SEPTEMBER 2018 OVERVIEW

Transcription

1 September 2018 ILLINOIS WATER AND CLIMATE SUMMARY SEPTEMBER 2018 OVERVIEW Temperatures and precipitation were above the long-term average in Illinois in September. Mean streamflow statewide was well above the median for the month. Shallow groundwater levels were above the long-term depths. Air temperatures averaged 70.5 F in September, 4.3 above the long-term average (Figure 1). The southwest crop reporting district (CRD) had the highest temperature with an average of The lowest regional temperature was 67.3, reported by the northwestern CRD. Precipitation averaged 4.65 inches, 1.42 inches above the long-term average (Figure 1). The southeastern district was the wettest with an average of 7.67 inches. The driest was the west-southwest CRD with 2.40 inches. Soil moisture declined overall at depths from 2 to 8 inches. Levels at 20 inches and greater remained steady or showed slight increases. Mean provisional streamflow aggregated statewide was above the long-term median flow for September, about 500% of median (Figure 1). Monthly mean discharge values ranged from normal to much above normal for September. Unusually high seasonal flows were observed, particularly in northern and southeastern Illinois. Water surface levels at the end of September were below the full pool or target level at 18 of 26 reporting reservoirs. At the end of September, Lake Shelbyville was 0.3 feet above the seasonal target level, Carlyle Lake was 0.9 feet above the seasonal target level, and Rend Lake was 3.5 feet above the spillway level. Lake Michigan s mean level was above its long-term mean for the month. Shallow groundwater levels statewide were above normal this month with an average departure of 1.2 feet (Figure 1). An increase of 0.5 feet in departures was observed from the deviation in normal groundwater levels between August and September. Levels averaged 0.2 feet above August levels and were 1.2 feet above September levels of last year. Figure 1. Statewide departures from normal WATER AND ATMOSPHERIC RESOURCES MONITORING PROGRAM Contact Jennie R. Atkins (217) jatkins@illinois.edu

2 Weather/Climate Information Table 1. Temperature and Precipitation for September 2018 JIM ANGEL AND JENNIE ATKINS The following description of temperatures, growing Temp. ( F) Departure from longterm avg. ( ) Precip. (in) Departure from longterm avg. ( ) degree days, precipitation, severe weather, and drought comes from data compiled by a number of networks that report to the National Oceanic and Atmospheric Administration (NOAA). These data are provisional and may change slightly over time. September in Illinois was warmer and wetter than normal. Temperatures averaged 70.5 F, 4.3 higher than the month s long-term average (Table 1, Figure 2a). Illinois temperatures ranged widely from the high 90s to the low 30s. The month s highest reported temperature was 98, recorded on September 5 at the Bentley station in Hancock County. Mt Carroll in Carroll County had the lowest temperature, 30 reported on September 29. Growing degree days (base 50, from April 1) ranged from 2700 in northern Illinois to 7200 DDs in the south, DDs above the long-term averages (Figure 2b). Precipitation averaged 4.65 inches in September, 1.42 inches above the long-term average (Table 1, Figure 2a). The heaviest rainfall occurred in southern and northwestern Illinois where monthly totals of over 10 inches were reported. Both areas had heavy rain in the first half of the month as weather systems, including the remnants Illinois CRD 1 (northwest) CRD 2 (northeast) CRD 3 (west) CRD 4 (central) CRD 5 (east) CRD 6 (west southwest) CRD 7 (east southeast) CRD 8 (southwest) CRD 9 (southeast) Data from NOAA s National Centers for Environmental Information, accessed 10/9/2018. of Tropical Storm Gordon, moved through. The largest reported total was inches from a station near Clay City in Clay County. Drier conditions were seen in an area of the state stretching from St. Louis to Chicago where totals of 1 to 3 inches were common. The NOAA Storm Prediction Center had 40 severe weather reports for the month: 1 for hail, 2 for tornadoes, and 37 for wind. (Several reports can be generated for a single event.) Illinois was free of drought at the end of September. The September 25 U.S. Drought Monitor map listed 0% of the state as in drought and 3% as abnormally dry (Figure 4). AVERAGE TEMPERATURE ( F) ACCUMULATED PRECIPITATION (IN) Sept. 1, 2018 to Sept. 30, 2018 Departure from average Sept. 1, 2018 to Sept. 30, 2018 Departure from average Figure 2a. Illinois temperature, precipitation, and their departures from average for September 2018 Source: cli-mate, Midwestern Regional Climate Center. accessed on October 1, PAGE 2

