| YEAR(S) | JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP | OCT | NOV | DEC | ANN | |||||||||||||
| 1975 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1976 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1977 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1978 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1979 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1980 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1981 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1982 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1983 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1984 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1985 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1986 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1987 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1988 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1989 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1990 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1991 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1992 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1993 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1994 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1995 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1996 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1997 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1998 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 1999 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2000 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2001 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2002 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z |
| 2003 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 27.62 | b | 27.62 | k |
| 2004 | 20.65 | 22.62 | 41.18 | 43.72 | 51.16 | 60.33 | 65.89 | 62.88 | a | 55.25 | 43.73 | 32.05 | 23.72 | b | 43.60 | |||||||||||
| 2005 | 29.00 | b | ----- | z | 32.77 | a | 41.40 | 49.98 | 56.12 | 68.32 | 63.35 | 55.65 | 45.89 | 34.65 | 23.90 | 45.55 | a | |||||||||
| 2006 | 23.31 | 22.55 | 30.05 | 42.95 | 53.96 | h | 63.09 | c | 68.92 | a | 64.44 | 54.32 | 43.52 | 32.53 | 21.69 | 42.49 | a | |||||||||
| 2007 | 16.05 | 26.71 | 37.94 | 43.40 | a | 51.00 | 61.59 | b | 70.74 | 67.31 | 56.17 | 44.06 | 36.82 | 18.02 | 44.15 | |||||||||||
| 2008 | 17.00 | 22.47 | 27.80 | a | ----- | z | ----- | z | 57.60 | 67.82 | 65.15 | 56.15 | 45.06 | 36.92 | 22.03 | 41.80 | b | |||||||||
| 2009 | 23.42 | 27.07 | a | 33.66 | c | 39.33 | 51.76 | 55.82 | 67.10 | 64.18 | 58.87 | 40.00 | a | 34.65 | 16.69 | 42.71 | ||||||||||
| 2010 | 23.89 | 24.89 | 31.74 | 39.35 | 44.84 | b | 58.33 | 66.55 | 63.05 | 58.47 | a | 46.58 | a | 28.65 | 28.76 | 42.93 | ||||||||||
| 2011 | 18.39 | 20.12 | ----- | z | 37.98 | 45.69 | 57.09 | a | 66.18 | 65.63 | 57.98 | 44.69 | 31.53 | 21.76 | 42.46 | a | ||||||||||
| 2012 | 27.45 | 25.41 | 35.60 | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | ----- | z | 29.49 | i | |||
| Period of Record Statistics | ||||||||||||||||||||||||||
| MEAN | 22.13 | 23.98 | 33.84 | 41.16 | 49.07 | 58.75 | 67.69 | 64.50 | 56.61 | 44.19 | 33.48 | 22.69 | 43.35 | |||||||||||||
| S.D. | 4.49 | 2.42 | 4.31 | 2.29 | 3.01 | 2.65 | 1.62 | 1.50 | 1.64 | 2.00 | 2.82 | 3.93 | 0.66 | |||||||||||||
| SKEW | 0.10 | -0.14 | 0.35 | -0.16 | -0.62 | 0.49 | 0.70 | 0.69 | 0.17 | -1.05 | -0.29 | 0.06 | 0.28 | |||||||||||||
| MAX | 29.00 | 27.07 | 41.18 | 43.72 | 51.76 | 63.09 | 70.74 | 67.31 | 58.87 | 46.58 | 36.92 | 28.76 | 44.15 | |||||||||||||
| MIN | 16.05 | 20.13 | 27.80 | 37.98 | 44.84 | 55.82 | 65.89 | 62.88 | 54.32 | 40.00 | 28.65 | 16.69 | 42.71 | |||||||||||||
| YRS | 9 | 8 | 8 | 7 | 6 | 8 | 8 | 8 | 8 | 8 | 8 | 9 | 4 | |||||||||||||