In the mature and most intense stage of a thunderstorm, the water
droplets within the cloud collide and combine to form rain and hail and, at
cooler temperatures, sleet and snow. This stage poses many hazards to
aircraft including heavy precipitation, high winds, convective wind shear,
severe turbulence, downbursts, hail, icing, tornadoes, and lightning.
In the dissipating stage, the updraft weakens and at the same time, the
convective wind shear and other hazardous conditions begin to subside.
There may be high rainfall rates in this stage, but the severe dangers are
THE WX-500 AND WEATHER RADAR
The storm mapping technology used in the WX-500 system is fundamen-
tally different than the technology used in weather radar. Weather radar
operates by transmitting UHF radio waves in the direction of interest and
then receiving echoes from water droplets, whereas the WX-500 oper-
ates by receiving signals already present in the atmosphere due to elec-
trical discharges. The WX-500 analyses the unique characteristics of
these signals, their signal strength, and their varying rates of recurrence
to determine the location and intensity of the thunderstorms that gener-
ated the discharges. The WX-500 can receive radiated electromagnetic
signals from electrical discharges up to 200 nm away.
The cumulus stage of a thunderstorm (usually precipitation free) is
unlikely to appear on weather radar; however, it generally does contain
electrical discharges that will be detected by the WX-500 and will appear
on the KMD 150's Stormscope display as a light but increasing cluster of
The WX-500 is not subject to attenuation. Weather radar, however, is
subject to attenuation and may not see the "storm behind the storm" or
may understate its intensity. With the WX-500, electrical discharges are
mapped throughout the storm area. The size of the cluster of discharge
points displayed on your KMD 150 Stormscope screen indicates the size
of the storm area. The speed with which the discharge points appear
indicate the intensity of the storm regardless of the size of the cluster.
The more intense the storm, the faster the discharge points appear.
Rev 1 Mar/2000
KMD 150 Pilot's Guide