3 TOTAL MGDD FROM 4/1/2018 TO 9/30/ ACCUMULATED PRECIPITATION (IN) Jan. 1, 2018 to Sept. 30, 2018 Departure from average Apr. 1, 2018 to Sept. 30, 2018 Departure from average July 1, 2018 to Sept. 30, 2018 Departure from average 4200 MGDD DEPARTURE FROM 4/1/2018 TO 9/30/ Figure 2b. Illinois growing degree days and departure from average through the end of September 2018 Source: Midwestern Regional Climate Center. accessed on Oct. 1, Figure 3. Illinois precipitation and precipitation departure from average for year to date (top), last 6 months (middle), and last 3 months (bottom) Source: cli-mate, Midwestern Regional Climate Center. accessed on Oct. 1, PAG E 3

4 U.S. Drought Monitor Illinois U.S. Drought Monitor Illinois September 25, 2018 (Released Thursday, Sep. 27, 2018) September 25, 2018 (Released Thursday, Sep. 27, 2018) Valid 8 a.m. EDT None D0 D1 D2 D3 D4 Illinois Climate Network (ICN) September 25, 2018 JENNIE Last Week ATKINS (Released Thursday, Sep , 2018) Valid 8 a.m. EDT Drought Conditions (Percent Area) Current Months Ago The Illinois Climate Network (ICN) consists of Drought Conditions (Percent Area) Calendar Year None D D1 D2 D3 D4 19 stations across the state that collect hourly Water Year One Year Ago weather and soil information. ICN data for Intensity: September are presented in Table 2. Valid 8 a.m. EDT D2 Severe Drought Wind speeds were Calendar Year The Drought Monitor focuses on broad-scale conditions. slightly Local conditions higher may than vary. See accompanying in text summary for forecast statements. Water Year 7.40 August, averaging mph Author: Drought Conditions (Percent Area) One Year Ago or 0.2 mph lower than the Jessica Blunden September 25, 2018 long-term NCEI/NOAA average. ICN None D0 D1 D2 D3 D4 (Released Thursday, Sep. 27, 2018) Intensity: Stelle had the month s D0 Abnormally Dry highest D3 station Extreme Drought Valid 8 a.m. EDT average at Current D1 Moderate Drought D4 Exceptional Drought 7.8 mph and the highest Drought Conditions (Percent Area) D2 Severe Drought recorded wind gust with The Drought Monitor focuses on broad-scale conditions. Last Week None D Drought D D2 Conditions D D4 (Percent Area) Local conditions may vary See accompanying mph on text September summary for forecast statements None D0 D1 D2 D3 D4 25. Current Author: Air temperatures 3 Months Ago Jessica 0.00Blunden averaged 69.9 across the Last Week Current NCEI/NOAA network, 4.5 higher than the network average. 3 Months Calendar Ago Last Week Year Temperatures showed a general cooling trend Calendar 3 Year Water Months Year Ago over the month as network daily averages declined from Water YearStart 7.40 of One the low 80s to the mid-60s. Calendar Year Year Ago However, even at the end of One Year Ago September, daily highs were in Intensity: Water Year the mid-80s. The network s highest Intensity: temperature was 99.7, recorded at D0 Abnormally Dry D3 Extreme Drought D0 One Abnormally Year Ago Dry ICN Stelle on September 3. The lowest was 34.3, measured D3 Extreme Drought at the DeKalb station on September 29. D1 Moderate D1 Moderate Drought Drought D4 Exceptional Drought D4 Exceptional Drought Soil temperatures decreased 3 5 from August to D2 Severe Intensity: D2 Drought Severe Drought averages in the mid-70s. Temperatures were 3 to 4 above The Drought Monitor focuses on broad-scale conditions. The Drought D0 Abnormally Monitor focuses Dry on broad-scale D3 Extreme conditions. Drought the long-term averages. Under bare soil, temperatures Local conditions may vary. See accompanying text summary for forecast Local statements. conditions may vary. See accompanying text summary ranged from 45.6 to at depths of 2 inches and 47.4 for forecast D1 Moderate statements. Drought D4 Exceptional Drought to 97.8 at 4 inches. Temperatures under sod ranged from Author: D2 Severe Drought 57.2 to 93.9 at 4 inches and 58.8 to 89.1 at 8 inches. Jessica Precipitation was higher than normal for most ICN Author: The Blunden Drought Monitor focuses on broad-scale conditions. NCEI/NOAA Local conditions may vary. See accompanying text summary stations in September with an average of 5.58 inches or Jessica for forecast Blunden statements inches higher than the network s long-term average. NCEI/NOAA A large portion of the month s rainfall occurred during the first eight days as weather systems such as the remnants of Tropical Storm Gordon passed through parts of the state. The highest totals were in the south where ICN Rend Lake reported inches, the highest for the month. In comparison, the Stelle station recorded 2.19 inches, the Figure 4. U.S. Drought Monitor report for Illinois Source: U.S. Drought Monitor. Author: Jessica Blunden, NCEI/NOAA. accessed on Sept. 27, month s lowest total. Soil moisture declined overall in September (Figure 5). Moisture levels peaked on September 8 and showed a general decline for the rest of the month. Soil moisture declined 10%, on average, at depths of 2 inches. Levels Current Last Week Months Ago D0 Abnormally Dry D1 Moderate Drought D3 Extreme Drought D4 Exceptional Drought PAGE 4

