Table 1. Sectional Mean Frequency Distributions for Storm Periods of 5 Minutes to 10 Days and Recurrence Intervals of 1 to 100 Years in Illinois. Amounts are in inches. Sectional code 01 - Northwest 06 - West Southwest 02 - Northeast 07 - East Southeast 03 - West 08 - Southwest 04 - Central 09 - Southeast 05 - East 10 - South Section Duration 1-year 2-year 5-year 10-year 25-year 50-year 100-year 01 10-day 4.37 5.23 6.30 7.14 8.39 9.64 11.09 01 5-day 3.45 4.13 5.10 5.91 7.21 8.36 9.97 01 72-hr 3.06 3.73 4.67 5.42 6.59 7.64 8.87 01 48-hr 2.80 3.42 4.28 4.96 6.07 7.02 8.07 01 24-hr 2.57 3.11 3.95 4.63 5.60 6.53 7.36 01 18-hr 2.37 2.86 3.63 4.26 5.15 6.01 6.92 01 12-hr 2.24 2.71 3.43 4.03 4.88 5.66 6.51 01 6-hr 1.93 2.33 2.96 3.48 4.20 4.90 5.69 01 3-hr 1.65 1.99 2.53 2.97 3.59 4.18 4.90 01 2-hr 1.52 1.83 2.33 2.74 3.31 3.86 4.47 01 1-hr 1.21 1.46 1.86 2.18 2.63 3.07 3.51 01 30-min 0.95 1.15 1.46 1.71 2.07 2.42 2.77 01 15-min 0.70 0.84 1.07 1.25 1.51 1.76 1.99 01 10-min 0.57 0.68 0.87 1.02 1.23 1.44 1.62 01 5-min 0.31 0.37 0.47 0.56 0.67 0.78 0.89 02 10-day 4.12 4.95 6.04 6.89 8.18 9.38 11.14 02 5-day 3.25 3.93 4.91 5.70 6.93 8.04 9.96 02 72-hr 2.93 3.55 4.44 5.18 6.32 7.41 8.78 02 48-hr 2.70 3.30 4.09 4.81 5.88 6.84 8.16 02 24-hr 2.51 3.04 3.80 4.47 5.51 6.46 7.58 02 18-hr 2.30 2.79 3.50 4.11 5.06 5.95 6.97 02 12-hr 2.18 2.64 3.31 3.89 4.79 5.62 6.59 02 6-hr 1.88 2.28 2.85 3.35 4.13 4.85 5.68 02 3-hr 1.60 1.94 2.43 2.86 3.53 4.14 4.85 02 2-hr 1.48 1.79 2.24 2.64 3.25 3.82 4.47 02 1-hr 1.18 1.43 1.79 2.10 2.59 3.04 3.56 02 30-min 0.93 1.12 1.41 1.65 2.04 2.39 2.80 02 15-min 0.68 0.82 1.03 1.21 1.49 1.75 2.05 02 10-min 0.55 0.67 0.84 0.98 1.21 1.42 1.67 02 5-min 0.30 0.36 0.46 0.54 0.66 0.78 0.91 03 10-day 4.60 5.60 6.91 7.89 9.24 10.36 11.90 03 5-day 3.71 4.57 5.80 6.65 7.90 8.95 10.50 03 72-hr 3.30 4.08 5.11 5.87 6.97 7.95 9.48 03 48-hr 3.01 3.68 4.56 5.50 6.45 7.56 8.80 03 24-hr 2.79 3.45 4.29 4.93 6.07 7.04 8.20 03 18-hr 2.57 3.18 3.95 4.53 5.59 6.47 7.55 03 12-hr 2.43 2.98 3.73 4.29 5.28 6.13 7.14 03 6-hr 2.10 2.58 3.22 3.70 4.55 5.28 6.15 03 3-hr 1.79 2.21 2.75 3.15 3.89 4.51 5.25 03 2-hr 1.65 2.02 2.53 2.91 3.58 4.15 4.84 03 1-hr 1.31 1.60 2.02 2.32 2.86 3.31 3.85 03 30-min 1.03 1.27 1.59 1.82 2.25 2.61 3.03 03 15-min 0.75 0.91 1.16 1.33 1.64 1.90 2.21 03 10-min 0.61 0.74 0.94 1.08 1.33 1.55 1.81 03 5-min 0.33 0.40 0.51 0.59 0.73 0.84 0.98 Section Duration 1-year 2-year 5-year 10-year 25-year 50-year 100-year 04 10-day 4.29 5.12 6.27 7.10 8.19 9.10 10.18 04 5-day 3.48 4.17 5.11 5.84 