Input Data for Initializing WRF-NMM

Input Data General Overview

Input data is available from a number of regional and global forecast models. At this time, the WRF-NMM SI has been tested on GRIB files from:

NAM (formerly Eta)

NCEP/EMC's 12 km regional model. The Eta/NAM forecasts are distributed at various resolutions. Two popular distribution grids for initializing WRF are grids 212 and 221. Grid 212 is a 40 km grid that covers southern Canada, the continental US, and northern Mexico. Grid 221 is a 32 km grid that covers nearly the entire NAM domain. Forecast hours from 0 to 84 are available 4 times daily at 3 hourly interval.


NCEP/EMC's Global Forecasting System. Forecast hours from 0 to 384 are availably 4 times daily at 6 hour interval.

NCEP/NCAR Reanalysis Project data

NCEP/EMC's 13 km Rapid Update Cycle regional model


NCEP/NCAR Reanalysis Project data

Potential sources of input data

Real-time data

NCEP's public ftp-site provides a variety of regional (NAM) and global (GFS) data in GRIB format that can be used to initialize WRF in real-time. Only the forecast cycles for the past 24 hours are available on the NCEP ftp site. To obtain data for past cases from NOAA/NCEP, one must submit a formal request. No public ftp site is available for past-date data.

Non-real-time data

A number of datasets that can be used as input to WRF-NMM SI can be downloaded directly from the NCAR/DSS web site. This data is available to all users to download (no charge).