Brian F. O'Hara and Lance W. Pyle
National Weather Service Forecast Office
North Webster, Indiana
The climate of northeastern Indiana is generally considered continental, although the nearness of the Great Lakes can modify local weather considerably. Winters tend to be cold with average daytime high temperatures (in Fahrenheit) in the 30s and lows in the teens to lower 20s. The passage of strong cold fronts can plunge temperatures to 10 to 20 degrees below zero. The winter months of January and February tend to be the driest with average precipitation totals of less than 2 inches each month. However, heavy snowfalls do occur and, when combined with the cold temperatures, snow can remain on the ground for weeks.
Fort Wayne, Indiana receives an average of 35 inches of snowfall each winter. Annual snowfall totals however can vary greatly from this average. In the 79 years of this study (covering the winter seasons 1920-21 through 1998-99) the highest total was recorded in 1981-82 when 81.2 inches of snow fell (29.5 inches of snow fell in January alone). The least amount during this 79 year period was in 1931-32 when only 8.3 inches of snow fell. Figure 1 shows the average annual snowfall for Fort Wayne. It shows the relatively dry winter seasons of the 1920s, 1930s, and 1940s and the relatively moist 1970s, and 1980s.
Figure 1. Average annual snowfall (in) by decade for Fort Wayne, Indiana.
As a further study of the winter climate in northeastern Indiana, a snow cover climatology was compiled. Wassall (1973) was the inspiration for this climatology. It is a very readable article containing a wealth of information.
The authors feel that this snow cover climatology for Fort Wayne will be useful to forecasters in a number of ways. First, it should help forecasters who are new to the area become familiar with what both average and extreme winter conditions can be like in northeastern Indiana. Second, it can give them an idea of the possibility of spring flooding when substantial snow cover lasts into March. Some of the largest spring floods (notably those of 1978, 1982, and 1985) have resulted from snowmelt, especially when combined with rainfall.
Finally, a knowledge of what snow cover conditions have been like in the past can help forecasters determine whether a winter season is actually severe or not. This climatology describes snow cover experienced during most of this last century at Fort Wayne. With the current interest in issues such as global warming and El Nino (by the public, media, and meteorologists), this study of almost 80 years of data can help forecasters see whether the winter climate (at least here in northeastern Indiana) has changed much during these years and how current conditions compare to some of the more extreme winters from the past.
To compile the data for the climatology, the monthly Local Climatological Data (LCD) records for Fort Wayne, Indiana were used. The official U.S. Weather Bureau, National Weather Service office has been at a number of locations in Fort Wayne since it was established in May 1911. Official weather observations were taken at various locations in downtown Fort Wayne from 1911 until 1939. In July 1939, regular weather observations began at what is now Smith Field, north of Fort Wayne. Then in December 1946, the office was moved to Baer Field, south of town. This location is the current Fort Wayne International Airport (FWA).
One of the parameters listed in a LCD is the amount of frozen precipitation (snow, ice, ice pellets, hail, etc.) present on the ground at the same time each day. These readings are reported to the nearest inch. Such instaneous readings do not necessarily represent the maximum snow on the ground on a given day, but they are representative of general snow-cover conditions (Wassall 1973).
These snow cover amounts at Fort Wayne were being reported daily at 7:00 p.m. Central Standard Time (CST) in 1920, the year this 79-year study period began. The reporting time was changed to 6:30 p.m. CST in November 1939. Snow cover and ice on the ground continued to be reported daily at 6:30 p.m. CST until the summer of 1952. In July 1952, the observation time was changed to the morning at 6:30 a.m. CST. In June 1957, the observation time was changed to 6:00 a.m. CST. In September 1961, the Fort Wayne LCDs started listing the observation time as 7:00 a.m. Eastern Standard Time (EST) (7:00 a.m. EST being equal to the previous listing of 6:00 a.m. CST).
Snow cover at Fort Wayne was reported to the nearest tenth-of-an-inch until December 1948. Since January 1949, daily snow cover has been reported to the nearest inch. For the purposes of this study, snow cover amounts before 1949 were converted to the nearest inch.