6.96 7.98 9.21 04 72-hr 3.05 3.70 4.55 5.26 6.15 7.25 8.16 04 48-hr 2.81 3.38 4.19 4.86 5.78 6.62 7.51 04 24-hr 2.52 3.02 3.76 4.45 5.32 6.08 6.92 04 18-hr 2.28 2.75 3.46 4.09 4.90 5.59 6.37 04 12-hr 2.17 2.62 3.27 3.87 4.63 5.29 6.02 04 6-hr 1.89 2.26 2.82 3.33 3.99 4.56 5.19 04 3-hr 1.61 1.93 2.41 2.85 3.41 3.89 4.43 04 2-hr 1.48 1.78 2.22 2.62 3.14 3.59 4.08 04 1-hr 1.18 1.42 1.77 2.09 2.50 2.86 3.25 04 30-min 0.93 1.12 1.39 1.64 1.97 2.25 2.56 04 15-min 0.68 0.81 1.02 1.20 1.44 1.64 1.87 04 10-min 0.55 0.66 0.83 0.98 1.17 1.34 1.52 04 5-min 0.30 0.36 0.45 0.53 0.64 0.73 0.83 05 10-day 4.35 5.15 6.21 6.97 8.04 8.90 9.92 05 5-day 3.42 4.12 4.96 5.67 6.76 7.65 8.78 05 72-hr 3.10 3.71 4.57 5.20 6.17 6.97 7.83 05 48-hr 2.82 3.40 4.16 4.77 5.66 6.40 7.16 05 24-hr 2.47 3.01 3.71 4.26 5.04 5.83 6.61 05 18-hr 2.27 2.77 3.41 3.92 4.63 5.37 6.08 05 12-hr 2.15 2.62 3.23 3.71 4.38 5.08 5.75 05 6-hr 1.85 2.26 2.78 3.20 3.78 4.38 4.96 05 3-hr 1.58 1.93 2.37 2.73 3.22 3.74 4.23 05 2-hr 1.46 1.78 2.19 2.52 2.97 3.44 3.90 05 1-hr 1.16 1.41 1.74 2.00 2.39 2.74 3.11 05 30-min 0.91 1.11 1.37 1.57 1.87 2.16 2.45 05 15-min 0.67 0.81 1.00 1.14 1.37 1.60 1.85 05 10-min 0.54 0.66 0.81 0.94 1.12 1.28 1.46 05 5-min 0.30 0.36 0.44 0.51 0.61 0.70 0.79 06 10-day 4.40 5.35 6.62 7.45 8.66 9.79 11.26 06 5-day 3.47 4.19 5.32 6.20 7.44 8.53 9.93 06 72-hr 3.13 3.81 4.85 5.68 6.84 7.76 8.92 06 48-hr 2.87 3.49 4.45 5.21 6.28 7.12 8.19 06 24-hr 2.59 3.11 3.93 4.65 5.57 6.46 7.45 06 18-hr 2.38 2.86 3.61 4.28 5.12 5.95 6.85 06 12-hr 2.25 2.71 3.39 3.97 4.84 5.62 6.48 06 6-hr 1.94 2.33 2.95 3.48 4.18 4.85 5.59 06 3-hr 1.66 1.99 2.51 2.98 3.56 4.14 4.77 06 2-hr 1.53 1.84 2.32 2.74 3.28 3.81 4.39 06 1-hr 1.21 1.46 1.85 2.19 2.62 3.04 3.50 06 30-min 0.96 1.15 1.46 1.72 2.06 2.39 2.75 06 15-min 0.70 0.84 1.06 1.26 1.52 1.75 2.01 06 10-min 0.57 0.68 0.87 1.02 1.22 1.42 1.64 06 5-min 0.31 0.37 0.47 0.56 0.67 0.78 0.89 Section Duration 1-year 2-year 5-year 10-year 25-year 50-year 100-year 07 10-day 4.64 5.58 6.80 7.61 8.66 9.70 10.87 07 5-day 3.63 4.34 5.33 6.11 7.28 8.37 9.65 07 72-hr 3.12 3.73 4.64 5.32 6.39 7.35 8.54 07 48-hr 2.87 3.42 4.26 4.88 5.84 6.75 8.00 07 24-hr 2.55 3.03 3.80 4.44 5.37 6.23 7.41 07 18-hr 2.35 2.79 3.49 4.08 4.94 5.73 6.81 07 12-hr 2.22 2.63 3.30 3.86 4.67 5.42 6.45 07 6-hr 1.87 2.27 2.85 3.33 4.03 4.67 5.56 07 3-hr 1.63 1.94 2.43 2.84 3.44 3.99 4.74 07 2-hr 1.50 1.79 2.24 2.62 3.17 3.67 4.39 07 1-hr 1.20 1.42 1.78 2.09 2.52 2.93 3.48 07 30-min 0.93 1.12 1.41 1.64 1.99 2.31 2.74 07 15-min 0.69 0.82 1.03 1.20 