Missing Radar Coverage on My Garmin Display

Introduction:

This support article will help address the common question of why you may be experiencing a lack of radar coverage on your map.  Garmin understands the importance of having access to reliable weather information, and Garmin is here to help you troubleshoot and understand the possible reasons behind this issue.  

Here Are Some Possible Reasons for Missing Radar Coverage:

• There are simply no radar stations in the area.  Radar coverage is limited by the line-of-sight principle. If you are located far away from the radar site, you might experience a gap in coverage. Radar signals can be obstructed by buildings, mountains, or terrain, decreasing their reach.

• Radar Beam Elevation.  Radar beams are not perfectly flat; they gradually rise with distance.  If you are situated at a lower elevation, the radar beam may pass over your location, resulting in limited or no coverage.

• There could be a radar outage or maintenance.  Radar systems occasionally undergo maintenance or experience technical issues that can lead to temporary outages or reduced coverage.

• Regional and Continental versions of NEXRAD have different coverage areas.  The regional NEXRAD weather product coverage area varies, as it is determined by the data being received from ground-based sources.  The continental US version of the NEXRAD weather product is not available above 60 degrees latitude.

  • At smaller map ranges, individual blocks of NEXRAD weather data are viewable. For the regional version of the NEXRAD weather product, the smallest block represents 1.5 nm wide by 1 nm tall.

  • The continental United States version of the NEXRAD weather product is generally lower in resolution than the regional NEXRAD data. The color of each block represents the highest radar reflectivity detected within that area.

• NEXRAD/PRECIP and Terrain overlay functions are mutually exclusive on Garmin displays.  Enabling one automatically disables the other.

How can I Determine if I am Within Radar Coverage?

To check if you are within radar coverage, you can refer to this map provided by NOAA:

NEXRAD Coverage Below 10,000 Feet AGL

See Full coverage map for additional areas.

In Addition to Missing Radar Coverage, 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 can cause alterations in radar scans.

How Do I Know if There’s Missing Radar, and What Do These Missing Areas Look Like?

• FAA regulations require Garmin to show those areas with no coverage on the map; this is why you may see these missing areas in our certified avionics and not in other products or elsewhere online.

• A semi-transparent or fully opaque mask indicates regions where data may be missing or incomplete. Color is dependent upon the presence of topographical data. The mask is purple when there is no underlying topographical data, such as on the FIS-B weather display, or on the Map when the TOPO overlay is off.

• Here are a few examples of missing radar data taken from the G500 TXi™ electronic touchscreen display Pilot's Guide:

There are many possible reasons for the lack of radar coverage on your map.  A clear understanding of ground-based Doppler weather radar capabilities will allow you to interpret the NEXRAD weather imagery in the safest way possible. For additional information, please see the National Oceanic and Atmospheric Administration’s page on Doppler radar technology.