Garmin GXM 30A - Manual (Page 15)

GXM 30A XM Radio Smart Antenna Owner’s Manual 
Lightning
Lightning strikes are represented by lightning bolt icons, as shown in the images below. Lightning appears on the map if strikes
were detected within the last seven minutes. The ground-based lightning detection network only detects cloud-to-ground lightning.
XM W
eather
f
eatures
> l
IghtnIng
Lightning bolts indicate a
cloud-to-ground lightning
strike.