Revision 6 Feb/2009
KMD 550/850 FIS Addendum
15
The resolution of NEXRAD XM data is 2 km. Thus, when zoomed in on
the display, each square block is 2 km on a side. The intensity level
reflected by the square will be the highest level sampled within the 2 km
area.
INTENSITY
Precipitation intensity is depicted using colors as follows:
Green Light Level 1 15-30 dBz (10-30 dBz for XM))
Yellow Moderate Level 2 30-40 dBz
Red Heavy Level 3-4 40-50 dBz
Magenta Extreme Level 5-8 50+ dBz
The NEXRAD dBz levels, descriptions and colors are consistent with
FAA guidelines.
Moving the joystick and
pressing the MORE INFO
softkey will display the
NEXRAD legend as shown
in Figure 3a (FIS VDL) and
3b (XM WX).
The column labeled dBz is a
measure of the radar echo
intensity.
The strength of a radar
return signal typically varies
as a function of distance
(i.e., weaker from distant tar-
gets, stronger from those
nearby) and the object size.
Many weather sources avail-
able on the internet use
color coding that is different
than the KMD 550/850 color
coding. The dBz and inten-
sity level can be used to
compare intensity levels
between different sources of
NEXRAD information since
many internet weather
providers will include a
legend with dBz values indi-
cated.
No Data, as shown in the legend, indicates the lack of coverage for
reasons discussed previously.
Figure 3a
Value Added Service Weather Products
Figure 3b
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