5 increased during the month only at the southern stations. Declines also occurred at 4 and 8 inches. However, at depths of 20 inches and greater, soil moisture remained steady over the month or showed slight increases. Table 2. Data from the Illinois Climate Network (ICN), September 2018 Wind Air Temperature ( F) Station Avg. Speed (mph) Avg. Direction ( ) Max. Gust (mph) Max. Min. Avg. Total Solar Radiation (MJ/m 2 ) Belleville Big Bend Bondville Brownstown Carbondale Champaign DeKalb Dixon Springs Fairfield Freeport Monmouth Olney Peoria Perry Rend Lake M 48.4 M 72.8 M Snicarte Springfield St. Charles Stelle Table 2. continued Station Average Relative Humidity (%) Total Precip. (in) Average Dew Point ( F) Total Potential Evapotranspiration (in) 4" under Sod Average Soil Temperature ( F) at 8" under Sod 2" under Bare Soil 4" under Bare Soil Belleville Big Bend Bondville Brownstown Carbondale Champaign DeKalb Dixon Springs Fairfield Freeport Monmouth Olney Peoria Perry Rend Lake M 3.84 M Snicarte Springfield St. Charles Stelle M = Missing data. PAGE 5

6 BELLEVILLE CHAMPAIGN BIG BEND DEKALB BONDVILLE DIXON SPRINGS BROWNSTOWN FAIRFIELD CARBONDALE FREEPORT Figure 5. September soil moisture levels at ICN stations: 2 in, 4 in, and 8 in PAGE 6

7 SNICARTE MONMOUTH OLNEY SPRINGFIELD PEORIA ST. CHARLES PERRY STELLE REND LAKE Figure 5. September soil moisture levels at ICN stations: 2 in, 4 in, and 8 in PAGE 7

