| YEAR(S) | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP | OCT | NOV | DEC | ANN | |||||||||||||
| 1956 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 15.93 | b | 12.33 | d | 14.13 | |
| 1957 | 0.14 | i | 22.38 | l | 28.90 | b | 29.71 | b | 40.42 | 45.04 | c | 45.61 | c | 38.83 | b | 33.76 | i | 31.23 | 20.93 | c | 19.25 | c | 33.32 | |||
| 1958 | 21.50 | a | 29.00 | g | 24.07 | b | 28.75 | b | 36.57 | c | 42.07 | a | 49.64 | c | 51.68 | i | 39.83 | x | 26.55 | b | 15.12 | e | 20.79 | c | 29.45 | |
| 1959 | 22.19 | 20.23 | b | 21.71 | 29.23 | 35.07 | d | 44.50 | 50.87 | 45.48 | b | 40.73 | 31.77 | 15.33 | 9.07 | c | 30.52 | |||||||||
| 1960 | 13.48 | 21.97 | 27.53 | a | 28.24 | a | 35.55 | b | 48.04 | d | 49.19 | 43.48 | 38.75 | b | 28.55 | 26.97 | 18.57 | a | 31.69 | |||||||
| 1961 | 16.03 | 26.92 | b | 26.42 | 28.23 | 32.96 | e | 48.59 | a | 50.48 | b | 52.91 | h | 38.62 | a | 31.21 | c | 19.00 | b | 15.87 | h | 31.85 | ||||
| 1962 | 7.10 | a | 18.05 | g | 23.93 | c | 33.61 | g | 36.92 | f | 43.52 | a | 48.56 | f | 47.18 | c | 39.64 | b | ----- | z | 27.00 | d | 26.40 | k | 31.39 | |
| 1963 | 8.15 | e | 30.11 | 28.76 | f | 27.70 | 40.46 | g | 41.14 | a | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 26.77 | |||
| 1964 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 9999.00 | |
| 1965 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 9999.00 | |
| 1966 | ----- | z | ----- | z | ----- | z | ----- | z | 37.45 | i | 43.53 | k | 47.04 | g | 48.52 | d | 39.15 | d | ----- | z | 27.76 | e | 20.19 | d | 33.90 | |
| 1967 | 18.46 | e | 22.00 | e | 24.81 | d | ----- | z | 38.52 | f | 44.19 | d | 51.70 | d | ----- | z | 45.19 | d | 28.81 | e | ----- | z | ----- | z | 33.60 | |
| 1968 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 47.00 | f | 52.71 | 44.52 | 40.80 | 32.73 | a | 29.03 | 15.58 | 35.90 | ||||||
| 1969 | 18.61 | 18.11 | 22.65 | 29.47 | 39.57 | a | 46.60 | 51.71 | 44.94 | 40.62 | d | 26.58 | 19.83 | 20.84 | 31.63 | |||||||||||
| 1970 | 23.81 | 23.39 | 24.16 | 24.30 | ----- | z | 45.50 | 48.35 | 44.84 | 31.70 | 24.00 | ----- | z | 19.37 | a | 30.94 | ||||||||||
| 1971 | 20.94 | 22.93 | 22.84 | 26.97 | 35.68 | 39.60 | 48.58 | 45.90 | 33.87 | 26.71 | 23.30 | 10.84 | 29.85 | |||||||||||||
| 1972 | 12.23 | 23.45 | 26.93 | a | 27.00 | 37.48 | 47.40 | 50.21 | c | 45.68 | l | 34.48 | i | 31.94 | 29.03 | ----- | z | 31.74 | ||||||||
| 1973 | 9.35 | n | 23.71 | 26.32 | 29.83 | ----- | z | ----- | z | 52.83 | b | 46.26 | ----- | z | ----- | z | 27.90 | 26.50 | e | 33.34 | ||||||
| 1974 | 17.65 | 20.96 | 29.58 | 27.63 | 34.29 | 46.70 | 49.00 | b | 46.18 | c | ----- | z | ----- | z | ----- | z | ----- | z | 34.00 | |||||||
| 1975 | ----- | z | ----- | z | ----- | z | 25.13 | o | 34.77 | a | 42.96 | f | 51.88 | f | 45.75 | c | ----- | z | 31.87 | a | ----- | z | 15.40 | k | 37.46 | |
| 1976 | 14.79 | b | 25.00 | a | 22.97 | b | 27.12 | d | 38.67 | a | 41.73 | d | 51.26 | 45.96 | c | 43.60 | 29.13 | a | ----- | z | 7.68 | c | 31.63 | |||