It should be noted that from January 1941 through December 1942, snow cover was not reported daily. It was only reported twice a month; the 15thand the last day of the month. To have as complete a record as possible of daily snow cover, the authors studied snowfall amounts and daily temperature readings that were recorded during these two years and estimated what the snow cover might have been for this period. This was accomplished by studying years with complete data. We were able to see how snow cover was affected as different amounts of daily snowfall and average temperature departures from normal were recorded. The amounts reported on the 15th and last day of each month proved helpful in determining snow cover trends for these years.
Figure 2 shows the total number of years that various snow cover amounts were reported for each day contained in the study. The graph depicts a fairly typical bell shape but it's not very smooth. Since the period of study comprises only 79 years, daily totals (just days apart) can vary considerably. For example, a trace or more of snow cover has been reported on December 8 in 21 of the 79 seasons studied, while a trace or more was reported on December 11 (three days later) 41 times (52 percent) during this period.
This is quite a difference. This may be when the first snowfall of the season has often occurred during the period of study. However, by looking at Figure 2, it can be seen that there is also a peak in late-November. This earlier peak in the data may be the result of a few snowstorms that have occurred during the last week of November at Fort Wayne. With a larger database these daily totals would possibly start to approach the shape of a smooth curve. However, the current graph clearly demonstrates the trend of increasing snow cover through early-winter, reaching a peak in late-January, and then decreasing fairly rapidly.
Figure 2. Frequency of years reporting indicated snow depths for each date of snow seasons from 1920-21 through 1998-99 for Fort Wayne, Indiana.
Throughout October and most of November, the probability of at least a trace of snow cover being reported on any given day at Fort Wayne is small, only 30 percent by late-November. By mid-December, however, the percentage increases to 50 percent. The probability of at least a trace of snow cover continues to increase through the winter season, reaching a maximum of 77 percent (61 out of 79 years) on January 29. During the 79 year period of study the occurrence of at least a trace of snow cover remained at or above 60 percent from January 2 through February 17, and there was at least a 40 percent chance from December 10 through March 4. The probability of at least a trace of snow cover decreases fairly quickly thereafter, falling below 20 percent by late-March. Table 1 lists the periods that at least a trace of snow cover was reported continuously during the seventy-nine year period of study.
At Least a Trace of Snow Cover Reported at Fort Wayne
|Percentage of years
at least a Trace
|Inclusive Dates Various
Reported Without Break
|10 percent||Nov. 13 through Mar. 28|
|20 percent||Nov. 24 through Mar. 23|
|25 percent||Nov. 27 through Mar. 21|
|30 percent||Dec. 09 through Mar. 16|
|40 percent||Dec. 10 through Mar. 04|
|50 percent||Dec. 16 through Feb. 23|
|60 percent||Jan. 02 through Feb. 17|
|70 percent||Jan. 25 through Jan. 31|
|75 percent||Jan. 28 through Jan. 29|
A. Dates of Earliest and Latest Occurrences of Various Amounts of Snow Cover
Although snow cover is most common at Fort Wayne from mid-December through early-March, snow on the ground is occasionally reported as early as mid-autumn and as late as mid-spring. These relatively early and late reports are usually the result of snowstorms that dump snowfall amounts that are more common during mid-winter. The earliest occurrence of at least 1 inch of snow cover resulted from a snowstorm that deposited 8.0 inches of snow on October 19-20, 1989.
The latest occurrence of at least 5 inches of snow cover was the result of two snow storms in early-April 1982. The first storm dropped 5.4 inches of snow over a three-day period (April 4-6). Five inches of snow cover was reported on April 6. Before that snow cover melted away, a second snowstorm moved through the area, depositing 4.4 inches of snowfall at Fort Wayne over another three-day period (April 8-10). This snowfall, added to the 2 inches of snow cover on April 8, resulted in six inches of snow cover being reported on April 9.
Table 2 lists the earliest and latest occurrences of various snow cover amounts from 1920-21 through 1998-99 at Fort Wayne.
