Dryness and Drought in Illinois, Illinois State Water Survey

Dryness and Drought in Illinois

llinois Drought Update - 8/30/2007top

Illinois State Water Survey, Department of Natural Resources

Precipitation deficits have increased across southern Illinois during August. The area has also been subject to very warm daytime temperatures, with maximum temperatures averaging above 95°F, or 8°F above normal. The combination of lack of precipitation and high temperatures has led to the intensification of drought to severe status as determined by the U.S. Drought Monitor. The impacts of the drought are agricultural currently, although continued dryness in the fall may lead to water resource impacts. The severe drought area in southern Illinois is on the northwestern edge of a much larger and more severe drought encompassing an area from the southern Ohio Valley to the Gulf of Mexico. Substantial temperature relief and scattered heavy precipitation occurred over the evening of August 29-30. The next five days are expected to be dry throughout and gradually warming, but there may be a return to a more active weather pattern with better chances of rain during the first week of September.

 

   View the Report   (pdf ~350k)

 

Report Contacts:

Jim Angel, State Climatologist - (217) 333-0729, jimangel@illinois.edu

Mike Palecki, Center for Atmospheric Science – (217) 333-8506, palecki@uiuc.edu

Ken Hlinka, Center for Groundwater Science - (217) 333-8431, khlinka@illinois.edu

WARM Program, Office of the Director - (217) 333-8431, jatkins@illinois.edu

Water Survey Web site: http://www.sws.uiuc.edu/hilites.asp


A Return to Typical Summer Conditions - 7/2/2007top

Illinois State Water Survey

A wet period across Illinois during June 22-29 has brought the State out of abnormally dry conditions, bringing a return to typical summer conditions.  In particular, up to 2 inches of rain or more fell in southern Illinois – the region of the State with the driest conditions – causing a rebound in soil moisture, streamflow, and groundwater levels. 

 

Like a typical summer, there remain smaller regions of Illinois where water levels are somewhat higher or lower than normal, reflecting varied rainfall patterns.  An overall precipitation deficit since March 1 in southern Illinois of 2-5 inches still remains; however there is no longer an extensive pattern of abnormal dryness.  Soil moisture conditions in the 0-72 inch layer are within 25% of normal in most locations (http://www.sws.uiuc.edu/warm/soilmoist/ISWSIllinoisSoilMoisture.pdf).  Streamflows are in the normal range (between the 30th and 70th percentiles) for most locations, although somewhat drier in southwestern Illinois (http://www.sws.uiuc.edu/hilites/dry/flowMap.asp?d=20070630). Groundwater levels are within the normal range for this time of year.

 

The five-day forecast by the National Weather Service predicts light to moderate rains across Illinois.  The Illinois State Water Survey will continue to monitor conditions, but does not plan to issue additional reports unless conditions change considerably. 

 

Public links to the maps showing rainfall for the last week and the rainfall departure since March 1.

http://www.sws.uiuc.edu/atmos/statecli/Summer2007/illinois-0702.gif
http://www.sws.uiuc.edu/atmos/statecli/Summer2007/illinois-mar-0702.gif

US Drought Monitor

http://drought.unl.edu/dm/monitor.html


Rainfall brings relief to Central Illinois – Southern Illinois remains dry - 6/25/2007top

Illinois State Water Survey

 

Two to four inches of rainfall in central Illinois within the last few days have brought most portions of this area out of abnormally dry conditions. Southern Illinois received considerably less rainfall and remains abnormally dry. Soil moisture and shallow groundwater levels in the southern part of the state have increased slightly in response to limited rainfall but continue their downward trend which is typical for this time of year. Dry conditions also are reflected in streamflow conditions which in parts of south-central Illinois currently are below the lowest tenth percentile.

 

The five-day forecast prediction by the National Weather Service indicates a potential of 1.5 to 2.5 inches of rain in the southern part of Illinois. They also predict the potential for about 0.5 to 1.5 inches in the northern and central portions of the state.

 

The Illinois State Water Survey will continue to monitor conditions and issue an update on Monday, July 2, 2007.

 

Public links to the maps showing rainfall for the last week and the rainfall departure since March 1.

