Six-hourly archives lack the hours apps need: WeatherBridge fills them with bidirectional transport, cutting held-out-hour error 48.6% below linear interpolation
Many global forecast archives store fields every six hours, while applications need hourly states. WeatherBridge reconstructs the interior state as query-conditioned bidirectional second-order transport between the two anchors, plus multiscale and spherical-harmonic residual corrections, and reaches the lowest aggregate error at held-out query hours on the 2020 ERA5 benchmark: normalised RMSE 0.07431 at six hours, 48.6% below linear interpolation's 0.144 and 9.0% below WeatherDCAE-14M. The advantage is not field-uniform; WeatherDCAE-14M remains better for geopotential and MSLP.