| 1977 | 4.53 | a | 21.22 | a | 21.31 | b | 30.03 | a | 34.13 | 50.52 | a | 51.54 | c | 52.43 | a | 40.59 | a | 31.79 | c | 22.66 | a | 23.22 | d | 32.00 | ||
| 1978 | 25.38 | b | 26.93 | ----- | z | 33.04 | b | 37.06 | 43.52 | a | 51.17 | b | 47.58 | 39.30 | c | 31.72 | b | 19.76 | a | 11.03 | b | 33.32 | ||||
| 1979 | 10.10 | 24.41 | a | 27.90 | b | 31.87 | g | 39.74 | 44.43 | b | 52.19 | e | ----- | z | 40.25 | f | 35.93 | a | 17.65 | d | 14.59 | b | 29.66 | |||
| 1980 | 20.10 | a | 26.56 | d | 24.36 | c | 32.59 | a | 38.97 | b | 38.44 | e | 50.52 | d | 47.13 | 42.17 | a | 31.14 | b | ----- | z | 19.00 | l | 35.20 | ||
| 1981 | 20.69 | b | 24.08 | d | 25.34 | b | 31.90 | j | 37.07 | a | 46.52 | c | 49.72 | m | 50.90 | k | 43.38 | d | 29.30 | d | 28.04 | c | 24.29 | c | 30.97 | |
| 1982 | 11.77 | 18.71 | 25.58 | 26.38 | i | 33.94 | 43.93 | 50.45 | ----- | z | 41.27 | 30.84 | 22.17 | 19.62 | r | 30.96 | ||||||||||
| 1983 | 22.77 | 27.46 | b | 31.00 | 28.60 | 36.74 | 43.03 | 47.65 | 51.94 | 42.48 | a | 33.39 | 27.00 | 22.52 | 34.55 | |||||||||||
| 1984 | 5.06 | 16.93 | 28.26 | 30.50 | 40.03 | 41.93 | ----- | z | 51.77 | 39.50 | 30.35 | 26.83 | a | 12.76 | j | 31.12 | ||||||||||
| 1985 | 12.19 | 15.36 | 21.23 | 32.57 | 38.23 | 49.90 | a | 55.26 | l | 46.36 | i | 38.53 | 29.19 | 15.43 | 5.09 | t | 28.07 | |||||||||
| 1986 | 23.29 | 30.11 | a | 29.83 | m | 30.33 | 36.35 | 50.14 | w | 50.09 | t | 52.38 | o | 38.13 | 31.82 | i | 21.57 | 12.32 | l | 29.96 | ||||||
| 1987 | 10.77 | 24.54 | 25.42 | 32.63 | 42.35 | 46.77 | 48.74 | 50.19 | 41.77 | 34.61 | 26.13 | 18.00 | 33.49 | |||||||||||||
| 1988 | 11.03 | 20.55 | 24.10 | 34.04 | e | 37.87 | 50.50 | 56.23 | 51.23 | 41.20 | 36.81 | 26.80 | j | 14.71 | 34.39 | |||||||||||
| 1989 | 7.81 | 11.14 | 31.87 | 34.97 | 39.94 | 47.43 | 50.84 | 47.00 | 42.30 | 32.45 | 19.83 | 14.65 | 31.69 | |||||||||||||
| 1990 | 19.90 | 16.43 | 26.52 | 38.53 | 38.58 | 45.37 | 55.00 | 52.61 | 46.37 | 31.68 | 20.57 | 3.68 | 32.94 | |||||||||||||
| 1991 | 13.81 | 24.86 | 27.32 | 32.23 | 36.16 | 40.43 | 52.45 | 51.65 | 44.50 | 33.77 | 28.77 | 16.65 | 33.55 | |||||||||||||
| 1992 | 19.16 | 26.59 | 27.42 | 36.37 | 46.26 | 49.00 | 51.32 | 51.94 | 43.23 | 36.06 | 24.83 | 16.35 | 35.71 | |||||||||||||
| 1993 | 6.84 | 15.79 | 34.47 | a | 33.10 | 42.13 | 43.27 | 46.55 | 48.65 | 41.33 | 35.00 | 14.70 | 18.23 | 31.67 | ||||||||||||
| 1994 | 18.39 | 18.04 | 28.84 | 34.50 | 42.94 | 45.83 | 56.48 | 50.58 | 43.93 | 31.55 | 18.67 | 10.23 | 33.33 | |||||||||||||
| 1995 | 25.90 | 28.25 | 29.19 | ----- | z | 40.81 | 42.80 | 49.81 | 47.52 | 41.17 | 30.70 | a | 25.79 | b | 22.03 | 34.91 | ||||||||||
| 1996 | 21.68 | 21.69 | 27.47 | a | 31.87 | 37.36 | q | 46.20 | 53.10 | 50.03 | 38.37 | 32.74 | 26.17 | 25.19 | 34.05 | |||||||||||
| 1997 | 20.10 | 24.11 | 28.74 | 31.00 | ----- | z | 45.73 | 51.17 | a | 49.81 | 42.87 | 32.16 | 27.97 | 18.87 | 33.87 | |||||||||||
