Garmin G1000H Bell 407GX Pilot's Guide - Page 304

HAZARD AVOIDANCE NEXRAD Limitations NEXRAD radar images may have certain limitations: • NEXRAD base reflectivity does not provide sufficient information to determine cloud layers or precipitation characteristics (wet hail vs. rain). 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. • When zoomed in to a range of 30 nm, each square block on the display represents an area of four square kilometers. The intensity level reflected by each square represents the highest level of NEXRAD data sampled within the area (Figure 6-12). Block Area is 4 km2 Figure 6-12 NEXRAD Data - Zoomed 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 292 Garmin G1000H™ Pilot's Guide for the Bell 407GX 190-01255-00 Rev. A