 

http://www.sws.uiuc.edu/atmos/statecli/Summer2007/illinois-0625.gif

http://www.sws.uiuc.edu/atmos/statecli/Summer2007/illinois-mar-0625.gif

 

US Drought Monitor

http://drought.unl.edu/dm/monitor.html


Rain Brings Some Relief to Dryness in Northern and Central Illinois, but Conditions Remain Dry in Southern Illinois - 6/22/2007top

Illinois State Water Survey

 

Summary

Substantial rainfall amounts fell on June 21-22 in a broad band from northwestern Illinois to the Indiana border with several inches being recorded in the Quad Cities area. However, little rainfall was observed in southern Illinois. The U.S. Drought Monitor, updated on June 19, continues to indicate abnormally dry conditions for the southern two-thirds of Illinois, with moderate drought now indicated along the Wabash River. Near-surface soil moisture levels will see short-term recovery in areas that receive plentiful rainfall. No immediate changes have been noted at deeper soil levels. Streamflow levels continue to be low from southeastern into central Illinois. There are no new observations on shallow groundwater levels. Additional opportunities for significant precipitation are expected statewide over the next few days. An update will be issued by the Water Survey on Monday June 25.

 

Climate Conditions

Precipitation deficits have been widespread across Illinois since March and have reached levels in many areas sufficient to raise concerns about drought. This situation continues most apparent in southern Illinois. Total precipitation since March 1 is below average across the state, except for far northwestern Illinois: http://www.sws.uiuc.edu/atmos/statecli/Summer2007/midwest-mar-0622.gif, exceeding 6 inches in far southeastern Illinois. Rainfall for the month up to June 22 shows the recent beneficial precipitation:

http://www.sws.uiuc.edu/atmos/statecli/Summer2007/midwest-0622.gif

with general 0.5 to 1.5 inch totals. Localized totals exceeded 4 inches in northwestern Illinois.

 

The U.S. Drought Monitor of June 19 (http://drought.unl.edu/dm/monitor.html) indicates abnormally dry conditions for the southern two-thirds of Illinois and moderate drought creeping into the lower Wabash River Valley.

 

Streamflow

Stream levels for most of the southern half of Illinois have continued to slowly decline with little rebound following this week’s rains.  The region that is experiencing flows in the lowest 20th percentile for this time of year has expanded to now cover roughly 60 percent of the state.  Much of south-central Illinois is now classified as well below normal (in the lowest 10th percentile).  The Little Wabash and Embarras River watersheds in southeastern Illinois are experiencing the driest conditions with flows in the lowest 5th percentile. 

 

Soil Moisture and groundwater

In areas receiving rainfall, quick response is expected in soil moisture within the top few inches of the surface. Shallow groundwater levels will have a delayed reaction and will require more prolonged rainfall.

 

Outlook

Continued opportunities for precipitation are expected over the next few days as a frontal passage boundary moves through the state. Totals from 1 to 4 inches are forecasted, concentrated in west-central Illinois. Southern Illinois where conditions are the driest expects 1 to 2 inches.

 

Recommendation

While there are no critical situations for water supply, conservation measures are always a prudent course of action in case the developing dryness worsens. This situation will continue to be monitored very closely. An update of conditions will be provided on Monday, June 25.

 

Vern Knapp, 217 333 4423

Jim Angel, 217 333 0729

Al Wehrmann, 217 333 0493

Jennie Atkins, 217 333 4966


Crop Conditions - 6/19/2007top

The USDA weekly report on crop conditions reports that "Illinois weather last week was dominated by above normal temperatures and virtually no rain across the entire state." This site is updated each late Monday afternoon.
http://www.nass.usda.gov/weather/cpcurr/il-crop-weather

More information is available from their Illinois program office homepage. This area provides up-to-date statistics including all revisions:
http://www.nass.usda.gov/Statistics_by_State/Illinois/index.asp

Also available is an archive of weekly reports for this year:
http://www.agstats.state.il.us/Historical/2007historical.htm

Southern half of Illinois on the verge of drought - 6/18/2007top

Illinois State Water Survey, Illinois Department of Natural Resources

 

Summary

Precipitation deficits have developed statewide over the past few weeks and have reached levels in the southern half of Illinois sufficient to raise concerns that this area in particular may be on the verge of drought. The U.S. Drought Monitor is currently indicating abnormally dry conditions for much of Illinois. Near surface soil moisture levels have declined, although substantial soil moisture reserves remain in place at lower soil levels. Streamflow and shallow groundwater levels have fallen in response to the dryness, but levels are not yet extremely low in absolute terms. There is a chance of rain on June 18-19, but widespread heavy rain is not expected. This drying situation has developed rapidly and will be monitored closely in the next 2 weeks. An update will be issued by the Water Survey on Friday June 22.