1.45 1.68 2.00 07 10-min 0.56 0.66 0.83 0.98 1.18 1.37 1.63 07 5-min 0.31 0.36 0.46 0.54 0.64 0.75 0.89 08 10-day 4.54 5.54 6.80 7.80 9.20 10.44 11.81 08 5-day 3.62 4.40 5.46 6.34 7.68 8.88 10.68 08 72-hr 3.22 3.94 4.92 5.74 6.97 8.12 9.55 08 48-hr 4.52 5.26 6.43 7.36 8.81 08 24-hr 4.13 4.76 6.02 7.07 8.21 08 18-hr 3.80 4.38 5.54 6.51 7.55 08 12-hr 3.60 4.14 5.24 6.15 7.14 08 6-hr 2.03 2.45 3.10 3.57 4.52 5.30 6.16 08 3-hr 1.73 2.10 2.63 3.08 3.86 4.52 5.25 08 2-hr 1.60 1.94 2.44 2.87 3.55 4.20 4.84 08 1-hr 1.26 1.54 1.93 2.27 2.84 3.32 3.86 08 30-min 1.00 1.22 1.53 1.78 2.25 2.62 3.03 08 15-min 0.73 0.89 1.12 1.29 1.63 1.91 2.22 08 10-min 0.60 0.72 0.91 1.05 1.32 1.55 1.81 08 5-min 0.33 0.40 0.50 0.58 0.72 0.85 0.99 09 10-day 4.75 5.74 7.09 8.07 9.54 10.68 11.79 09 5-day 3.75 4.48 5.57 6.50 7.91 9.16 10.57 09 72-hr 3.27 3.92 4.92 5.75 7.05 8.23 9.40 09 48-hr 3.00 3.60 4.52 5.28 6.48 7.58 8.62 09 24-hr 2.62 3.16 4.00 4.62 5.79 6.71 7.73 09 18-hr 2.41 2.91 3.68 4.25 5.33 6.17 7.11 09 12-hr 2.28 2.75 3.48 4.02 5.04 5.84 6.72 09 6-hr 1.97 2.37 3.00 3.47 4.34 5.03 5.80 09 3-hr 1.68 2.02 2.56 2.96 3.71 4.29 4.95 09 2-hr 1.55 1.85 2.36 2.72 3.41 3.96 4.56 09 1-hr 1.23 1.49 1.88 2.20 2.72 3.15 3.63 09 30-min 0.97 1.17 1.47 1.73 2.14 2.48 2.86 09 15-min 0.71 0.85 1.08 1.25 1.56 1.81 2.09 09 10-min 0.58 0.70 0.88 1.02 1.27 1.48 1.70 09 5-min 0.32 0.38 0.48 0.55 0.69 0.81 0.93 Section Duration 1-year 2-year 5-year 10-year 25-year 50-year 100-year 10 10-day 5.26 6.36 7.81 8.90 10.34 11.36 12.50 10 5-day 4.10 4.99 6.20 7.21 8.45 9.45 10.82 10 72-hr 3.59 4.36 5.48 6.34 7.53 8.54 9.52 10 48-hr 3.30 4.00 5.03 5.80 6.93 7.86 8.79 10 24-hr 2.97 3.62 4.51 5.21 6.23 7.11 8.27 10 18-hr 2.74 3.33 4.15 4.79 5.74 6.54 7.61 10 12-hr 2.59 3.15 3.93 4.53 5.42 6.19 7.20 10 6-hr 2.23 2.73 3.39 3.91 4.68 5.31 6.21 10 3-hr 1.90 2.32 2.89 3.33 3.99 4.55 5.29 10 2-hr 1.76 2.14 2.66 3.07 3.68 4.20 4.88 10 1-hr 1.40 1.70 2.12 2.45 2.93 3.34 3.89 10 30-min 1.10 1.34 1.66 1.93 2.31 2.63 3.06 10 15-min 0.80 0.98 1.22 1.41 1.68 1.92 2.23 10 10-min 0.65 0.80 0.99 1.14 1.37 1.56 1.82 10 5-min 0.36 0.43 0.54 0.62 0.75 0.85 0.99 Reference: Huff, F. A., and J. R. Angel, 1989. "Frequency distributions and hydroclimatic characteristics of heavy rainstorms in Illinois", Illinois State Water Survey Bulletin 70, Champaign, IL, 177 pp. ------------------------------------------------------------------------------- Jim Angel, State Climatologist, j-angel@illlinois.edu Illinois Water Survey, Champaign, IL Last Modified: January 21, 1998