Abstract
Heavy snowfall has occurred in northwest Missouri on at least one occasion during every month from October through April. A study to investigate the climatology of heavy snowfall in this region, which is the forecast area for the National Weather Service Office in Pleasant Hill, Missouri was conducted by the office in cooperation with the Atmospheric Sciences Program at the University of Missouri-Columbia. In addition to the climatological study, a goal of the project was to investigate both the synoptic and dynamic aspects of heavy snow producing winter storms for northwest Missouri.
Preliminary results of the investigation show that there are four general synoptic patterns conducive of heavy snowfall for northwest Missouri. The patterns are 1) the southwest U.S. low, 2) progressive short wave trough, 3) northwest flow system and 4) deepening low. These patterns were further dissected synoptically and dynamically in an attempt to reveal the specific lifting mechanisms so that an ingredients based model for snow forecasting could be developed for the Pleasant Hill forecast office. The kinematic and geostrophic gridded fields for this inquiry were investigated using the NCEP Reanalysis.
In addition to the spatial investigation of synoptic and dynamic features, a temporal study of the historical systems revealed that the heavy snowfall events usually occurred in a period of 24 hours or more. Distinct synoptic and dynamic vertical motion producing parameters were identified at the forward motion side of the storm and also on the rear or exiting portion of the storm.
This paper will discuss the synoptic and dynamic parameters found in each of the four aforementioned synoptic patterns as well as their temporal and spatial relationship to the heavy snowfall. The frequency of heavy snowfall as well as the most prominent time of the cold season for the occurrence of each individual pattern will also be discussed.
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