Northern Lights Anchorage Tonight

OVATION Prime Model

The Kp value shown above is calculated specifically for Anchorage's GPS coordinates (61.2181°N, 149.9003°W) using the OVATION Prime aurora forecast model from NOAA's Space Weather Prediction Center.

Data Source

JSON Endpoint: https://services.swpc.noaa.gov/json/ovation_aurora_latest.json

Update Frequency: Every 30 minutes

Data Format: Array of coordinates [longitude, latitude, aurora_intensity]

Calculation Process

1. Fetch Global OVATION Data: The system retrieves the complete global aurora forecast from NOAA's OVATION Prime model, which contains thousands of coordinate points covering the entire auroral oval.
2. Find Nearest Point: The algorithm searches through all OVATION coordinate points to find the one closest to Anchorage's exact GPS coordinates (61.2181°N, 149.9003°W). This uses distance calculation that accounts for longitude wrapping at the International Date Line.
3. Extract Aurora Intensity: Each OVATION coordinate point contains an intensity value (0-100) representing the probability or energy flux of aurora at that location. This value is extracted from the nearest point.
4. Convert to Kp: The OVATION intensity/probability is converted to Kp using an empirical relationship based on the OVATION-Prime model:
   • 0-20% probability → Kp 0-2 (quiet conditions)
   • 20-40% probability → Kp 2-4 (unsettled to active)
   • 40-60% probability → Kp 4-5 (minor geomagnetic storm)
   • 60-80% probability → Kp 5-6 (moderate storm)
   • 80-100% probability → Kp 6-9 (strong to extreme storm)

Why Location-Specific Kp?

The global Kp index represents average geomagnetic activity across the planet, but aurora visibility varies significantly by location. OVATION Prime provides location-specific predictions by modeling the auroral oval's shape and intensity at each coordinate point. This means Anchorage gets a Kp value calculated from the actual aurora forecast at its exact coordinates, not a global average.

Same Data as 3D Global Map

This calculation uses the exact same OVATION Prime data that powers the interactive 3D global aurora map with the ovation ring visualization. The difference is that this page calculates a specific Kp value for Anchorage's coordinates, while the map visualizes the entire global auroral oval.