 

Climate Conditions

Precipitation deficits have been widespread across Illinois in recent weeks and have reached levels in many areas sufficient to raise concerns about drought. This situation is most apparent in southern Illinois. In this region of the state, April and particularly May (http://www.sws.uiuc.edu/warm/iwcs/2007/may07.pdf) were drier than average. In the central and southeast, precipitation was less than 70% of normal. The first 18 days of June have seen an intensification of the dryness, again most notably in the central and southeast where less than 1/3 of the average precipitation has fallen. Total precipitation since April 1 is below average throughout the state (http://www.sws.uiuc.edu/atmos/statecli/Summer2007/april-present.gif). The largest deficits of more than 3 inches affected roughly the southern half of Illinois, except for the extreme southwest which was a little wetter. The effects of the dryness were exacerbated by very strong winds during June 6-8 and low humidity levels and minimal cloudiness throughout the first half of June that increased evaporation rates.

 

The U.S. Drought Monitor of June 12 (http://drought.unl.edu/dm/monitor.html) indicates abnormally dry conditions for the southern two-thirds of Illinois.

 

Soil Moisture

As a result of the deficient precipitation, soil moisture in the top 1 to 2 feet is below average in most areas. However, soil moisture in the top 6 feet is near or only slightly below average (http://www.sws.uiuc.edu/warm/soilmoist/ISWSIllinoisSoilMoisture.pdf) due to abundant precipitation in the fall and winter. This deeper source of moisture is yet to be tapped by agricultural crops.

 

Surface and groundwater

Streamflow has fallen to much below average levels for this time of year in southeast Illinois and below average in other areas (http://www.sws.uiuc.edu/hilites/dry/flowMap.asp?d=20070615). Above average levels are found only in extreme northern Illinois. Except for a relatively small portion of southeastern Illinois, the levels are not extremely low in absolute terms because levels are normally rather high in the late spring.

 

Shallow groundwater levels have begun to fall in response to the lack of rainfall and increased pumpage. Deeper aquifers are not being affected yet.

 

Impacts

Agricultural crops are being visually affected by the dryness in many areas of the central and south, but it is very early in the growing season and impossible to determine whether any yield potential has been lost.

 

Some municipalities are reporting an increased demand for water due primarily to lawn watering. Illinois American is reporting near record demand in its Champaign/Urbana service area and voluntary water conservation measures have been requested because of fears that the water treatment capacity may be outstripped. Several communities in the Chicago metropolitan area have restricted water use.

 

Outlook

A frontal passage during June 18-19 will bring some rain to the state. The heaviest rains are expected in the north. In the driest areas of the south, the rains are expected to be more scattered and lighter. This will be followed by several days of dry weather. The 6-10 day outlook (http://www.cpc.noaa.gov/products/predictions/610day/610prcp.new.gif) calls for below normal precipitation while the 8-14 day outlook (http://www.cpc.noaa.gov/products/predictions/814day/814prcp.new.gif) indicates near-normal precipitation. The seasonal outlook for June-August (http://www.cpc.noaa.gov/products/predictions/long_range/lead01/off_index.html) indicates equal chances for above and below normal precipitation.

 

Soil moisture reserves are available in lower soil layers for crop development if soil properties allow root penetration. Deep soils in central Illinois are likely to provide some buffer if dryness continues. However, the soils in southern Illinois tend to be shallower and the crops in those areas are more vulnerable.

 

Recommendations

Due to high water demand by crops and human activities, drought impacts can develop rapidly during the summer. The current situation is a prime example, where a 3-week period of little or no rain is beginning to have some impacts. This situation will be monitored very closely. While there are no critical situations for water supply, conservation measures are always a prudent course of action in case the developing dryness worsens.

