Contact:  Randee Exler                    FOR IMMEDIATE RELEASE
                                          May 1, 1997

The National Weather Service issued a special report today evaluating a reported lake-effect snowfall record for Jan. 11-12, 1997, in Montague, N.Y. Citing differences between operational and climatological measurements, the NWS ruled that the reported 77-inch, 24-hour snowfall is not a new national climatological record.

"There is no doubt that this was an extremely large storm and the snow measurements provided by a local volunteer snow spotter contributed greatly to the Buffalo forecast office's real-time operations for this event," said Robert J. Leffler, a physical scientist in the NWS's Office of Meteorology and team leader of the weather and climate experts who assessed the storm. "However, the operational snowfall measurements taken by the volunteer snow spotter were too frequent for the 77-inch total to be recognized as an official national, climatological record."

The procedures for making the climatological snowfall observations that are the basis for records are different than routine operational measurements, because climatological measurements are taken less often. Official climatic observations limit the frequency of snowfall measurements to a maximum of one per every six hours. Climatic observations are then added together to determine 24-hour totals in accordance with NWS Standards, Guidelines and Measurements of Snowfall. More frequent measurements tend to increase totals, especially during low density (fluffy) snows such as the one Montague experienced during the Jan. 11-12 period. This is because the more frequently snow is measured and removed from the observation surface, the less settling is included in the measurement.

Weather service forecast offices use operational observations, such as those provided by the Montague snow spotter, to improve local snowfall forecasts and warnings and improve radar estimates. Operational observations can be taken as frequently as hourly. For this event, the volunteer observer took six valid operational observations within a 24-hour period, which when added together totaled 77 inches.

"We commend the volunteer observer for supporting the local NWS Buffalo forecast office's operational mission under such difficult conditions," Leffler said. "The fact that the committee recommends not to accept the snowfall total as an official climatological record neither diminishes this volunteer's credibility, nor reduces the usefulness of these measurements. In any case, the committee validated the accuracy of the individual observations and found the observer to be exceptionally diligent."

In the report, the committee states that there is an urgent need to ensure that NWS offices and observers understand the difference between climatological and operational observations, and that they adhere to appropriate procedures to maintain the integrity of the nation's climate records. To reach this goal, the committee recommends that training materials and equipment such as snow boards (square white board with at least 18-inch sides on which snow is measured) be made available to all observers to use.

The Committee also recommends that the National Oceanic and Atmospheric Administration, the NWS's parent agency, create a committee responsible for assessing new national weather and climate records.

Silver Lake, Colo., currently holds the record for the most snow in a 24-hour period with 76-inches accumulating from April 14-15, 1921. The Silver Lake measurement was analyzed and accepted as a climatological record by the NWS in a peer-reviewed journal in 1953.

Note to Editors:

This report can be accessed electronically at the following Internet address: http://www.nws.noaa.gov/om/snowpln.htm In addition to findings and recommendations, the report includes the NWS Standards, Guidelines, and Measurement of Snowfall.