.52
CHICAGO MIDWAY AP 3 SW 10.50
SIDELL 5 NW 10.48
SPRINGFIELD #2 10.46
DECATUR 10.45
EARLVILLE 3 S 10.40
PRAIRIE CITY 2S 10.40
STREATOR 10.39
MARIETTA 10.36
SHERMAN 1 ESE 10.34
KANKAKEE METRO WWTP 10.22
CAMP GROVE 10.13
OAK BROOK 2W 10.09
ST ANNE 10.06
PLAINFIELD 3 NE 10.01
JACKSONVILLE 2 E 10.00
MORRIS 10.00
WINDSOR 9.94
BOURBONNAIS 3 NW 9.92
EFFINGHAM 9.92
LA GRANGE 9.78
MATTOON 9.78
KEWANEE 1 E 9.71
MARSEILLES LOCK 9.69
EFFINGHAM SE 9.66
HUTSONVILLE PWR PL 9.56
GRIGGSVILLE 9.50
CLINTON 1 SSW 9.48
DECATUR AP 9.36
RANTOUL 9.36
MENDOTA 2 SE 9.33
TAYLORVILLE 9.29
VIRGINIA 9.25
FISHER 9.24
OTTAWA 9.23
WHEATON 3 SE 9.19
JACKSONVILLE 2 9.14
BLOOMINGTON 5W 9.04
MARTINSVILLE 10S 9.03
ALEDO 9.01
HIDALGO 3SW 9.00
CHATSWORTH 8.94
SHABBONA 3S 8.90
PRINCEVILLE 2W 8.87
PARIS WTR WKS 8.82
CHAMPAIGN WILLARD AP 8.78
SPARLAND 6 SW 8.78
MT CARROLL 8.75
Moline Area 8.67
MOLINE QUAD CITY INTL AP 8.67
NEWARK 2 SSE 8.64
YORKVILLE 3 SW 8.41
NEOGA 4NW 8.40
CHARLESTON 8.38
KINCAID 8.38
PLANO 8.38
ATHENS 2SW 8.33
URBANA 8.33
ROMEOVILLE LEWIS UNIV AP 8.29
PERU 8.27
DANVILLE SEWAGE PLAN 8.26
LAKE SPRINGFIELD 8.26
PAW PAW 8.22
ATHENS 2 N 8.21
DWIGHT 8.20
WINCHESTER 8.20
WATSEKA 2 NW 8.19
Springfield Area 8.15
SPRINGFIELD CAPITAL AP 8.15
SULLIVAN 8.13
RAMSEY 8.09
ARTHUR 1W 8.08
PEORIA 5NW 8.05
LACON 1 N 7.92
ROSCOE 2 SE 7.76
CASEY 7.72
MACKINAW 7.70
NEWMAN 3W 7.70
CHICAGO MIDWAY AP 7.68
RANKIN 7.61
WHITE HALL 1 E 7.61
MONEE RSVR 7.48
MATTOON COLES CO AP 7.45
WOODSTOCK 5 NW 7.45
MT OLIVE 1 E 7.38
GLEN ELLYN 4 S 7.35
PARK FOREST 7.35
DANVILLE 7.28
NORMAL 4NE 7.21
PALESTINE 2W 7.19
QUINCY RGNL AP 7.19
HIGHLAND 7.11
MCHENRY STRATTON L&D 7.10
PAXTON 7.08
NEOGA 7.05
ELBURN 7.03
PITTSFIELD #2 7.02
ROANOKE 7.01
TUSCOLA 6.99
BEECHER CITY 6.97
SPRING GROVE 6.96
MORRISONVILLE 6.95
MARENGO 6.94
CONGERVILLE 2 NW 6.90
MUNDELEIN 4 WSW 6.89
CHANNAHON DRESDEN ISLAND 6.85
ROBINSON 6.84
MORTON 6.81
ST CHARLES 7 NW 6.78
NEWTON 6.70
EUREKA 6.62
HOOPESTON 1 NE 6.61
BEARDSTOWN 6.58
Peoria Area 6.54
PEORIA GTR PEORIA AP 6.54
DE KALB 6.53
AMBOY 6.52
FLORA 6.51
TRIMBLE 1E 6.49
ELIZABETH 6.42
WEST CHICAGO DUPAGE AP 6.42
BELVIDERE 6.39
CENTRALIA 6.28
JERSEYVILLE 2 SW 6.27
STEWARD 3S 6.21
ROCHELLE 6.19
Chicago Area 6.17
CHICAGO OHARE INTL AP 6.17
MONMOUTH 4 NW 6.16
BARRINGTON 3 SW 6.15
MINONK 6.13
Rockford Area 6.13
ROCKFORD GTR ROCKFORD AP 6.13
JOLIET BRANDON RD DM 6.09
LAWRENCEVILLE 6.06
NASHVILLE 1 E 5.86
NEW ATHENS 5.80
LOUISVILLE 5.75
SALEM 5.75
CHICAGO WAUKEGAN RGNL AP 5.74
CHICAGO BOTANICAL GARDEN 5.66
STREAMWOOD 5.59
HARVARD 5.57
LAWRENCEVILLE INTL AP 5.08
EDWARDSVILLE 2 W 5.02
KASKASKIA RIV NAV LO 4.97
CARLYLE RSVR 4.96
CHICAGO AURORA MUNI AP 4.94
CHENOA 4.81
OLNEY 2S 4.81
ALTON MELVIN PRICE 4.68
SMITHLAND L&D 4.66
MT VERNON 3 NE 4.63
BELLEVILLE SCOTT AFB 4.54
BLOOMINGTON WATRWRKS 4.52
ELGIN 4.21
BELLEVILLE SIU RSRCH 4.08
IUKA 3.83
GRAYVILLE 3.43
CARBONDALE SOUTHERN IL AP 3.34
GRAND CHAIN DAM 53 3.18
SHAWNEETOWN OLD TOWN 3.15
FAIRFIELD RADIO WFIW 3.11
CHICAGO PALWAUKEE AP 3.06
BROOKPORT DAM 52 2.73
CAHOKIA ST LOUIS AP 2.66

2nd Wettest June on Record

Illinois has experienced the 2nd wettest June on record, based on preliminary records through June 30. The statewide average rainfall was 7.8 inches, 3.7 inches above normal. The wettest June on record was 1902 with 8.37 inches. The rains over the weekend, especially north of I-80 and along I-70 caused this June to move up from fourth to second wettest June on record. Statewide records extend back to 1895. This number is provisional and may change slightly as more data comes in.
The larger rainfall totals occurred in the northern two-thirds of the state where amounts of 7 to 12 inches were common.  Meanwhile far southern Illinois remains closer to normal with amounts ranging from 3 to 6 inches.