Weather Mapping And Interpretation; Weather Display Interpretation - Garmin GTN 750 Pilot's Manual Upgrade Supplement

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
Approximate
Color
Intensity
BLACK < 23 dBZ
GREEN 23 dBZ to < 33 dBZ
YELLOW 33 dBZ to < 41 dBZ
RED 41 dBZ to < 50 dBZ
MAGENTA
50 dBZ and greater
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
190-01007-03 Rev. Q
GWX 68 Radars
Approximate
Rainfall Rate
(in/hr)
< .01
.01 - 0.1
0.1 - 0.5
0.5 - 2
> 2
Table 12-29 Precipitation Intensity Levels
GTN 725/750 Pilot's Guide
GWX 70 Radars
Radar Return
Approximate
Intensity
< 23 dBZ
23 dBZ to < 33 dBZ
33 dBZ to < 41 dBZ
41 dBZ to < 49 dBZ
> 49 dBZ
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Appendix
12-41
Index