How to read AEMET forecasts

1. Why AEMET data is reliable

National agencies like AEMET are among the most rigorous official sources in the global meteorological landscape, sustaining a vast infrastructure of radars, satellites, and thousands of automated real-time stations.

• First-hand data: Unlike many apps that resell third-party data, AEMET generates its own measurements and applies Spain-specific local corrections.
• HARMONIE-AROME: AEMET's own high-resolution model, running at a 2.5 km grid. It captures terrain influence on wind well, making it especially useful in complex coastal areas.
• Human Supervision: In chaotic atmospheric scenarios, a corps of meteorologists adjusts the supercomputers' parametric guidelines to fine-tune the output.

WindTrackr pulls AEMET data directly and layers it with live readings from our coastal sensor network.

2. What the forecast icons mean

Forecast symbols follow World Meteorological Organization standards. Here is what you need to know to read them correctly:

• Dominant Sun: Elevated pressures and stability. Suggests safe conditions but warns of the absence of vigorous mechanical fronts. Total reliance on thermal heating.
• Stagnant Cloud Cover: The lack of direct solar radiation severely inhibits the development of thermal gradients and local sea breezes.
• Precipitation: Solid symbols indicate a precipitation probability above 70%. Dashed symbols mark intermittent intervals. Always check the accumulated rainfall in millimetres, not just the percentage.
• Lightning: Red alert. Salt water and carbon/aluminium materials create deadly conditions during electrical storms. Exit the water immediately.

3. What the rain percentage actually means

The "70% rain" metric harbors one of the greatest misunderstandings in atmospheric sciences. It does not imply rain over 70% of the time.

• What 70% actually means: The model has analysed similar weather situations in the past. In 70% of those cases it rained. It does not mean rain for 70% of the day.
• Cell Coverage: The model assigns probability to an extensive geographic cell. Your precise beach enclave could be located on the dry border of that spatial grid.
• Micro-millimetry: Agencies classify a "wet day" at the slightest trace (0.1 mm). An ephemeral isolated shower validates 100% of the day's statistical metric.
• Volume Evaluation: Ignore the empty percentage; focus on the precipitation sum (mm). 80% with 0.3 mm indicates simple drizzle; 40% with 20 mm announces powerful convective downpour cells.

Through joint observation of barometric pressures and relative humidity levels on our platform, you can detect false positives and dodge storm bands in advance.

4. Sensor Readings vs. Wind Forecasting

Models calculate wind at 10 metres above ground level — that is what you see in forecasts. A few things matter when interpreting those numbers:

• Mean wind vs gust gap: A forecast showing 10 knots average with 25 knots gust has a 15-knot gap — a clear sign of irregular, turbulent conditions.
• Uncertainty ranges: Models widen their probability ranges in simulations beyond 48h. When in doubt, assume the maximum peaks as a reference for your gear's safety management.
• Micro-topographic Limitations: Coastal mountain ranges or architectural barriers massively alter generated wind profiles. Model precision at macro scale dilutes at the shore. Herein lies the incalculable value of the hyper-local sensor matrix.

5. Weather models: ECMWF, GFS, and HARMONIE

Several global models are used by AEMET and other agencies to generate forecasts. Each has its strengths:

• ECMWF: The European model, the global reference. Runs at a 9 km grid and is very reliable for 7 to 10-day outlooks.
• HARMONIE-AROME: AEMET's high-resolution model (2.5 km grid). Far more precise than ECMWF at local scale, especially within the first 48 hours.
• The GFS Alternative: North American numerical system; historically a step behind European computation in regional fidelity, useful for long-term second opinions.
• Ensemble models: The center runs 50 simulations with slightly different starting data. High convergence indicates high reliability; extreme divergence warns of unpredictable scenarios.

6. Combining forecasts with sensor data

The most effective approach is to combine AEMET forecasts with WindTrackr's live sensor data:

• Two days out: Check long-range models for incoming fronts or significant weather changes. This is when you plan.
• Six hours out: Check whether nearby station readings are picking up as the model predicted. If the timing tracks, the forecast is on.
• Tactical Phase (H -0.5): Discard the mathematical simulation. Employ the raw data dump (Live) flowing onto your screen from the beach. Configure your harness and sails according to the sensor's true pulse.

Mathematical triangulation puts you on the right path; but the digital anemometer is what turns on the green light to hit the water with full confidence.

Takeaway

AEMET is a very powerful tool, but it is not infallible. No model can predict exactly what will happen at your specific beach, especially in coastal areas with complex local weather patterns. Use it to judge whether a day has potential, then check WindTrackr's sensors in the hours before to confirm conditions are actually coming together.