Garmin GNC 420W Pilots Guide - Page 209

Weather Products, NEXRAD Description, NEXRAD Abnormalities, NEXRAD Limitations, States, Alaska

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SECTION 11 ADDITIONAL FEATURES Weather Products The following weather products are available for display on the GNC 420 unit via the Weather Data Link interface: • NEXRAD Data • Graphical METAR Data • Text-based METAR Data • Graphical Temperature/Dewpoint Data • Graphical Wind Data NEXRAD Description WSR-88D weather surveillance radar or NEXRAD (NEXt generation RADar) is a Doppler radar system that has greatly improved the detection of meteorological events such as thunderstorms, tornadoes, and hurricanes. An extensive network of NEXRAD stations provides almost complete radar coverage of the continental United States, Alaska, and Hawaii. The range of each NEXRAD station is 124 nautical miles. NEXRAD Abnormalities There are possible abnormalities regarding displayed NEXRAD images. Some, but not all, of those include: • Ground clutter • Spurious radar data • Sun strobes, when the radar antenna points directly at the sun • Military aircraft deploy metallic dust (chaff) which can cause alterations in radar scans • Interference from buildings or mountains, which may cause shadows NEXRAD Limitations CAUTION: NEXRAD weather data is to be used for long-range planning purposes only. Due to inherent delays and relative age of the data that can be experienced, NEXRAD weather data cannot be used for short-range avoidance of weather. Certain limitations exist regarding the NEXRAD radar displays. Some, but not all, are listed for the user's awareness: • NEXRAD base reflectivity does not provide sufficient information to determine cloud layers or precipitation characteristics (hail vs. rain, etc.). • NEXRAD base reflectivity is sampled at the minimum antenna elevation angle. An individual NEXRAD site cannot depict high altitude storms at close ranges, and has no information about storms directly over the site. • NEXRAD resolution varies, depending on the amount and complexity of the weather data being received. The displayed NEXRAD data will reflect the highest intensity level sampled within a 4 sq km area (depending on available system memory). 190-00140-20 Rev. K GNC 420(A) Pilot's Guide and Reference 11-19

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GNC 420(A) Pilot’s Guide and Reference
11-19
SECTION 11
ADDITIONAL FEATURES
190-00140-20
Rev. K
Weather Products
The following weather products are available for
display on the GNC 420 unit via the Weather Data Link
interface:
•
NEXRAD Data
•
Graphical METAR Data
•
Text-based METAR Data
•
Graphical Temperature/Dewpoint Data
•
Graphical Wind Data
NEXRAD Description
WSR-88D weather surveillance radar or NEXRAD
(NEXt generation RADar) is a Doppler radar system that
has greatly improved the detection of meteorological
events such as thunderstorms, tornadoes, and hurricanes.
An extensive network of NEXRAD stations provides
almost complete radar coverage of the continental United
States, Alaska, and Hawaii.
The range of each NEXRAD
station is 124 nautical miles.
NEXRAD Abnormalities
There are possible abnormalities regarding displayed
NEXRAD images.
Some, but not all, of those include:
•
Ground clutter
•
Spurious radar data
•
Sun strobes, when the radar antenna points
directly at the sun
•
Military aircraft deploy metallic dust (chaff) which
can cause alterations in radar scans
•
Interference from buildings or mountains, which
may cause shadows
NEXRAD Limitations
CAUTION:
NEXRAD weather data is to be used
for long-range planning purposes only.
Due to
inherent delays and relative age of the data
that can be experienced, NEXRAD weather data
cannot be used for short-range avoidance of
weather.
Certain limitations exist regarding the NEXRAD
radar displays.
Some, but not all, are listed for the user’s
awareness:
•
NEXRAD base reflectivity does not provide
sufficient information to determine cloud layers or
precipitation characteristics (hail vs. rain, etc.).
•
NEXRAD base reflectivity is sampled at the
minimum antenna elevation angle.
An individual
NEXRAD site cannot depict high altitude storms
at close ranges, and has no information about
storms directly over the site.
•
NEXRAD resolution varies, depending on the
amount and complexity of the weather data being
received.
The displayed NEXRAD data will reflect
the highest intensity level sampled within a 4 sq
km area (depending on available system memory).