David A. Robinson
A major lake effect snow event struck areas downwind of Lakes Erie and Ontario between January 10-14, 1997. During a 24-hour period on the 11th and 12th, a National Weather Service (NWS) snow spotter at Montague, NY, located on the Tug Hill Plateau just east of Lake Ontario, reported six measurements of snowfall, which when summed, totaled 77 inches. If accepted as a valid total, this would surpass the previous national 24-hour snowfall record of 76", observed at Silver Lake, CO on April 14-15, 1921.
Shortly after the event, the NWS assembled a committee of snow experts from academic and government communities to investigate the Montague observation. This involved a field trip to the Tug Hill region to interview the Montague observer, several other snow spotters, local authorities and snow removal crews. It also included climatologic analyses of this and earlier lake effect events, and an evaluation of snow measurement standards. The team also evaluated the Silver Lake event, however it was not the mission of the committee to verify or refute the Colorado observation.
Following careful evaluation and deliberation, the committee recommended that the 77" total not be recognized as a national record. While the six observations during the 24 hour interval were made in a valid scientific manner, thus providing valuable support for real-time NWS operations, they were taken at intervals too frequent to qualify as a vaild 24 hour observation. NWS standards require that no more than four observations, taken with a maximum frequency of once every six hours, be summed within any 24-hour period to compute the total snowfall for that period. More frequent measurements, accompanied by clearing the snow board following each observation, tend to increase totals. This is especially true for lake effect events, when snow densities are often quite low, as was the case in the January 1997 storm.
The committee felt strongly that the legacy of this investigation should not just be the evaluation of this single event. Therefore, they took the opportunity in the study report (NWS Special Report, March 1997) to recommend that, 1) the NWS should insure training materials and snow boards be made available and placed in use at all observing stations, and 2) that the National Climatic Data Center take the lead in establishing a committee that would be responsible for assessing observations submitted as national meteorological/climatological extreme values. The latter has been established, and recently evaluated, and subsequently refuted, a reported world-record wind gust on Guam last Fall.
Observations of snow made by volunteer observers are crucial for real- time NWS operations, as well as for insuring a lengthy climatologic data base. This is particularly true at present, when snow observations have been reduced or eliminated at many first-order NWS stations. However, to maintain the integrity of climatic records, thus permitting comparisons and analyses to be made over time at individual stations and between stations, established snow measurement standards must be followed. It is the responsibility of the National Weather Service to educate and equip observers, and the responsibility of the observers to follow standard observing procedures.