Weather Radio User Manual

PRIMUS
r
880
Digital
W
eather
Radar
System
A28-1146-102-00
Radar Facts
5-41
Althoughpenetratingastormwithared(level three) coreappears tobe
an acceptable risk, it is not. At the lower end of the red zone, there is
nochanceofextremeturbulence,aslightchanceof severeturbulence,
and a 40% chance of moderate turbulence. However, the radar lumps
alloftherainfallratesbetween12mm to50mmperhourintoonegroup
- a level three (red). Once the rainfall rate reaches the red threshold,
it masks any additional information about the rainfall rate until the
magenta threshold is reached. A red return covers a range of
turbulence probabilities and the worst case must be assumed,
especiallysinceextreme,destructiveturbulenceisbornintheredzone.
Therefore, once the red threshold is reached, the risk in penetration
becomes totally unacceptable.
Likewise, once the magenta threshold is reached, it must be
assumed that more severe weather is being masked.
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
TURBULENCE PROBABILITY
LIGHT
LEVEL 1
GREEN
LEVEL 2
YELLOW
LEVEL 3
RED
LEVEL 4
MAGENTA
(4 mm / Hr) (12 mm / Hr) (50 mm / Hr)
AD-15357-R2@
RAINFALL RATE
Probability of Turbulence Presence
in a Weather Target
Figure 5-29