Dates of Earliest and Latest Occurrence of Various Snow Cover Amounts
at Fort Wayne, Indiana
|Date of Earliest
|Date of Latest
|At least a Trace||Oct. 18, 1972||Apr. 25, 1968|
|At least 1 inch||Oct. 19, 1989||Apr. 13, 1950|
|At least 5 inches||Nov. 03, 1966||Apr. 09, 1982|
|At least 10 inches||Dec. 09, 1977||Mar. 12, 1964|
|At least 15 inches||Dec. 09, 1977||Feb. 23, 1978|
|At least 20 inches||Feb. 09, 1982||Feb. 09, 1982|
B. Average Seasonal Snow Cover per 5-year and 10-year Periods
As mentioned, yearly snowfall totals at Fort Wayne have varied since records have been kept. A similar pattern shows up in statistics for snow cover. Years with relatively large amounts of snowfall have also tended to record large numbers of days with snow cover. Conversely, years with less snowfall have usually shown fewer numbers of days with snow cover.
Table 3 below lists the seasonal average number of days that various snow cover amounts have been reported during 5-year periods. Table 4 shows the same statistics for 10-year periods. The 1940s through the 1970s averaged relatively large seasonal totals of days with snow cover of a trace or more, 1 inch or more, and 5 inches or more. This correlates to the increasing trend of larger yearly snowfall totals from the 1950s through the 1970s. During other decades with less average snowfall, some seasons recorded large numbers of days with snow cover, such as 1944-45 and 1981-82. These two seasons not only reported large snowfall totals but were also colder than average.
The years of the late-1920s averaged almost 75 days of snow cover per year. However, this was mostly shallow snow cover. These five years only averaged four days of snow cover of 5 inches or greater. The snowy years of the late-1970s and early-1980s clearly stand out in the data. These ten years are the only ones that averaged approximately two months of snow cover of 1 inch or greater per season. They are also the only years to average over20 days of snow cover of 5 inches or more per season.
Average Number of Days Various Snow Cover Amounts
were Reported During a Season
|1920-21 through 1923-24*||64.3||31.3||6.0|
|1924-25 through 1928-29||74.0||38.6||4.0|
|1929-30 through 1933-34||56.6||27.2||5.4|
|1934-35 through 1938-39||66.6||35.6||5.4|
|1939-40 through 1943-44||77.4||30.8||7.2|
|1944-45 through 1948-49||67.6||42.2||9.2|
|1949-50 through 1953-54||64.8||30.8||6.4|
|1954-55 through 1958-59||76.4||38.6||1.6|
|1959-60 through 1963-64||83.6||45.2||9.0|
|1964-65 through 1968-69||76.0||35.2||4.6|
|1969-70 through 1973-74||71.0||36.4||5.8|
|1974-75 through 1978-79||89.8||64.8||24.6|
|1979-80 through 1983-84||78.2||55.0||20.4|
|1984-85 through 1988-89||57.2||36.6||11.6|
|1989-90 through 1993-94||60.4||38.0||5.8|
|1994-95 through 1998-99||52.8||31.2||12.8|
|* only four years of data|
|1920-21 through 1928-29*||69.7||35.3||4.9|
|1929-30 through 1938-39||61.6||31.4||5.4|
|1939-40 through 1948-49||72.5||36.5||8.2|
|1949-50 through 1958-59||70.6||34.7||4.0|
|1959-60 through 1968-69||79.8||40.2||6.8|
|1969-70 through 1978-79||80.4||50.6||15.2|
|1979-80 through 1988-89||67.7||45.8||16.0|
|1989-90 through 1998-99||56.6||34.6||9.3|
|* only nine years of data|
C. Yearly Comparison of Snow Cover
In looking at the yearly snow cover data for the past 79 winter seasons, it can clearly be seen some years have more snow cover than other years. Years during which large amounts of snow fell, i.e., 1981-82, 1977-78, and 1983-84 also record large numbers of days in which snow cover was reported. Many of these large snowfalls could accompany the passage of cold fronts which usher in very cold air which would cause the snow cover to last that much longer. The snow cover, in turn, would help to modify the overlying air mass, cooling it even more and allowing it to last longer. This feedback mechanism has no doubt contributed to very cold outbreaks, one of the most notable, the incredible cold outbreak that affected the eastern two-thirds of the United States in mid-February 1899.