| 1998 | 26.19 | 25.61 | 27.74 | 30.97 | 39.00 | ----- | z | 55.94 | 51.42 | 48.03 | 33.26 | 27.90 | 15.52 | 34.69 | ||||||||||||
| 1999 | 23.36 | f | 26.67 | d | 28.00 | f | 29.04 | f | 37.67 | d | 47.68 | e | 51.92 | e | 51.32 | f | 40.22 | c | 31.03 | b | 25.96 | e | 14.27 | e | 34.43 | |
| 2000 | 20.45 | 27.17 | 27.86 | b | 33.93 | c | 36.82 | i | 42.40 | e | 50.93 | c | 51.91 | h | 41.28 | a | 32.03 | b | 19.83 | f | 16.92 | r | 34.51 | |||
| 2001 | 13.11 | c | 20.79 | d | 29.23 | a | 28.52 | e | 40.87 | a | 39.00 | j | 44.19 | e | 48.21 | b | 41.17 | a | 34.89 | d | 23.38 | d | 17.41 | d | 31.07 | |
| 2002 | 18.94 | 23.82 | 21.26 | 30.93 | 33.77 | i | 46.25 | j | 55.00 | 47.64 | c | ----- | z | 26.35 | 21.63 | 22.29 | 29.76 | |||||||||
| 2003 | 27.68 | 18.07 | 28.35 | 27.80 | j | 43.76 | j | 47.50 | 54.35 | 50.97 | 40.60 | e | 34.58 | 17.40 | 21.61 | c | 34.11 | |||||||||
| 2004 | 11.13 | 14.35 | i | 29.19 | 32.40 | 35.28 | f | 47.30 | 54.16 | ----- | z | 39.87 | 33.42 | 23.73 | 20.13 | 32.37 | ||||||||||
| 2005 | 8.73 | e | 18.00 | 28.42 | 30.70 | 40.10 | 40.47 | 53.52 | 48.44 | f | 35.67 | ----- | z | 18.33 | 17.29 | 29.12 | ||||||||||
| 2006 | 23.22 | d | 17.23 | f | 23.26 | 28.08 | e | 36.29 | 44.58 | f | 53.26 | ----- | z | 40.00 | r | 29.68 | i | 22.63 | 11.74 | d | 28.35 | |||||
| 2007 | 10.90 | ----- | z | 28.83 | a | 30.67 | 40.77 | 47.77 | 56.42 | 49.87 | 40.87 | 32.68 | 23.63 | 16.52 | f | 36.24 | ||||||||||
| 2008 | 8.42 | e | 18.59 | g | 24.81 | 26.10 | 38.00 | 44.80 | 53.03 | 50.74 | ----- | z | 30.55 | 27.64 | e | 11.19 | 31.53 | |||||||||
| 2009 | 15.83 | g | 22.86 | 25.13 | 29.20 | 42.52 | b | 46.83 | 54.29 | ----- | z | 45.60 | 30.13 | 21.77 | 8.85 | d | 32.72 | |||||||||
| 2010 | 21.72 | f | 24.89 | 24.31 | e | ----- | z | 33.77 | 46.73 | 53.29 | 48.19 | 40.40 | 36.28 | f | 23.03 | 24.32 | 35.44 | |||||||||
| 2011 | 16.93 | a | 19.85 | b | 29.17 | a | 29.38 | a | 35.30 | a | ----- | z | ----- | z | 50.83 | a | 43.54 | b | 33.59 | b | 20.55 | a | ----- | z | 31.01 | |
| 2012 | 15.62 | b | 20.52 | d | 28.94 | 32.07 | ----- | z | 44.63 | 53.71 | 50.94 | 43.14 | a | 31.55 | 26.87 | 19.84 | 33.44 | |||||||||
| 2013 | 2.55 | 23.21 | 25.00 | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 12.88 | |||
| Period of Record Statistics | ||||||||||||||||||||||||||
| MEAN | 15.96 | 22.53 | 26.50 | 30.57 | 38.12 | 45.14 | 51.59 | 48.39 | 41.06 | 31.47 | 22.96 | 16.99 | 32.51 | |||||||||||||
| S.D. | 6.48 | 4.12 | 2.94 | 2.88 | 2.95 | 2.90 | 2.78 | 3.02 | 3.04 | 2.74 | 4.30 | 5.33 | 1.62 | |||||||||||||
| SKEW | -0.17 | -0.42 | 0.11 | 0.42 | 0.42 | -0.25 | -0.38 | -0.79 | -0.57 | -0.51 | -0.33 | -0.39 | 0.30 | |||||||||||||
| MAX | 27.68 | 30.11 | 34.47 | 38.53 | 46.26 | 50.52 | 56.48 | 52.61 | 48.03 | 36.81 | 29.03 | 26.50 | 35.71 | |||||||||||||
| MIN | 2.55 | 11.14 | 21.23 | 24.30 | 32.96 | 38.44 | 44.19 | 38.83 | 31.70 | 24.00 | 14.70 | 3.68 | 29.85 | |||||||||||||
| NO YRS | 47 | 45 | 47 | 42 | 40 | 44 | 45 | 38 | 43 | 45 | 46 | 40 | 13 | |||||||||||||