Updated 29 August 2003.  Comments to Harold Brooks)


What is the annual cycle of severe thunderstorms in the United States?

Animations

The following animated loops show the annual cycle of severe weather threats through the year.  Each frame shows the climatological probability of the event occurring within 25 miles of any point for that day.  Each loop begins on 1 January a frame every 7 days.  The dates at the bottom of the images are given by the form YYMMDD/0000, where MM is the month and DD is the day of the month.  (The YY is extraneous).  The probabilities for all severe weather and for "high-end" non-tornadic weather are in per cent.  The significant tornado (F2 or greater) loops have contours in hundredths of a per cent and the violent tornado (F4 or greater) loops are in thousandths of a per cent.  Bold links indicate Java animations with speed controls.

All Severe Weather

Probability Of Any Severe Weather For 1980-1994 (Java Applet)

Period

Any Tornado

Hail (3/4 inch diam. or greater or damaging) 

Thunderstorm winds (50 kts or greater or damaging)
1980-1999
(all 20 yrs.)		 Java applet Java applet Java applet
1980-1984 Looping gif Looping gif Looping gif
1985-1989 Looping gif Looping gif Looping gif
1990-1994 Java applet Java applet Java applet
1995-1999 Java applet Java applet Java applet

Click here to see individual frames from "All Severe Weather" loops above.

"High-End" Severe Weather

Period

Significant Tornado (F2 or greater) 

Violent Tornado (F4 or greater)

Hail (2 inch diam. or greater)

Thunderstorm winds (65 kts or greater) 
1921-1995
Java applet
Java applet
1951-1965
Java applet
1980-1994
Java applet
Java applet


Click here to see individual frames from "High-End Severe Weather" loops above.

Back to Thunderstorm Hazards page