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Best Effort

The data are being made available on a best effort basis by all parties involved. There are no guarantees the data will be available when you really need it.

National Water Model Retrospective Version 1.2

  • 25 Year retrospective simulation (Jan 1 1993 - Dec 31 2017)
  • A reanalysis rather than a reforecast (forcing different than real-time runs)
  • Output fields are fewer and less frequent than real-time to conserve space
  • Provides historical context to current conditions
  • Can be used to infer flow frequencies and perform temporal analyses
  • 584,384 objects, 21.7 Tb in size, with hourly streamflow output and 3-hourly land surface output

Reanalysis Technical Details

  • Forced with NLDAS and NARR
  • 1992 used as a warmup period so the data in 1993 is good.
  • 1-km raster, 250-m raster, and vector data.
  • Uses the NHDPlus flow lines, lakes, and reservoirs.

File Formats

The data is being made available in a NetCDF file format. The data are a combination of raster in a projected format and vector data that must be referenced with associated geographical information located in other files.

Products Available & Name Conventions

There are several files which contain various output products for each time step. They are detailed below.

Product Name File Description Time Between Files Example File Name
CHRT Streamflow and other values at points associated with stream channel flow lines 1-hour 201409090000.CHRTOUT_DOMAIN1.comp
LAKE Output values at points associated with lakes & reservoirs 1-hour 201409090000.LAKEOUT_DOMAIN1.comp
LDAS Land surface model output including soil moisture, radiation, ET, snow, etc. at 1-km resolution 3-hourly 201409090000.LDASOUT_DOMAIN1.comp
RT Ponded water depth and depth to soil saturation at 250-m resolution 3-hourly 201409090000.RTOUT_DOMAIN1.comp

The filenames are


Archive Data Access

Data access is provided via a S3-API compatible service. The files may be downloaded with the aws cli, boto, or through a web browser.


This endpoint is S3-api compatible, so when you visit in your browser it will return XML with a truncated list of files available to download.

We recommend using the awscli or the python boto library to access the data. An example awscli command to list the contents of the bucket would look like:

aws s3 ls s3://nwm-archive/ --no-sign-request --endpoint-url https://griffin-objstore.opensciencedatacloud.org --no-verify-ssl

Real-time Data Access

If you could like to access a real-time data feed of forecasts from the National Water Model that data is available from NOAA at the following location.