Weather overlay: NEXRAD radar, satellite imagery, and NOAA aviation products

[billmallard]

Summary

Overlay real-time and near-real-time aviation weather products on the moving map. Weather awareness is among the highest-value additions to any EFB/moving map and is a primary factor in go/no-go decisions.

Data Sources

NEXRAD Radar

• Source: NOAA/NWS Multi-Radar Multi-Sensor (MRMS) mosaic tiles via AWS S3 (public, no auth required)
  • s3://noaa-mrms-pds/CONUS/MergedReflectivityQCComposite_00.50/
  • Updated every 2 minutes
• Alternative: Iowa State University NEXRAD tile server (Web Mercator tiles, easy to consume)
• Format: GeoTIFF or pre-tiled PNG with EPSG:4326 bounds

Satellite Imagery

• Source: NOAA GOES-East/West via AWS S3 (public)
  • Visible, IR, and water vapour channels
  • Updated every 5–10 minutes
• Alternative: RainViewer API (free tier available, radar + satellite)

Other Aviation Products

Product	Source	Update Cycle
METARs (station dots)	aviationweather.gov JSON API	Continuous
TAFs	aviationweather.gov	Hourly
PIREPs	aviationweather.gov	Continuous
SIGMETs / AIRMETs	aviationweather.gov	As issued
Winds aloft	aviationweather.gov	6-hourly
Icing (CIP)	aviationweather.gov	Hourly

Implementation Approach

1. Background thread fetches weather tiles/data on a configurable interval
2. Weather layer composited over the chart in paintEvent using QPainter opacity
3. METAR stations rendered as colour-coded dots (VFR green / MVFR blue / IFR red / LIFR magenta) matching standard EFB convention
4. Radar intensity mapped to standard NWS colour scale (green → yellow → red → purple)
5. Opacity control per layer so chart remains readable

Connectivity Consideration

Requires internet or ADS-B weather (FIS-B, 978 MHz UAT). Should degrade gracefully when offline — show last-known data with age indicator or go blank.

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