nwp-compose

For scientists who run forecasts, not Cylc

nwp-compose lets atmospheric scientists configure, launch, and monitor cycling NWP forecast workflows (MPAS and WRF) without hand-authoring Cylc. It is modular by component (ingest → prep → model → post → archive), supports both YAML-templated and bring-your-own-namelist configuration, and turns one workflow.yaml into a runnable Cylc 8 bundle you can cylc play.

Start from a template

nwp-compose new --template bahamas-mpas-rap scaffolds a known-good starter you tweak, instead of configuring from scratch.

Validated before it runs

Schema + graph + physics checks (CFL, decomposition legality) catch the mistakes that otherwise crash six hours into a run.

One command to the finish line

nwp-compose run chains validate → generate → install → play and hands you the concrete Cylc workflow id — the last mile, closed.

Yours, unprivileged

No sudo, no system services, no Docker daemon. State paths are $XDG-aware and redirectable to scratch. nwp-compose doctor checks your node before you run.

Find your path

Tutorial: your first forecast A guided walk from an empty directory to a cycling forecast — teaches the concepts as you go.

Migrating from bash + cron Consolidate a personal driver script + crontab into one validated, reproducible workflow.

The last mile: run & doctor Two commands that turn 'it validated' into 'it's running' — and tell you why when it isn't.

Interactive namelist configuration Edit templated parameters or preview a bring-your-own-namelist patch, with units and validation.

CLI reference Every command and flag.

Warning catalog (W1–W10) What each validator warning means and the concrete fix.

What this is — and is not

nwp-compose is the tool. The companion repo cylc-atm-workflow is the reference workflow (“Bahamas 3 km MPAS, built using nwp-compose”) and the golden-path integration test. The tool does not replace Cylc, do nested or DA cycling, run ensembles, or assume a cloud — see What is nwp-compose? for the honest scope line.