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