12-41
190-01007-03 Rev. Q
GTN 725/750 Pilot’s Guide
Foreword
Getting
Started
Audio &
Xpdr Ctrl
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FPL
Direct-To
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Wpt Info
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Nearest
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Appendix
Index
12.3.5 Weather Mapping and Interpretation
12.3.5.1 Weather display Interpretation
When evaluating various target returns on the weather radar display, the
colors denote approximate rainfall intensity and rates as shown in the table
below.
Weather
Mode
Color
GWX 68 Radars
GWX 70 Radars
3rd Party
Radars
Approximate
Intensity
Approximate
Rainfall Rate
(in/hr)
Approximate
Intensity
Radar Return
Level (see
radar docu-
mentation
for details)
BLACK
< 23 dBZ
< .01
< 23 dBZ
0
GREEN
23 dBZ to < 33 dBZ
.01 - 0.1
23 dBZ to < 33 dBZ
1
YELLOW
33 dBZ to < 41 dBZ
0.1 - 0.5
33 dBZ to < 41 dBZ
2
RED
41 dBZ to < 50 dBZ
0.5 - 2
41 dBZ to < 49 dBZ
3
MAGENTA
50 dBZ and greater
> 2
> 49 dBZ
4
Table 12-29 Precipitation Intensity Levels
12.3.5.2 Thunderstorms
Updrafts and downdrafts in thunderstorms carry water through the cloud.
The more severe the drafts, the greater the number and size of the precipitation
droplets. With this in mind, the following interpretations can be made from what
is displayed on the weather radar. Avoid these areas by an extra wide margin.
• In areas where the displayed target intensity is red or magenta (indicating
large amounts of precipitation), the turbulence is considered severe.
• Areas that show steep color gradients (intense color changes) over thin bands
or short distances suggest irregular rainfall rate and strong turbulence.
• Areas that show red or magenta are associated with hail or turbulence, as
well as heavy precipitation. Vertical scanning and antenna tilt management
may be necessary to identify areas of maximum intensity.
Along squall lines (multiple cells or clusters of cells in a line), individual cells
may be in different stages of development. Areas between closely spaced, intense
targets may contain developing clouds not having enough moisture to produce a