It was estimated that day time maximum temperatures during January 1984 in parts of the Midwest were 9°F cooler than expected from atmospheric conditions. Extensive snow cover built up during a record cold spell in December 1983 helped prolong wintry weather (Burroughs 1999).
Figure 3 depicts the winter seasons at Fort Wayne during the last 79 years with the largest number of days with snow cover of a trace or more. Figure 4 lists the seasons with the fewest number of days with snow cover of a trace or more.
The four winter seasons (Figure 3) are reported snow cover on more than 100 days were also years that recorded relatively large snowfall totals and were also colder than normal. Two of these winters were the snowiest on record at Fort Wayne. During the winter of 1981-82, a total of 81.2 inches of snowfall was reported. The second-highest total was recorded in 1977-78 when 60.6 inches of snow fell. The large amount of snowfall, along with the colder than normal temperatures, certainly helped the snow cover to remain as long as it did during these two incredible winters.
Figure 3. Winters with most days of snow cover observed at Fort Wayne, Indiana. Number of days having snow cover is given to the right of bar for each winter.
Figure 4. Same as Figure 3, but for winters with fewest days of snow cover observed at Fort Wayne, Indiana.
The 1925-26 season was not particularly snowy, but snowfall was reported from autumn through early-spring. Almost 1 ½ inches of snow fell in October 1925. During the first four months of 1926, snowfall was fairly equally distributed. A total of 6.8 inches fell in April alone. The wide distribution of snowfall throughout the winter allowed snow cover to be reported from October through April. In addition, 1983-84, 1966-67, and 1950-51 were among the top ten snowiest winters in Fort Wayne.
Many of the winters with the least snow cover had smaller than average snowfall totals or were warmer than average. During the winter of 1931-32, for example, only 8.3 inches of snow fell. The winter was also warmer than normal. In fact, the only month that had an average temperature below freezing was March 1932, which had a monthly average of 29.8°F.
The 1948-49 season only recorded 15.2 inches of snowfall. The 1997-98 season also received relatively little snow, only recording 13.9 inches. In fact, no snowfall was reported during the entire month of February 1998 (the only February on record at Fort Wayne not to receive any snowfall). The fairly dry and warm late-1980s and 1990s show up very well in the statistics.
Figures 5 and 6 show the years with the most days with 1 inch or greater of snow cover and 5 inches or greater of snow cover, respectively. It's interesting to note that just because a winter season has a large number of days with a trace or more of snow cover reported, it may not have much deeper snow. For example, the 1925-26 snowfall season had 107 days during which at least a trace of snow cover was reported. However, on only 45 of those days was there 1 inch or greater of snow cover, and on no day was there 5 inches or more. Four inches was reported on only two days.
Similarly, during the 1939-40 season a trace or more of snow cover was reported on 101 days (more than three months). But 1 inch or greater of snow cover was reported on only 48 days, and daily snow cover of 5 inches was reported only once.
Figure 5. Winters with most days having a snow depth or one inch or greater at Fort Wayne, Indiana. Number of days with at least one inch snow depth observed is given to right of bar for each winter.
Figure 6. Same as Figure 5, but for winters with the most days of five inches or greater snow depth.
An opposite situation occurred during the 1944-45 season. Snow cover of any depth was reported on 87 days, the 15thlargest seasonal total during the 79 year period. But much of this was relatively deep snow. Of this total, 1 inch or more was reported on 71 days (82 percent of the total number of days with snow cover). Five inches or more of snow cover was reported on 46 days (53 percent of the total). During one stretch of 25 days (Dec. 25 - Jan. 18) the daily snow cover never dropped below 5 inches.
