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🌌 Aurora Forecast Plugin

Version: 2.0.0
Last Updated: 2026-02-03
Category: Space Weather
Data Source: NOAA SWPC OVATION Aurora Model

Overview

The Aurora Forecast plugin visualizes real-time aurora probability forecasts from NOAA's OVATION (Oval Variation, Assessment, Tracking, Intensity, and Online Nowcasting) model. It displays the 30-minute aurora forecast as a color-coded overlay on the map, helping operators identify potential HF propagation disturbances and VHF/UHF aurora openings.

🌟 Features

Core Capabilities

30-Minute Aurora Forecast: NOAA OVATION model prediction
Global Coverage: Full Northern and Southern hemisphere visualization
Color-Coded Probability: Green → Yellow → Orange → Red (4-100%)
High Resolution: 1° latitude/longitude grid (360×181 points)
Real-time Updates: Refreshes every 10 minutes
Smooth Rendering: Anti-aliased interpolation for visual quality

Aurora Visualization

Color Ramp (matches NOAA official):
- Dark Green (4-25%): Low probability
- Green (25-40%): Moderate probability
- Yellow-Green (40-55%): Good probability
- Yellow-Orange (55-75%): High probability
- Orange-Red (75-90%): Very high probability
- Red (90-100%): Extreme probability
Transparency: Values <4% are transparent (noise filtering)
Opacity Control: Adjustable 0-100% (default 60%)

📊 Data Details

Data Source

Model: NOAA OVATION Aurora Forecast
Provider: NOAA Space Weather Prediction Center (SWPC)
API Endpoint: https://services.swpc.noaa.gov/json/ovation_aurora_latest.json
Update Frequency: Every 10 minutes
Forecast Horizon: 30 minutes ahead
Resolution: 1° latitude × 1° longitude
Data Points: ~65,000 grid cells (360×181)

Data Format

{
  "Forecast Time": "2026-02-03 16:45:00",
  "coordinates": [
    [longitude, latitude, probability],
    [0, 65, 42],    // 42% chance at 65°N, 0°E
    [90, 70, 78],   // 78% chance at 70°N, 90°E
    ...
  ]
}

Model Details

Physics-Based: Uses real-time solar wind data
Input Data: ACE/DSCOVR satellite observations
Propagation Time: ~1 hour from L1 point to Earth
Auroral Oval: Dynamically calculated based on geomagnetic activity
Kp Index Correlation: Higher Kp = larger/brighter aurora

🎯 Use Cases

1. HF Propagation Monitoring

Aurora can disrupt HF radio propagation, especially on polar paths.

High aurora probability = increased absorption on high-latitude paths
Monitor 20m-160m bands for impact
Avoid gray-line paths through active aurora zones

2. VHF/UHF Aurora Scatter

Strong aurora enables long-distance VHF/UHF contacts via aurora scatter.

50 MHz (6m): 500-1500 km contacts possible
144 MHz (2m): 500-1200 km contacts possible
432 MHz (70cm): 300-800 km contacts possible
Look for red/orange zones in your region

3. Contest/DXpedition Planning

Plan operating strategy around aurora conditions.

High aurora: Focus on mid-latitude paths
Low aurora: High-latitude paths open
Aurora openings: VHF/UHF operators activate

4. Space Weather Awareness

General situational awareness of geomagnetic conditions.

Correlates with Kp index
Indicates solar storm effects
Helps predict propagation changes

5. Visual Aurora Prediction

Plan aurora photography/viewing (requires clear skies).

Red zones (>75%): Excellent chance of visible aurora
Yellow zones (40-75%): Good chance with dark skies
Green zones (4-40%): Possible with very dark skies

🔧 Usage

Basic Setup

Enable Plugin
- Open Settings → Map Layers
- Toggle 🌌 Aurora Forecast
- Forecast overlay appears immediately
Adjust Opacity
- Use the Opacity slider (0-100%)
- Default: 60%
- Higher opacity = more visible aurora zones
- Lower opacity = see underlying map better
Interpret Colors
- Green: Low to moderate probability
- Yellow: Good probability
- Orange: High probability
- Red: Very high/extreme probability

Reading the Forecast

For HF Operators

Green aurora near your path: Minimal impact
Yellow/orange aurora on path: Possible degradation
Red aurora on path: Significant absorption likely
Aurora equatorward of your location: Possible propagation enhancement on east-west paths

For VHF/UHF Operators

Your location in red zone: Excellent aurora scatter potential
Your location in orange zone: Good aurora scatter potential
Your location in yellow zone: Possible weak aurora scatter
Beam toward aurora: Point antenna toward auroral oval (usually north in Northern Hemisphere)

Timing

Forecast: 30 minutes ahead (use current conditions for immediate assessment)
Update frequency: Every 10 minutes (real-time tracking)
Best accuracy: Within 1-2 hours of major geomagnetic events

⚙️ Configuration

Default Settings

{
  enabled: false,
  opacity: 0.6,  // 60%
  updateInterval: 600000,  // 10 minutes
  minProbability: 4,  // Filter <4%
  resolution: '1°',
  colorScheme: 'NOAA Official'
}

Color Mapping Algorithm

// Probability 4-100 mapped to color ramp
function auroraCmap(probability) {
  if (probability < 4) return null;  // Transparent
  
  const t = (probability - 4) / 80;  // Normalize to 0-1
  
  // Green → Yellow → Orange → Red gradient
  // Alpha increases with probability (0.3 → 1.0)
}

🧪 Technical Details

Implementation

Technology: Leaflet ImageOverlay
Canvas Rendering: HTML5 Canvas API
Resolution: 360×181 grid upscaled to 720×362 with anti-aliasing
Projection: Equirectangular (matches NOAA grid)
Longitude Shift: Corrected for -180° to +180° map coordinates

