Nexrad Limitations - Garmin GTN 625 Pilot's Manual

11.1.5.2

NEXRAD Limitations

NEXRAD radar images may have certain limitations:
• NEXRAD base reflectivity does not provide sufficient information to
determine cloud layers or precipitation characteristics. For example, it is
not possible to distinguish between wet snow, wet hail, and rain.
• NEXRAD base reflectivity is sampled at the minimum antenna elevation
angle. An individual NEXRAD site cannot depict high altitude storms at
close ranges. It has no information about storms directly over the site.
• Each square block on the display represents an area of four square
kilometers (2.15 NM). The intensity level reflected by each square
represents the highest level of NEXRAD data sampled within the area.
Block Area Is 4 km
(2.15 NM )
2
Block Area Is 4 km
(2.15 NM )
2
The following may cause abnormalities in displayed NEXRAD radar images:
• Ground clutter
• Strobes and spurious radar data
• Sun strobes (when the radar antenna points directly at the sun)
• Interference from buildings or mountains, which may cause shadows
• Metallic dust from military aircraft, which can cause alterations in radar
scans
190-01004-03 Rev. F
2
2
Figure 11-10 NEXRAD Data Blocks
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