NWC REU 1998



Climatology of Warm Season Morning Precipitation Systems and Their Environments

Jill Derby, Carl Hane, and David Andra



A minimum of thunderstorm activity has been observed during the late morning hours in the Great Plains region. This minimum is the result of dissipation of nocturnal activity slightly earlier in the day and development of new activity in the early afternoon. This time period is of particular interest to forecasters because of uncertainty in whether systems will survive or dissipate. A climatological study has been done for 8 summer months during morning hours within the Norman, OK and Dodge City, KS forecast areas. A total of 181 precipitation systems that occurred on 127 days were identified based upon archived hourly precipiation data. The track of each system was determined and statistics on direction of motion compiled. Comparisons between system motion and direction of 500 mb flow were made. A limited assessment of the importance of surface fronts and troughs was carried out. The evolution of each system was noted for both the data set as a whole and individual flow regions, and the tendency for system dissipation during this period of the day was confirmed.

Paper available upon request.