Illinois Streamflows - 6/18/2007top

ILLINOIS STREAMFLOWS. Composite flow conditions for the first half of June are shown in Figure 1. Flow levels for much of the southern half of Illinois were below normal (below their 30th percentile). The watersheds of the Embarras, Little Wabash, and Kaskaskia Rivers, in particular, have experienced flows near or below their lowest 10th percentile for this time of year. If dry weather occurs in the latter half of June, the region of below-normal flows could expand to most regions south of I-80 and the region of flows in the lowest 10th percentile could easily double in size. We do not expect or know of any immediate surface water resource impacts from these low flow conditions. For most streams, the greatest potential impacts from a drought or dry period are often not experienced until late summer or early fall, the time of the year when flows are typically at their lowest condition. For current flow conditions, visit the USGS WaterWatch web site: http://water.usgs.gov/waterwatch.

 

WATER LEVELS AT PUBLIC WATER SUPPLY (PWS) RESERVOIRS. The most recent lake level reports for public water supply reservoirs are from the end of May. At that time, roughly half of the reservoirs in southern Illinois were below full pool, at a time of the year when pool levels are typically full and overflowing (levels in water supply reservoirs typically begin to drop below their normal pool in early July.) All of these water supply reservoirs were less than a foot below normal pool, except for Lake Paradise – one of two lakes that provide water for the City of Mattoon – which was 3.5 feet below normal. Lake Springfield was at full pool as recently as June 8, but by June 11 the City had already begun pumping water from the South Fork Sangamon River to supplement storage in the lake.

 

FEDERAL RESERVOIRS. With the dry conditions, Lake Shelbyville and Carlyle Lake may not complete their transition from spring to summer pool – as they remain 2.6 and 0.5 feet below their target summer levels, respectively. The dams are currently releasing relatively small amounts of flow, not substantially above their minimum flow releases, and lake levels are currently stable with little change during June. The level of Rend Lake has dropped 0.5 foot during the first half of June and is currently 1.5 feet above its primary spillway elevation – a level that is below normal for this time of year.

 

MISSISSIPPI, OHIO, AND WABASH RIVERS. The flows of the Mississippi River are in the normal range, being slightly below normal flows in the portion of the river upstream of its confluence with the Missouri River, and slightly above normal at St. Louis and farther south. Flows in the Ohio River are below normal, being in the lowest 20th percentile for this time of year. There are no reported impacts to navigation. The Wabash River is very low (lowest 10th percentile), as much of Indiana is experiencing dry conditions similar to southeastern Illinois.

 

ILLINOIS RIVER. The Illinois River is below normal for this time of year, but generally ranging in the 20-30th percentiles compared to the long-term average.

 

LAKE MICHIGAN. The water level for Lake Michigan has been at 577.7 feet during the first half of June, having risen 0.1 foot in the last month. The lake level is 0.2 foot lower than it was this time one year ago, 1.6 feet lower than its long-term June average, and 1.1 foot higher than the record June low that occurred in 1964. The levels in Lake Michigan typically rise throughout the first half of summer. However, Lake Superior is at near-record low conditions, and the reduced outflow from Lake Superior to Lakes Michigan and Huron may limit further increases this year in the Lake Michigan level.

Initial Release - 6/15/2007top

Conditions have been abnormally dry recently in central and southern Illinois. This term, abnormal dryness, refers to a lack of timely precipitation over one to several months that could lead to a drought forming if the lack of precipitation continues. The determination of drought status is dependent not only on the size of the precipitation deficit, but also on the initiation of impacts that can be discerned or anticipated. A change to the least intense category of drought, moderate drought, is declared by the US Drought Monitor when a combination of objective measurements coincide with reported impacts. In Illinois, agricultural impacts are most important at the time scale of the current abnormally dry period. The ISWS is closely monitoring the situation and will provide information to state government officials and the authors of the US Drought Monitor regarding the status of Illinois in the coming weeks.


For more information, please see the following:
   Drought in Illinois
   US Drought Monitor

Also See: Illinois Drought
| Highlights |


dry, dryness. dryer. dry. dryness, dry. dry. heat. and heat. hot. hot.

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