8 Other Precipitation Networks ERIN BAUER A. IMPERIAL VALLEY y B. COOK COUNTY Imperial Valley. The average network precipitation for September 2018 was 2.82 inches, which is slightly less than the previous 25-year network average (Figure 6a). The largest monthly gage precipitation totals were in the southeast part of Mason County. The smallest gage totals were in central Mason County, east of Havana. Monthly gage totals varied 2.34 inches across the network, from 1.94 inches at site #9, southeast of Topeka, to 4.28 inches at site #16, southwest of San Jose. The year average precipitation amounts for September at Havana and Mason City are 3.15 and 4 inches, respectively. The September 2018 network average of 2.82 inches is 98% of the 25-year ( ) IVWA September network average of 2.88 inches. The Imperial Valley Water Authority funds this 20-station precipitation network operated by the Illinois State Water Survey. Cook County. During September 2018, precipitation in Cook County was near normal (Figure 6b). Gage precipitation amounts were highest in the northern half of the network area, providing above average precipitation for the northern half of the county. The lowest monthly precipitation was measured at four adjacent gages across the middle of the network. Precipitation values ranged from 1.66 inches at site #14 (Chicago, near E. 79th Street and S. Shore Drive) to 4.43 inches at site #4 (Skokie, near Howard St. and Hamlin Ave.). The network average of 2.75 inches is about 94% of the 28-year ( ) September network average of 2.92 inches. The Illinois State Water Survey operates this 25-station precipitation network funded by the U.S. Army Corps of Engineers Figure 6. Precipitation totals (inches) for (a) Imperial Valley Water Authority and (b) Cook County raingage networks September 2018 Surface Water Information BILL SAYLOR River and stream discharge and stage data are obtained from gaging stations operated by the U.S. Geological Survey (USGS) or the U.S. Army Corps of Engineers (USACE). The USGS gaging station network is supported, in part, by the Illinois Department of Natural Resources Office of Water Resources, the Illinois State Water Survey (ISWS), and the USACE. Provisional discharge data are obtained from the USGS. Table 3 lists the provisional peak stage for the current month compared to flood stage at selected streamgaging stations located on the Illinois, Mississippi, and Ohio Rivers. Peak stage is represented here by morning readings posted daily by the USACE or the National Weather Service. Flood stage is defined locally for each gage location. The Mississippi River crested above local flood stages at some locations along the Illinois border in September. PAGE 8

