Record-Setting April Rainfall in Illinois

Record-Setting Rainfall

[Updated May 2]

Based on preliminary data, the statewide average rainfall for April (as of May 2) is 7.59 inches, beating the old record of 7.13 inches set in 1957. Statewide records go back to 1895.

Rain, April 2011 (click to enlarge).
Rain, percent of average, for April 2011 (click to enlarge).

Selected Rainfall Totals

April rainfall has been heaviest in southern Illinois with several stations reporting over 10 inches of rain. Here are the rainfall totals through April 30 across the state, ranked from high to low. These are provisional and may change as more data comes in and as the data are processed through quality control at the national archive.

16.90 DU QUOIN 4 SE
15.29 BROOKPORT DAM 52
15.13 CAIRO 3 N
15.10 SMITHLAND L&D
15.04 MURPHYSBORO 2 SW
14.84 CARBONDALE SEWAGE PLT
13.94 CHESTER
13.92 GRAND CHAIN DAM 53
13.74 HUTSONVILLE PWR PL
13.68 CENTRALIA
13.31 OLNEY 2S
13.18 ROBINSON
12.97 SHAWNEETOWN OLD TOWN
12.56 LAWRENCEVILLE
12.53 MT VERNON 3 NE
12.40 PALESTINE 2W
12.15 MT CARMEL
11.92 KASKASKIA RIV NAV LO
11.91 PINCKNEYVILLE 2 N
11.87 CLAY CITY 6 SSE
11.87 CLAY CITY 6 SSE
11.78 CASEY
11.71 KINMUNDY
11.67 HIDALGO 3SW
11.66 MARTINSVILLE 10S
11.37 BEECHER CITY
11.12 EFFINGHAM SE
11.06 NEW ATHENS
11.04 FAIRFIELD RADIO WFIW
10.98 NEOGA
10.67 IUKA
10.54 EFFINGHAM
10.49 FLORA
10.47 SALEM
10.32 GRAYVILLE
10.29 PARIS WTR WKS
10.23 MATTOON
10.22 SULLIVAN
10.22 VANDALIA
10.19 RAMSEY
10.08 NASHVILLE 1 E
9.81 CHARLESTON
9.60 NEOGA 4NW
9.25 ST DAVID
9.07 FISHER
9.01 RANTOUL
9.01 GREENVILLE
9.00 SHELBYVILLE DAM
8.97 CARLYLE RSVR
8.73 WINDSOR
8.70 LEBANON
8.55 PRAIRIE DU ROCHER
8.49 HIGHLAND
8.40 TRIMBLE 1E
8.32 PANA
8.17 DANVILLE SEWAGE PLAN
8.02 TUSCOLA
7.94 EDWARDSVILLE 2 W
7.91 MT OLIVE 1 E
7.91 BELLEVILLE SIU RSRCH
7.87 TAYLORVILLE
7.81 ALTON MELVIN PRICE
7.72 DANVILLE
7.72 HOOPESTON 1 NE
7.66 PEORIA 5NW
7.59 ARTHUR 1W
7.50 GERMANTOWN HILLS
7.44 NEWMAN 3W
7.42 URBANA
7.38 PAXTON
7.35 BOURBONNAIS 3 NW
7.33 PEORIA GTR PEORIA AP
7.33 SIDELL 5 NW
7.32 ST ANNE
7.27 HAVANA
7.21 MOWEAQUA 2S
7.11 PHILO
7.10 DECATUR
