Thunderstorms - Garmin GTN 725 Pilot's Manual

Foreword
Weather
Getting
Started
Mode
Audio &
Color
Xpdr Ctrl
Com/Nav
BLACK
FPL
GREEN
YELLOW
Direct-To
RED
MAGENTA
Proc
Charts
12.3.5.2
Updrafts and downdrafts in thunderstorms carry water through the cloud.
Wpt Info
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
Map
is displayed on the weather radar. Avoid these areas by an extra wide margin.
Traffic
• In areas where the displayed target intensity is red or magenta (indicating
large amounts of precipitation), the turbulence is considered severe.
Terrain
• Areas that show steep color gradients (intense color changes) over thin bands
or short distances suggest irregular rainfall rate and strong turbulence.
Weather
• Areas that show red or magenta are associated with hail or turbulence, as
Nearest
well as heavy precipitation. Vertical scanning and antenna tilt management
may be necessary to identify areas of maximum intensity.
Services/
Music
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
Utilities
targets may contain developing clouds not having enough moisture to produce a
return. However, these areas could have strong updrafts or downdrafts. Targets
System
showing wide areas of green are generally precipitation without severe turbulence.
Messages
Irregularities in the target return may also indicate turbulence, appearing as
"hooks," "fingers," or "scalloped" edges. These irregularities may be present in
Symbols
green areas with no yellow, red, or magenta areas and should be treated as highly
dangerous areas. Avoid these areas as if they were red or magenta areas.
Appendix
12-40
Index
GWX 68 Radars
Approximate
Approximate
Rainfall Rate
Intensity
< 23 dBZ
23 dBZ to < 33 dBZ
33 dBZ to < 41 dBZ
41 dBZ to < 50 dBZ
50 dBZ and greater
Table 12-5 Precipitation Intensity Levels

Thunderstorms

Garmin GTN 725/750 Pilot's Guide
GWX 70 Radars
Approximate
Intensity
(in/hr)
< .01 < 23 dBZ
.01 - 0.1 23 dBZ to < 33 dBZ
0.1 - 0.5 33 dBZ to < 41 dBZ
0.5 - 2 > 41 dBZ
> 2 Turbulence Detection
3rd Party
Radars
Radar Return
Level (see
radar docu-
mentation
for details)
0
1
2
3
4
190-01007-03 Rev. D