D. Periods of Continuous Snow Cover
Winters that experience fairly heavy snowfall and colder than normal temperatures can see snow cover totals grow. Residents of the southern Great Lakes region have experienced a wide variety of winter snowfall totals. Some years have been relatively dry. As mentioned, this was a common pattern during the 1920s, 1930s, and 1940s. Annual snowfall totals for these decades were relatively low. This is the case for not only Fort Wayne but at other observation locations across the southern Great Lakes region.
Larger average snowfall amounts were reported in many winters starting in the 1950s and continuing to the present. During the late-1950s to early-1960s, and again during the late-1970s to early-1980s, the southern Great Lakes region experienced many winters with relatively large annual snowfall totals. When very cold air was in place snow cover could last continuously for a couple of months or longer. Table 5 is a chronological list of some winter periods during which snow cover lasted for 50 days or longer at Fort Wayne.
Some Notable Periods of Continuous Snow Cover
(of at least a trace) Fort Wayne, Indiana
|Inclusive Dates||Length of Time
|Dec. 25, 1926 - Feb. 15, 1927||53|
|Dec. 15, 1935 - Mar. 02, 1936||79|
|Dec. 20, 1939 - Mar. 17, 1940||89|
|Dec. 10, 1944 - Feb. 23, 1945||76|
|Dec. 15, 1947 - Feb. 16, 1948||64|
|Nov. 21, 1950 - Jan. 18, 1951||59|
|Dec. 25, 1975 - Feb. 12, 1976||50|
|Dec. 21, 1976 - Feb. 23, 1977||65|
|Dec. 03, 1977 - Dec.17, 1977||(15)||108 total|
|(Dec. 18 - 20 no snow cover was reported)||(3)||(Deep snow cover,
15 to 17 inches)
|Dec. 21, 1977 - Mar. 20, 1978||(90)|
|Jan. 02, 1979 - Mar. 03, 1979||61|
(10 to 13 inches of snow cover)
|Dec. 19, 1980 - Feb. 18, 1981||62|
|Dec. 17, 1981 - Mar. 15, 1982||89|
|(Very deep snow cover. Record depth of 20" on Feb. 9)|
|Dec. 15, 1983 - Feb. 12, 1984||60|
Table 6 lists the longest periods of time that various snow cover amounts have been reported on consecutive days. The inclusive dates are also listed.
Longest Periods of Snow Cover of Various Amounts
(Fort Wayne, Indiana)
|Trace or more||90||Dec. 21, 1977 - Mar. 20, 1978|
|89||Dec. 20, 1939 - Mar. 17, 1940|
|89||Dec. 17, 1981 - Mar. 15, 1982|
|79||Dec. 15, 1935 - Mar. 02, 1936|
|76||Dec. 10, 1944 - Feb. 23, 1945|
|65||Dec. 21, 1976 - Feb. 23, 1977|
|64||Dec. 15, 1947 - Feb. 16, 1948|
|62||Dec. 19, 1980 - Feb. 18, 1981|
|61||Jan. 02, 1979 - Mar. 03, 1979|
|60||Dec. 15, 1983 - Feb. 12, 1984|
|59||Nov. 21, 1950 - Jan. 18, 1951|
|53||Dec. 25, 1926 - Feb. 15, 1927|
|51||Dec. 19, 1924 - Feb. 07, 1925|
|51||Jan. 13, 1939 - Mar. 04, 1939|
|50||Dec. 25, 1975 - Feb. 12, 1976|
|1 inch or more||69||Jan. 09, 1978 - Mar. 18, 1978|
|67||Dec. 10, 1944 - Feb. 14, 1945|
|65||Jan. 07, 1982 - Mar. 12, 1982|
|57||Jan. 06, 1979 - Mar. 03, 1979|
|56||Dec. 27, 1976 - Feb. 20, 1977|
|52||Dec. 21, 1983 - Feb. 10, 1984|
|45||Jan. 10, 1985 - Feb. 23, 1985|
|40||Jan. 16, 1936 - Feb. 24, 1936|
|37||Dec. 23, 1969 - Jan. 28, 1970|
|36||Dec. 25, 1926 - Jan. 29, 1927|
|35||Jan. 07, 1976 - Feb. 10, 1976|
|5 inches or more||54||Jan. 17, 1978 - Mar. 11, 1978|
|26||Jan. 28, 1979 - Feb. 22, 1979|
|25||Dec. 25, 1944 - Jan. 18, 1945|
|23||Feb. 01, 1982 - Feb. 23, 1982|
|18||Jan. 07, 1981 - Jan. 24, 1981|
|18||Feb. 05, 1985 - Feb. 22, 1985|
|16||Jan. 17, 1985 - Feb. 01,1985|