7.08 LOVINGTON
7.02 OGDEN
6.95 MORRISONVILLE
6.94 MILFORD 5 NW
6.85 WATSEKA 2 NW
6.70 CLINTON 1 SSW
6.65 DAHINDA
6.52 SAYBROOK 2N
6.42 STREATOR
6.38 PARK FOREST
6.32 KINCAID
6.30 MARSEILLES LOCK
6.29 JERSEYVILLE 2 SW
6.27 CAMP GROVE
6.27 SHERMAN 1 ESE
6.24 CHANNAHON DRESDEN ISLAND
6.22 OTTAWA
6.19 DWIGHT
6.18 SPRINGFIELD #2
6.16 CHENOA
6.15 STANFORD 2S
6.08 PRINCEVILLE 2W
6.08 KEWANEE 1 E
6.04 BLOOMINGTON 5W
6.02 ROMEOVILLE LEWIS UNIV AP
6.02 PONTIAC
6.00 SPARLAND 6 SW
5.96 LANSING
5.95 LITTLE RED SCHOOL HSE
5.91 NEWARK 2 SSE
5.86 ELBURN
5.86 LA GRANGE
5.84 KNOXVILLE
5.83 FARMER CITY 3W
5.81 MASON CITY
5.73 CHICAGO MIDWAY AP 3 SW
5.73 ROANOKE
5.70 YORKVILLE 3 SW
5.65 ST CHARLES 7 NW
5.62 ELGIN
5.62 BRADFORD 3SSE
5.60 ELIZABETH
5.57 MUNDELEIN 4 WSW
5.55 MORTON
5.50 JOLIET BRANDON RD DM
5.49 NORMAL 4NE
5.49 NORMAL 4NE
5.46 SPRINGFIELD CAPITAL AP
5.45 PERU
5.45 PERU
5.45 MINONK
5.42 ALTONA
5.36 CARLINVILLE
5.35 EARLVILLE 3 S
5.35 MORRIS
5.33 CHICAGO BOTANICAL GARDEN
5.32 MENDOTA 2 SE
5.32 OAK BROOK 2W
5.32 JACKSONVILLE 2
5.31 SPRING GROVE
5.30 CHATSWORTH
5.30 WINCHESTER
5.28 EUREKA
5.25 PLAINFIELD 3 NE
5.22 LINCOLN
5.21 ALBERS 1 W
5.16 WOODSTOCK 5 NW
5.13 STREAMWOOD
5.08 BARRINGTON 3 SW
5.08 GLEN ELLYN 4 S
5.06 JACKSONVILLE 2 E
5.04 MOLINE QUAD CITY INTL AP
5.01 PRAIRIE CITY 2S
5.01 CONGERVILLE 2 NW
4.99 LAKE SPRINGFIELD
4.90 CHICAGO OHARE INTL AP
4.88 MCHENRY STRATTON L&D
4.87 VIRGINIA
4.80 MACKINAW
4.78 PITTSFIELD #2
4.78 CHICAGO MIDWAY AP
4.73 MORRISON
4.73 BLOOMINGTON WATRWRKS
4.68 BUFFALO
4.65 QUINCY DAM 21
4.63 WHITE HALL 1 E
4.57 RIPLEY
4.54 FAIRBURY WWTP
4.54 FREEPORT WWP
4.51 TOULON
4.44 AUGUSTA
4.41 DE KALB
4.35 MT PULASKI
4.35 GREENFIELD
4.34 HARVARD
4.33 ATHENS 2 N
4.30 STEWARD 3S
4.25 GENOA 2 SW
4.24 KANKAKEE METRO WWTP
4.21 CISCO
4.20 ROCHELLE
4.20 ROCHELLE
4.18 RUSHVILLE
4.16 ALEDO
4.14 GALESBURG
4.11 SHABBONA 3S
4.11 QUINCY RGNL AP
4.04 PERRY 6 NW
3.98 BELVIDERE
3.97 MONEE RSVR
3.94 BENTLEY
3.91 ROSCOE 2 SE
3.71 STOCKTON 3 NNE
3.66 BEARDSTOWN
3.65 AMBOY
3.62 PAW PAW
3.61 MT CARROLL
3.47 WHEATON 3 SE
3.45 MARENGO
3.40 ROCKFORD GTR ROCKFORD AP
3.20 GRIGGSVILLE
2.61 MONMOUTH 4 NW