Performance

Data Size: ~200 KB JSON per fetch
Render Time: <200ms for canvas generation
Canvas Size: 720×362 pixels (smoothed 2× upscale)
Memory: ~2 MB for overlay layer
Network: Fetches every 10 minutes

Data Flow

NOAA OVATION Model → SWPC JSON API → OpenHamClock Proxy → Canvas Rendering → Map Overlay
   (real-time)         (10 min cache)    (fetch on demand)    (<200ms)       (instant)

Coordinate Transformation

// NOAA grid: lon 0-359°, lat -90° to +90°
// Leaflet: lon -180° to +180°, lat -90° to +90°

// Shift longitudes for map alignment
x = (lon >= 180) ? lon - 180 : lon + 180;

// Flip latitudes for canvas (top = north)
y = 90 - lat;

🔍 Troubleshooting

No Aurora Overlay Showing

Check internet connection: Requires live NOAA data
Opacity: Increase opacity slider
Low activity: During solar minimum, aurora may be weak/absent
Browser cache: Clear cache and reload (Ctrl+F5)

Overlay Looks Pixelated

This is normal: 1° resolution grid (111 km at equator)
Upscaling applied: 2× smoothing with anti-aliasing
Physics limitation: Model resolution is 1°

Data Not Updating

Auto-refresh: Plugin refreshes every 10 minutes automatically
Manual refresh: Toggle plugin off/on to force refresh
NOAA SWPC: Check https://www.swpc.noaa.gov for service status

Color Too Dim/Bright

Adjust opacity: Use slider (try 50-80%)
Low probability: Green colors are subtle by design
High probability: Red colors are vivid (rare during low activity)

🌐 External Links

NOAA SWPC: https://www.swpc.noaa.gov
OVATION Model: https://www.swpc.noaa.gov/products/aurora-30-minute-forecast
Aurora Tutorial: https://www.swpc.noaa.gov/content/tips-viewing-aurora
Current Conditions: https://www.swpc.noaa.gov/communities/radio-communications
Kp Index: https://www.swpc.noaa.gov/products/planetary-k-index

📝 Version History

v2.0.0 (2026-02-03)

High-resolution 1° grid (360×181 points)
NOAA official color ramp (green → red)
Smooth rendering with 2× anti-aliasing
Proper longitude shift for map alignment
Optimized canvas generation (<200ms)
10-minute auto-refresh
Probability filtering (<4% transparent)

v1.0.0 (Initial Release)

Basic OVATION aurora forecast
Simple overlay rendering
Manual refresh only

💡 Tips & Best Practices

For HF Operators

Compare with WSPR: Check if high-latitude WSPR paths are weak/absent
Gray line awareness: Combine with Gray Line plugin to see aurora impact on terminator paths
Band selection: Lower bands (80m, 160m) more affected than higher bands (15m, 10m)
Alternate paths: Route around aurora (use mid-latitude paths)

For VHF/UHF Operators

Red zones = activate: Strong aurora = excellent scatter potential
CW mode: Aurora scatter sounds "raspy" or "hissy"
SSB challenges: Aurora Doppler spreading makes SSB difficult
Digital modes: FT8/MSK144 work better than SSB
Beam north: Point antenna toward auroral oval

Common Workflows

Daily Check: Enable at start of operating session
Storm Watch: Monitor during solar storm events (CME arrivals)
Contest: Leave enabled to track propagation changes
Aurora Chase: VHF/UHF operators watch for red zones in their region

Combining with Other Plugins

WSPR + Aurora: Identify absorption on high-latitude paths
Gray Line + Aurora: See aurora interference on terminator paths
Earthquakes + Aurora: Both can affect ionosphere (different mechanisms)

🏷️ Plugin Metadata

{
  id: 'aurora',
  name: 'Aurora Forecast',
  description: 'NOAA OVATION aurora probability forecast (30-min)',
  icon: '🌌',
  category: 'space-weather',
  defaultEnabled: false,
  defaultOpacity: 0.6,
  version: '2.0.0'
}

📄 License & Attribution

Data Source: NOAA Space Weather Prediction Center (SWPC)
Model: OVATION (Oval Variation, Assessment, Tracking, Intensity, and Online Nowcasting)
Data License: Public Domain (U.S. Government)

73 de OpenHamClock 📡🌌

Auroral awareness for the prepared operator

10 KiB Raw Blame History Unescape Escape

🌌 Aurora Forecast Plugin

Overview

🌟 Features

Core Capabilities

Aurora Visualization

📊 Data Details

Data Source

Data Format

Model Details

🎯 Use Cases

1. HF Propagation Monitoring

2. VHF/UHF Aurora Scatter

3. Contest/DXpedition Planning

4. Space Weather Awareness

5. Visual Aurora Prediction

🔧 Usage

Basic Setup

Reading the Forecast

For HF Operators

For VHF/UHF Operators

Timing

⚙️ Configuration

Default Settings

Color Mapping Algorithm

🧪 Technical Details

Implementation

Performance

Data Flow

Coordinate Transformation

🔍 Troubleshooting

No Aurora Overlay Showing

Overlay Looks Pixelated

Data Not Updating

Color Too Dim/Bright

🌐 External Links

📝 Version History

v2.0.0 (2026-02-03)

v1.0.0 (Initial Release)

💡 Tips & Best Practices

For HF Operators

For VHF/UHF Operators

Common Workflows

Combining with Other Plugins

🏷️ Plugin Metadata

📄 License & Attribution

10 KiB

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