A professional-grade decision-making engine for astrophotographers and astronomers, integrated directly into Windy.com.

This plugin analyzes complex atmospheric data to predict Seeing (turbulence) and Transparency (clarity), helping you decide if and what to shoot tonight.

• Seeing Prediction: Uses Jet Stream velocity (>200hPa) and surface wind to estimate atmospheric stability (arcseconds approximation).
• Transparency Score: Analyzes cloud layers (High/Mid/Low), humidity, and Precipitable Water Vapor (PWV).
• Air Quality Integration (CAMS): Real-time fetches of PM2.5 and Dust Mass to detect smoke, haze, or calima that might ruin deep-sky imaging.

• Scoring System: A weighted 0-100% score customized for:
  • DSO Mode: Prioritizes transparency and darkness (Moon phase).
  • Planetary Mode: Prioritizes atmospheric stability (Seeing) above all else.
• Equipment Recommendations: Suggests optimal focal lengths and warns if a Dew Heater is required.

• Cloud Structure: Breakdown of high, medium, and low clouds.
• Deep Sky Darkness: "Astro Twilight" usage and Moon illumination impact.
• Interactive UI: Hourly forecast table for the next 48h to find the perfect weather window.

1. Install:

   npm install

2. Run:

   npm start

3. Open Windy: Go to https://www.windy.com/developer-mode and load from https://localhost:9999/plugin.js.

The plugin retrieves Point Forecast data (European ECMWF & CAMS models) for the clicked location:

1. Jet Stream Analysis (250hPa): High winds in the upper tropopause are the #1 killer of good seeing.
2. Moisture Check: High humidity (>85%) or high PWV (>20mm) scatters light, reducing contrast.
3. Pollution Check: PM2.5 > 5µg/m³ or Dust Mass > 10µg/m³ triggers a transparency penalty.
4. Calculated Score: A subtractive algorithm starts at 100% and applies penalties based on the above factors.

• Svelte 3 (UI)
• Windy.com API (Maps & Data)
• TypeScript

Edgar Lopez
Clear Skies!