Heavy Rains in Southern Illinois

Heavy rains fell across southern Illinois over the last week. Amounts of 4 to 8 inches were common in areas from Carbondale southward (see map). In addition, heavy rains fell in southern Missouri, southern Indiana, southern Ohio, and large portions of northern Kentucky. As a result, minor to major flooding was reported along the Mississippi and Ohio Rivers as well as many of their tributaries.

You can track current river observations and flood stage forecasts at NWS website:  http://water.weather.gov/ahps/

Heavy rains across the Ohio River Valley.

Severe Weather On April 19, 2011

Thunderstorms moved across Illinois on Tuesday, April 19, 2011, causing widespread damage from tornadoes, hail, and high winds. See map below. In Illinois alone, there were 15 reports of tornadoes – six in Macoupin County, six in Montgomery County, two in Christian County, and one in Vermilion County.

Hail amounts up to 2.75 inches in diameter were reported as well. The 2.75 inch hail fell in Roodhouse in Green County, followed closely in size by 2.5 inch hail in Golden Eagle in Calhoun County. A complete list of storm reports for April 19 is found at the Storm Prediction Center page for April 19.

The NWS is now conducting damage surveys:

[April 21: I added a map of SPC storm reports for the Midwest.]

Map of severe weather reports for the Midwest for April 19, 2011. The data are from the Storm Prediction Center and the map was created by Zoe Zaloudek.
NOAAs Storm Prediction Center reports on April 19, 2011.

First Half of April in Illinois – Warm

Based on preliminary numbers, the statewide average temperature for the first half of April is 54.0 degrees, 5.4 degrees above the 1971-2000 average.

The statewide average rainfall for the first half of April is 1.65 inches, 0.22 inches below average. Rainfall ranged from under an inch in far northern Illinois to over 2 inches in far southern Illinois (see map).

April rainfall
Rainfall for April 1-15, 2011, for Illinois.

Spring Frost in Illinois

Frost in spring is a concern to farmers, landscapers, and gardeners. Frost in Illinois is usually not measured directly at weather stations. Instead, it is inferred from the air temperature – when the air temperature crosses the threshold of 32°F.

The average date of the last spring occurrence of 32°F ranges from April 7 in far southwestern Illinois to April 28 in northern Illinois (see map below). The actual date can vary from year to year. The spring dates are getting earlier by about 5-10 days over the last few decades.

The actual date varies from year to year. For tender plants, add two weeks to the average date in the spring to protect against late season frost.

Although 32°F is the temperature traditionally used to show frost, visible frost can be seen on the ground and objects when temperatures are slightly above 32°F on calm, clear nights that allow cold, dense air to collect near the ground. Under these conditions, the temperature near the ground actually can be a few degrees cooler than at the 5-foot height of the official National Weather Service thermometer.

Open, grassy areas are usually the first to experience frost, while areas under trees are more protected because the trees help prevent the heat from escaping. Homeowners can protect tender plants by providing this same type of protection if they cover their plants when a frost is expected. Plants near heated buildings sometimes are spared too. Because of the abundance of warm buildings and trees in towns, they tend to experience frost less often than those living in the country.

Average dates of last spring frost in Illinois.

Tornado Tracks in Illinois 1950-2010

Using data from the NOAA Storm Prediction Center, our GIS specialist Zoe Zaloudek created a map of tornado tracks in Illinois from 1950 to 2010. The tracks are color-coded from blue to red to purple for F0 to F5 tornado events. The map below gives a general idea of the tracks, the PDF file is at higher resolution so that you can see much more detail.

There are some outstanding features. Like earlier studies, central Illinois is the most active region of the state. There are relatively few tornadoes reported in the northwest and southeast corners of the state. It could be the terrain – more hills and woods makes it harder to see tornadoes. Or it could be that those areas are also less densely populated.

Another feature is the local “hot spot” in Kankakee and Will Counties, relative to surrounding counties. We see a similar pattern with heavy rainfall events so it is probably genuine, and not an artifact of the data collection.

We have noticed a few artifacts in the map and are working with SPC to get those resolved. For example, there are a few instances of the tracks forming a triangle.

Illinois tornado tracks
Illinois tornado tracks from 1950 to 2010, using data from NOAA Storm Prediction Center. Map by Zoe Zaloudek, ISWS.

Soil Temperatures in Illinois

With the arrival of spring, Illinois farmers are monitoring soil temperatures for decisions in the field. And the soil temperatures are on the rise.

The ISWS Water and Atmospheric Resources Monitoring (WARM) Program records soil temperatures at 4 and 8 inches under grass at 19 sites across the state. In addition, 4-inch bare soil temperatures are computed to represent a cultivated field. These data are available in map and tabular form for the past 7 days at http://www.isws.illinois.edu/warm/soiltemp.asp.

As of April 6, the 4-inch soil temperatures under grass during the day are into the upper 40s in northern Illinois, the low to mid 50s in central Illinois, and the mid 50s in southern Illinois. At night they are cooling off by about 4 to 6 degrees.

The statewide soil temperatures give a general idea of conditions; however, soil temperatures in an individual field will depend on factors such as soil moisture and tillage practices. Also, soil temperatures at the surface will warm up and cool off faster than in deeper layers.