Fig. 1. (a) The total number of derechos identified during the warm season (May-Aug.), 1980-83 by JH87. (b) The total number of derechos identified during the warm season, 1986-95 by BM98 (from BM98).

Fig. 2. A mapping of severe wind reports from 2200 UTC 11 August 2000 to 0830 UTC 12 August 2000 in the northern Plains region. The location of each report is indicated by a "+". The times (UTC) of selected reports and descriptions of the associated convective structures are indicated on the figure.

Fig. 3. The distribution of warm-season (May-Aug.) derechos for, (a) all 168 events, (b) the 70 events from 1986-95, and (d) the 98 events from 1996-2001. Contours are drawn every 5 events in all panels. In all panels (and subsequent figures), the sequence of shading from dots (.) to lines (-) to hatching (+) encloses the third, fourth, and fifth contour levels, respectively.

Fig. 4. The distribution of derechos for the months of Sep.-Apr. for (a) all 76 events from 1986-2001, (b) the 26 events from 1986-95, and (d) the 50 events from 1996-2001. Contours are drawn every 4 events in all panels.

Fig. 5. The distribution of warm-season derechos from 1986-2001 for (a) the 55 low-end events, (b) the 82 moderate events, and (c) the 31 high-end events.

Fig. 6. The percentage (%) of the total number of warm season events accounted for by the low-end events. Only the percentages for those locations with at least 10 total events are shown. Contours are drawn every 10% starting at 30%.

Fig. 7. The distribution of warm-season, low-end derechos from (a) 1986-1995 (21 events), and (b) 1996-2001 (34 events). Contours are drawn every 2 events in both panels.

Fig. 8. The distribution of warm season, moderate & high-end derechos from (a) 1986-2001 (113 events), (b) 1986-95 (49 events), and (c) 1996-2001 (64 events). Contours are drawn every 4 events in all panels.

Fig. 9. The distribution of derechos for the months of Sep.-Apr. from 1986-2001 for the (a) 18 low-end events, (b) the 34 moderate events, and (c) the 24 high-end events. Contours are drawn every 2 events in all panels.