How barometer.today builds its animated global isobar maps using open weather data

Barometer.today, part of the SimpleMeteo.com network, generates animated world isobar maps updated four times daily using ECMWF global forecast data fetched via a self-hosted Open-Meteo server. The maps display sea-level pressure contours hour by hour, spanning from 24 hours in the past to four days ahead, with roughly 120 frames produced per model update cycle. Raw grid data is smoothed using a Gaussian blur to eliminate jagged contour lines, though the blur radius is carefully limited to avoid masking extreme weather events such as hurricanes. A key technical challenge involves high-altitude plateaus like the Himalayas and Andes, where sea-level pressure calculations are mathematically extrapolated over non-existent air, potentially skewing nearby values by several hectopascals. The team addresses this with a normalized convolution technique that excludes elevated terrain cells from the blur, while rendering isobars over those masked regions as dashed lines to signal extrapolated data.