To more accurately forecast hail size in conjunction
with thunderstorms along the Gulf Coast or in any air
mass where the Wet-Bulb-Zero height is above 10,500
feet, it is necessary to refer to the graph in figure 5-11.
The hail size derived from figure 5-10 is entered on the
horizontal coordinate of figure 5-11, and the corrected
hail size read off is compatible with the height of the
A Thunderstorm Checklist
Regardless of where you are forecasting, the factors
and parameters favorable for thunderstorm, hail, and
gust forecasting should be systematized into some sort
of checklist to determine the likelihood and probability
of thunderstorms and the attendant weather. Figure
5-12 is a suggested format and checklist to ensure that
all parameters have been given due consideration.
LEARNING OBJECTIVES: Analyze areas
conducive to tornadic activity. Identify the
three general types of tornadoes. Recognize the
difference between tornadoes and waterspouts.
Tornadoes are violently rotating columns of air
extending downward from a cumulonimbus cloud.
They are nearly always observed as funnel clouds.
Their relatively small size ranks them as second in the
severity of the damage they cause, with tropical
cyclones ranking first. They occur only in certain areas
of the world, and are most frequent in the United States
in the area bounded by the Rockies to the west and the
Appalachians to the east. Tornadoes also occur during
certain preferred seasons of the year in the United States,
Figure 5-11.-Hail size at surface expected from tropical air mass thunderstorm.