9 Provisional monthly mean flows for 26 streamgaging stations located throughout Illinois are shown in Table 4. Mean values posted by the USGS are listed if available; otherwise, daily mean discharge data posted by the USGS are used to estimate the mean flow for the month. Longterm mean flows for each month are published by the USGS. The month s median flow for each station listed in Table 4 was determined by ranking the September mean flow for each year of record and selecting the middle value, a 50% exceedence probability. The statewide percent of historical mean flow and percent of historical median flow are calculated by dividing the sum of the average flows this month at stations in Table 4 by the sum of the historical mean and median flows calculated for the month, respectively, at the same stations. This method is intended to weight individual observations proportionately in the aggregate comparison. (The Illinois River and Rock River stations are excluded from the statewide calculation because other rivers listed in Table 4 contribute to their flow.) Mean provisional flow aggregated statewide, using the Table 3. Peak Stages for Major Rivers during September 2018 River Station River mile* Flood stage (feet)* Peak stage (feet)** Date Illinois Morris La Salle Peoria Havana Beardstown Hardin Mississippi Dubuque Keokuk Quincy Grafton St. Louis Chester Thebes Ohio Cairo Notes: * River mile and flood stage from River Stages in Illinois: Flood and Damage Data, Illinois Department of Natural Resources, Office of Water Resources, August 2004 (and Addendum, February 2007). ** Peak stage based on daily a.m. readings, not instantaneous peak. Stage data obtained from U.S. Army Corps of Engineers. Table 4. Provisional Mean Flows, September 2018 Station Drainage area (sq mi) Years of record 2018 mean flow (cfs) Long-term flows Mean* (cfs) Median (cfs) Flow condition Percent chance of exceedence Days of data this month Rock River at Rockton 6, ,650 3,036 2,742 much above normal 1 30 Rock River near Joslin 9, ,143 4,453 3,853 much above normal 1 30 Pecatonica River at Freeport 1, , much above normal 1 30 Green River near Geneseo 1, above normal Edwards River near New Boston much above normal 6 30 Kankakee River at Momence 2, , normal Iroquois River near Chebanse 2, normal Fox River at Dayton 2, ,139 1, much above normal 6 30 Vermilion River at Pontiac normal Spoon River at Seville 1, above normal LaMoine River at Ripley 1, , much above normal 8 30 Bear Creek near Marceline above normal Mackinaw River near Congerville normal Salt Creek near Greenview 1, normal Sangamon River at Monticello above normal South Fork Sangamon near Rochester above normal Illinois River at Valley City 26, ,974 12,350 8,279 above normal Macoupin Creek near Kane normal Vermilion River near Danville 1, above normal Kaskaskia River at Vandalia 1, above normal Shoal Creek near Breese above normal Embarras River at Ste. Marie 1, , much above normal 7 30 Skillet Fork at Wayne City , much above normal 1 30 Little Wabash below Clay City 1, , much above normal 3 30 Big Muddy at Plumfield much above normal 4 30 Cache River at Forman above normal Notes: Source streamflow data are obtained from the U.S. Geological Survey. N/A = not available (due to ice or equipment problems). *As reported in U.S. Geological Survey (USGS) Water Resources Data, Illinois, Water Year Much below normal flow = % chance of exceedence. Below normal flow = 70-90% chance of exceedence. Normal flow = 30-70% chance of exceedence. Above normal flow = 10-30% chance of exceedence. Much above normal flow = 0-10% chance of exceedence. PAGE 9

10 available monthly mean data shown this month in Table 4, was above the median value for September (approximately 500% of the median) and above the mean for September (approximately 225% of the mean). Monthly mean discharge values ranged from normal to much above normal for September. September 2018 mean flow values were highest in the period of record for the month of September at the Rock River streamgage at Rockton, the Rock River near Joslin, the Pecatonica River at Freeport, and Skillet Fork at Wayne City. Water-Supply Lakes and Major Reservoirs. Table 5 lists reservoirs in Illinois, their normal pool or target water surface elevation, and other data related to observed variations in water surface elevations. Reservoir levels are obtained from a network of cooperating reservoir operators who are contacted each month by ISWS staff for the current water levels. Reservoir levels are reported in terms of their difference from normal pool (or target level). The average of the month-end readings for the period of record is reported in terms of the difference from normal pool or target level (column 6 of Table 5), and the number of years of record for each reservoir also is given (column 7). Most reservoirs serve as public water supplies, with the exceptions noted in the last column. Compared to end-of-august water levels at 26 reservoirs for which levels were reported last month and this month, reported end-of-september water levels were lower at 11 reservoirs, higher at 10 reservoirs, and about the same as at the end of last month at 5 reservoirs. For the 26 reservoirs with measurements reported at the end of September, water levels were below normal target pool or spillway level at 18 reservoirs, above normal target pool or spillway level at 7 reservoirs, and at about full pool level at 1 reservoir. Major Reservoirs. Compared to water levels at the end of August, at the end of September the water level at Rend Lake was 2.6 feet higher, Carlyle Lake was 0.1 foot higher, Table 5. Reservoir Levels in Illinois, September 2018 Reservoir County Normal pool or target level (feet) Current level difference from normal or target (feet) Monthly change (feet) Average difference from normal or target (feet) Years of record August reported pumpage (million gallons) Altamont Effingham Bloomington McLean N/A Carlinville Macoupin Carlyle (1) Clinton N/A Decatur (1,3) Macon ,091.5 Evergreen (4) Woodford N/A Glenn Shoals (2) Montgomery N/A N/A w/hillsboro Highland Madison Hillsboro (2) Montgomery N/A N/A N/A Jacksonville (2) Morgan w/mauvaise Terre Kinkaid Jackson Lake of Egypt Williamson N/A Mattoon Coles w/paradise Mauvaise Terre (2) Morgan no meter Mt. Olive (new) Macoupin N/A N/A w/mt. Olive (old) Mt. Olive (old) Macoupin Pana Christian N/A Paradise Coles Paris (east) Edgar Not PWS Paris (west) Edgar w/paris (east) Raccoon (1) Marion N/A N/A Rend Franklin N/A Salem (3) Marion Shelbyville (1) Shelby Not PWS Sparta (3) Randolph N/A Spring (3,4) McDonough Springfield (1,3) Sangamon Taylorville Christian Vermilion (4) Vermilion Notes: Normal pool and target level datum is NGVD Current levels reported represent water surface levels at the end of the month, not the monthly average. Average difference from normal or target level is the arithmetic average of reported month-end values for the period of record indicated. Years of record = total number of monthly readings included in month-end average. Total period of record may be longer. Not PWS = not a public water supply. N/A = not available. (1) Target operating level may vary. Seasonal target levels this month represent October 1 values. (2) Instrumentation not available to measure height of water elevation above spillway. (3) Natural inflow can be supplemented by other sources. (4) Normal pool elevations have changed during period of record reported. PAGE 10