|15||Jan. 03, 1996 - Jan. 17, 1996|
|14||Dec. 18, 1929 - Dec. 31, 1929|
|14||Jan. 28, 1977 - Feb. 10, 1977|
|10 inches or more||34||Jan. 26, 1978 - Feb. 28, 1978|
|16||Feb. 01, 1982 - Feb. 16, 1982|
|9||Feb. 12, 1979 - Feb. 20, 1979|
|6||Feb. 13, 1985 - Feb. 18, 1985|
|5||Dec. 20, 1973 - Dec. 24, 1973|
|15 inches or more||29||Jan. 26, 1978 - Feb. 23, 1978|
|12||Feb. 04, 1982 - Feb. 15, 1982|
|20 inches or more||1||Feb. 09, 1982 (20 inches)|
E. Yearly Comparison of Snow Cover
To make the comparison of Winters as objective as possible, the Snow Cover Inch-Day Index (SCIDI) was developed. In this index, successively larger amounts of snow cover during a season are assigned increasingly larger weights. For example, each day with 1 inch of snow cover is given a weight of one. Each day with snow cover of 2 inches is given a weight of two, 5 inches is given a weight of five, etc. Each day with a trace of snow cover is given a weight of 0.5.
In calculating the SCIDI for the 1978-79 winter season, for example, the total number of days with a trace of snow cover (27 days) was multiplied by 0.5, giving 13.5. The number of days with 1 inch of snow cover (15) was multiplied by 1, giving 15. The total number of days with 5 inches of snow cover (4) was multiplied by a factor of 5, giving a total of 20. The number of days with 10 inches of snow cover reported (5) was multiplied by 10, resulting in 50. The largest snow cover reported during the season was 13 inches. It occurred only once so 13 was multiplied by 1, giving a total of 13. The SCIDI calculations for each of the various snow cover amounts during the season (trace, 1 inch, 2, 3, 4, 5, 6, etc.) add up to the total SCIDI of 313.5. The total calculation for the 1978-79 season is illustrated below.
Fort Wayne, Indiana Snow Cover
|Days of snow cover||27||15||6||6||2||4||3||9||6||0||5||1||2||1|
The SCIDI allows for a more objective comparison of snow cover recorded at an observation site. This is especially true for locations that receive fairly substantial snowfall totals (such as the upper Mississippi valley, Great Lakes region, and northeastern U.S.). At other locations that receive little or no snowfall it may not be as appropriate since it only uses snow cover in its calculation.
Table 7 lists the 39 snowfall seasons at Fort Wayne during which the most snow cover was recorded. Table 8 lists the 40 snowfall seasons that recorded the least amount of total snow cover. The seasons during the last 79 years that experienced the greatest amounts of annual snow cover also tended to be some of the snowiest and coldest winters during this same period. The winter seasons of 1981-82, 1977-78, and 1983-84 are three of the four snowiest on record (1911-12 being third). These years were not just snowy across the Great Lakes region. In late-January 1978, for example, snow cover of 1 inch or more was reported as far south as the Tennessee River valley and central Arkansas (Ludlum 1979). As mentioned, the large snowfall amounts and resulting snow cover may have contributed to the colder than normal temperatures, and then the cold temperatures could have allowed the snow cover to remain even longer.
Most Snow Cover in Fort Wayne
|(1920-21 through 1998-99)|
Least Snow Cover in Fort Wayne
(1920-21 through 1998-99)
|SCIDI||Trace or more||1 inch or more||5 inches