The Kansas City Severe Weather Event of 4 June 1979

Abstract

The severe weather and localized flooding which hit Kansas City on the afternoon of 4 June 1979 are investigated through a detailed synoptic scale and mesoscale analysis of the events leading up to the formation of the storms. The results indicate that despite a middle and upper troposphere characterized by weak synoptic scale forcing and an absence of many of the ?classic? severe weather parameters, a line of deep convection developed from north central Kansas through northwest Missouri and into southern lowa. The key feature was to be found in the lower troposphere in the form of a trough line which had formed along the lee side of the Rocky Mountains and moved eastward into the Great Plains area with the approach of an upper level shortwave from the northwest. Convergence and southwesterly flow ahead of the low-level trough helped create a thermodynamically favorable environment, while the associated ascent provided the necessary lift to ignite the convection. The most intense cells were confined to a small area in extreme northwest Missouri and formed in response to the intersection of the trough line with air behind an old outflow boundary which contained high values of equivalent potential temperature. In several respects the storm was not well forecast which partially can be attributed to the failure of the operational Limited Area Fine Mesh quantitative precipitation forecasts which generated no precipitation in an area where flash flooding later occurred. The storm was an example of a northwest flow severe weather event. Our findings are compared and contrasted with the published northwest flow severe weather climatology by Johns.