11 Table 6. Month-End Shallow Groundwater Level Data Sites, September 2018 No. Well name County Well depth (feet) This month s reading (depth to water, feet) 15-year avg. level (feet) Deviation from Period of record avg. (feet) Previous month (feet) Previous year (feet) 1 Galena JoDaviess Mt. Morris Ogle NA NA NA NA NA 3 Crystal Lake McHenry Fermi Lab DuPage Good Hope McDonough Snicarte Mason Coffman Pike Greenfield Greene Janesville Coles St. Peter Fayette NA NA NA NA NA 11 SWS #2 St. Clair Boyleston Wayne 20 NA NA NA NA NA 13 Sparta Randolph NA 14 SE College Saline Bondville Champaign Averages Notes: N/A = Data not available. and Lake Shelbyville was about the same level. At the end of September, Lake Shelbyville was 0.3 feet above the seasonal target level, Carlyle Lake was 0.9 feet above the seasonal target level, and Rend Lake was 3.5 feet above the spillway level. Great Lakes. Current month mean and end-of-month values are provisional and are relative to International Great Lakes Datum The September 2018 mean level for Lake Michigan was feet. The monthly mean level one year ago (September 2017) was feet. The long-term average lake level for September is feet, based on data. In this period of record, the lowest mean level for Lake Michigan for September occurred in 1964 at feet, and the highest level for September occurred in 1986 at feet. The month-end level of Lake Michigan was feet. All values are provided by the U.S. Army Corps of Engineers Detroit District. Groundwater Information KEN HLINKA Comparison to Average Levels. Shallow groundwater levels in 12 observation wells, which are remote from pumping centers, were above normal for the month of September. Levels averaged 1.2 feet above normal and ranged from 4.3 feet below to 5.2 feet above normal levels (Table 6). Comparison to Previous Month. Shallow groundwater levels were above those of the previous month. Levels averaged 0.2 feet above and ranged from 1.4 feet below to 1.7 feet above levels of August. Comparison to Same Month, Previous Year. Shallow groundwater levels in September were above levels measured one year ago. Levels averaged 1.2 feet above this month and ranged from 5.2 feet below to 4.6 feet above levels of September Data sources for this publication include the following: CPC - Climate Prediction Center, ISWS - Illinois State Water Survey, MRCC - Midwestern Regional Climate Center, NCDC - National Climatic Data Center, NWS - National Weather Service, USACE - U.S. Army Corps of Engineers, USGS - U.S. Geological Survey, WARM - Water and Atmospheric Resources Monitoring Program, ILLINOIS STATE WATER SURVEY Griffith Drive Champaign, IL (217)