Severe Storm Reports: April-September, 1989-1998

Fig. 1. The frequency of severe storm reports across the contiguous United States, normalized per 10,000 km^2 per warm season. Data from April through September from 1989 - 1998 were included in this study.


PPCG Severe Storm Reports: April-September, 1989-1998

Fig. 2. The frequency of severe storm reports that are accompanied by predominately positive cloud-to-ground (PPCG) lightning (> 50% +CG). The frequency is normalized per 10,000 km^2 per warm season (1989-1998).

% of Severe Storm Reports dominated by +CG: April-September, 1989-1998

Fig. 3. The percentage of severe storm reports that are accompanied by predominately positive cloud-to-ground (PPCG) lightning (> 50% +CG) for the 1989-1998 warm seasons.

HFD PPCG Severe Storm Reports: April-September, 1989-1998

Fig. 4. The frequency of severe storm reports that are accompanied by high flash density (HFD, > 0.01 km-2 h-1) predominately positive cloud-to-ground (PPCG) lightning (> 50% +CG). The frequency is normalized per 10,000 km^2 per warm season (1989-1998).

% of Severe Storm Reports dominated by HFD +CG: April-September, 1989-1998

Fig. 5. The percentage of severe storm reports that are accompanied by high flash density (HFD, > 0.01 km-2 h-1) predominately positive cloud-to-ground (PPCG) lightning (> 50% +CG) for the 1989-1998 warm seasons.

Severe Storm Days: April-September, 1989-1998

Fig, 6. The color shading denotes the mean number of severe storm (large hail and tornado) days per 10,000 km^2 per warm season from 1989-1998. The contours represent the number of severe storm days characterized by predominately positive cloud-to-ground (PPCG) lightning (i.e., > 50% +CG lightning). Contours are displayed for 1, 3, 5, and 7 days. Although severe storm days occur with moderate frequency (e.g., > 2 days per 10,000 km^2 per warm season) all across the eastern 2/3 of the country, severe storm days with > 50% PPCG lightning occur primarily in the High Plains and upper Midwest. The overall maximum of > 7 days occurs in western Kansas. The proposed STEPS experiment falls within the northern portion of this frequency maximum of +CG severe storm days.


Please direct any questions, comments, or suggestions to Larry Carey at carey@olympic.atmos.colostate.edu