Lesson 2 - Decoding the Forecast

Key Takeaways:

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• Synoptic Weather Charts:

  • Show highs (H), lows (L), isobars, and fronts.

  • Tightly packed isobars = strong winds.

  • Wind flows clockwise around highs and counter-clockwise around lows in the Northern Hemisphere.

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• GRIB Files:

  • Show forecast data (wind, pressure, rain, etc.) in visual format.

  • Need interpretation—no symbols or explanations.

  • Available via apps like Windy and PredictWind.

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• Best Forecast Tools:

  • Windy: Visual overlays, multiple models.

  • PredictWind: GRIBs, routing, passage planning.

  • Navionics + Weather: Combines navigation and forecast in one.

  • NAVTEX/VHF: Text-based but reliable when offline.

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• Forecast Models to Know:

  • GFS: Global, free, good for general trends.

  • ECMWF: Higher accuracy, especially in Europe.

  • ICON/AROME: High-resolution, good for local detail.

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• Strategy:

  • Always compare multiple sources.

  • Update forecasts regularly, especially before departure and en route.

  • Trust your observations alongside data.