A World of Weather: Chapter 10 Laboratory Question

Chapter 10

7. On the evening of April 26, 1991, a powerful F5 tornado struck Andover, KS, just northeast of Wichita. This F5 tornado was part of a 55-tornado outbreak across six states stretching from northeastern Texas into Iowa. In Figure 10.24 you are given weather data at 00Z on April 27, 1991. Figure 10.24a shows 500-mb heights (in dekameters), Figure 10.24b shows surface winds speeds (in knots), and Figure 10.24c shows 850-mb wind speeds (in knots). Figure 10.24d shows the temperature and dew point (both in °C) through the lower troposphere at Topeka, an upper-air station in northeast Kansas.

  1. Isopleth the 500-mb height in Figure 10.24a at intervals of 60 meters (start with the 5700-meter contour). Remember that "570" represents 5700 meters. Indicate any troughs with a heavy dark line. What characteristics of the 500-mb pattern favor severe thunderstorms in Kansas around this time?
  2. On Figure 10.24c, draw the 50-knot isotach. Shade in the areas where the wind speed is greater than 50 knots, thereby isolating the fastest winds at this level. For each upper-air station, compute the difference in wind speed between the 850-mb level and the surface. In which state is the speed vertical wind shear the largest?
  3. What characteristics of the temperature and moisture profile of the lower troposphere favored tornado formation in eastern Kansas around this time?