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NOAA National Water Model — products & configurations#

The curated catalog (nwm_data_catalog.yaml) has two blocks: products (what a file contains) and configurations (which operational run produced it). A concrete S3 key is assembled from a (configuration, product, cycle, step) tuple. The catalog covers all six products and all 55 operational configurations on the bucket; Catalog().available_datasets and Catalog().available_configurations are the full indices.

Products#

Key NWM file OUTPUT_KIND Indexed by Retrospective Zarr
chrtout channel_rt tabular feature_id (NHDPlus reach) chrtout.zarr
lakeout reservoir tabular feature_id (reservoir) lakeout.zarr
coastal total_water tabular SCHISM mesh node —
ldasout land raster 1 km grid (y, x) ldasout.zarr
rtout terrain_rt raster 250 m routing grid —
forcing forcing raster model grid precip.zarr

Variable sets (units in parentheses), as read from the live files:

  • chrtout — streamflow (m3 s-1), velocity (m s-1), nudge (m3 s-1), qSfcLatRunoff (m3 s-1), qBucket (m3 s-1), qBtmVertRunoff (m3).
  • ldasout — SOIL_M (m3 m-3), SNEQV (kg m-2), SNOWH (m), FSNO (1), ACCET (mm), SOILSAT_TOP (1), SNOWT_AVG (K).
  • lakeout — inflow (m3 s-1), outflow (m3 s-1), water_sfc_elev (m), reservoir_type (1), reservoir_assimilated_value (m3 s-1).
  • rtout — zwattablrt (m), sfcheadsubrt (mm).
  • forcing — RAINRATE (mm s-1), T2D (K), Q2D (kg kg-1), U2D (m s-1), V2D (m s-1), PSFC (Pa), SWDOWN (W m-2), LWDOWN (W m-2).
  • coastal — elevation (m).

Configurations#

All 55 are curated. The major CONUS ones:

Configuration Cycles/day Steps Horizon Ensemble
short_range 24 (hourly) f001…f018 18 h —
analysis_assim 24 (hourly) tm00…tm02 look-back —
analysis_assim_extend 1 (16 UTC) tm00…tm27 28 h look-back —
analysis_assim_long 4 tm00…tm11 12 h look-back —
medium_range 4 (00/06/12/18) f003…f240 240 h members 1–6
medium_range_blend / medium_range_no_da 4 f003…f240 240 h —
long_range 4 f006…f720 (6 h) 720 h members 1–4
forcing_* per family — — —

…plus the regional domains — *_alaska, *_hawaii, *_puertorico (the Hawaii/Puerto Rico short-range runs are sub-hourly: 5-digit f00015, f00030, … at a 15-minute cadence) — and the coastal domains *_coastal_{atlgulf,hawaii,pacific,puertorico} (the coastal product). Each carries the right cycles_utc, step_kind, step_width, horizon, cadence, members, and product list. List them all:

from earthlens.nwm import Catalog
cat = Catalog()
cat.available_configurations        # all 55 configuration keys
cat.get_config("short_range_hawaii").step_width   # 5 (sub-hourly)

S3 key layout#

nwm.{YYYYMMDD}/{configuration-dir}/nwm.t{HH}z.{family}.{output}.{step}.{domain}.nc
  • The directory is the configuration key (short_range, analysis_assim_hawaii, short_range_coastal_atlgulf), with a _mem{N} suffix for an ensemble.
  • {family} is the configuration's file-name token, {output} the product's S3 token (channel_rt, land, …); for an ensemble the member rides on the output token (channel_rt_1).
  • {step} is f{NNN} for forecasts or tm{NN} for analyses, zero-padded to the configuration's step width (f001, tm00, f00015).

Example: nwm.20260526/short_range/nwm.t00z.short_range.channel_rt.f001.conus.nc

Tooling#

# List the live configurations and diff them against the bundled catalog.
earthlens datasets refresh nwm
# Flag any curated configuration no longer served live; exit non-zero on drift.
earthlens datasets audit nwm --strict

Both commands walk the most recent complete nwm.YYYYMMDD/ day on the unsigned noaa-nwm-pds bucket (ensemble-member directories are collapsed to their base configuration key). The assimilation-input usgs_timeslices directory is a live configuration the catalog deliberately does not curate, so it surfaces as an untracked id (informational), not drift.