It takes location readings only once a week and maps them onto a grid point rather than anything more specific.

Data that form grid point that identifies grid cell are needed.

Finite differences are usually the cheapest on a per grid point basis followed by the finite element method and spectral method.

From there, grid point values for each variable are interpolated into each grid cell, which can then be analyzed.

Prognostic equations for each relevant physical process are run for each grid point.