Computation Methodology and Additional Statistics

Computed by Jonathan Slemmer

On the previous page, the calculation for 20% above normal temperatures for fog was calculated in this manner:

0.533*(Number of fog occurrences during the 10 previous warmest Februaries) + 0.333*(Number of fog occurrences during the 10 previous closest to normal Februaries) + 0.133*(Number of fog occurrences during the 10 previous coldest Februaries) = Weighted fog frequency for 20% above normal temperatures

Similiarly, the calculation for 20% below normal temperatures for fog was calcula ted in this manner:

0.133*(Number of fog occurrences during the 10 previous warmest Februaries) + 0.333*(Number of fog occurr ences during the 10 previous closest to normal Februaries) + 0.533*(Number of fog occurrences during the 10 previous coldest Februaries) = Weighted fog frequency for 20% below normal temperatures

Frequency of various weather conditions divided into the 10 warmest, 10 coldest, and 10 closest to normal temperature Februaries

The statistics in this table are similair to the previous table but these statistics are not weighted. For example, the 10 warmest Februaries of the past 30 years have had an average frequency of 1 hour of dense fog out of a possible 504 hours (0.2 percent of the time), whereas, during the 10 coldest winters the average frequency of dense fog was 22 hours out of a possible 504 hours (4.4 percent of the time). Thus, when February has above normal temperatures dense fog is much less likely to occur than during average or colder than normal Februaries.

10 Warmest Years
10 Nearest to Normal Years
10 Coldest Years
Dense Fog - 1/4 Statute Mile or Less (without rain/snow):
1
8
22
Moderate or Heavy Snow:
5
2
4
Sustained Winds of 20 mph or Greater:
32
13
13
Wind Gusts of 40 mph or Greater:
3
1
0
Cloud Ceilings of 7000 Feet or Less:
36
36
83
Temperature at or Below Freezing (32 Degrees Farenheit):
114
206
253
Wet Bulb Temperature at or Below 28 Degrees Farenheit (without rain/snow):
71
158
225
Temperature at or Below 15 Degrees Farenheit:
1
11
32
Wind Chill Temperature at or Below 15 Degrees Farenheit:
36
72
121
Wind Shift of at Least 90 Degrees Between Consecutive Hours with Sustained Winds of at Least 8 Knots:
3
4
3
Frontal Passage Defined by Wind Shifts of at Least 90 Degrees Between Consecutiv e Hours with Sustained Winds of at Least 10 mph and a Pressure Jump of at Least 1.5 Milliba rs over 2 hours (from the hour before the wind shift to two hours afterwards):
1
1
1

30 year distribution of the 10 warmest, 10 coldest, and 10 closest to normal temperature Februaries including monthly mean temperature (degrees Farenheit) and total liquid precipitation (inches).

The 10 warmest Februaries were:
1995 - 42.3 F 1.08"
1986 - 41.3 F 1.28"
2000 - 39.8 F 1.80"
1978 - 39.7 F 1.96"
1983 - 39.4 F 1.36"
1992 - 39.2 F 1.24"
1981 - 38.3 F 0.81"
1972 - 37.8 F 0.48"
1998 - 37.5 F 4.89"
1999 - 37.3 F 0.92"

The 10 closest to normal temperature Februaries were:
1991 - 36.5 F 0.61"
1987 - 36.1 F 1.41"
1980 - 36.0 F 2.25"
1977 - 35.8 F 0.64"
1975 - 35.5 F 1.24"
1994 - 35.3 F 1.53"
1997 - 35.2 F 1.62"
2001 - 34.7 F 1.65"
1988 - 34.7 F 0.13"
1976 - 34.1 F 1.90"

The 10 coldest Februaries were:
1990 - 32.8 F 0.35"
1979 - 32.5 F 1.05"
1973 - 32.3 F 0.91"
1982 - 32.3 F 0.53"
1974 - 31.4 F 1.65"
1996 - 30.8 F 1.54"
1993 - 29.5 F 1.35"
1984 - 25.8 F 0.95"
1985 - 25.6 F 0.85"
1989 - 25.3 F 1.57"