GRIB data

Because of the complexity of GRIB data and the fact that it is not fully supported by Digital Atmosphere yet, Weather Graphics Technologies will not provide assistance in locating, retrieving, or using GRIB data.  It is provided as-is.  Comments are welcomed but we may not be able to respond to questions. If you need help, please access our public discussion group on our website at


The majority of GRIB output data is available from supercomputer models, such as the ETA model output provided by the National Center for Environmental Prediction near Washington DC. Sources of data include:


Documentation for the GRIB format includes: (MMM model codes) (grids with pole point listings) (lists grids w/ images and model codes in current use) (GRIB naming conventions) (Complete documentation) (more documentation)


New NWS GRIB filename convention

Since 2002, the NWS has used a hierarchichal naming convention that forms a URL. An example is:

This shows that at the central server location (SL.us008001), one can find operational status data (ST.opnl) consisting of the Eta 00Z cycle model (MT.eta_CY.00) produced on 09 Oct 2003 (RD.20031009). Within this one can find GRIB data (PT.grid_DF.gr1) consisting of data for the 00h forecast hour mapped onto the AWIPS 211 grid (fh.0000_tl.press_gr.awp211).

For more information on this naming convention see (Directory and File Naming Standards)
and (TGFTP File Reference).
Information on grids is at


Old NWS GRIB filename convention

The legacy filename format for NWS GRIB data is as follows. Some datasets can still be found in the top-level directory at which use this filename convention.

Sample: us008_gf000_02020300_HxXAx

Portions: us008_gfMMM_YYMMDDHH_ADGT

Here is what each field means:

MMM - Model code. Underlined codes are in current use as of February 2002; others are obsolete and are listed only for historical purposes. 000=Experimental, 010=GlobalWindWave, 039=NGM, 044=SeaSfcTemp, 076=MRFbiascorrected, 077=AVNfcst, 078=MRF, 080=MRF, 081=AVNinit, 082=MRFinit, 083=ETA80km, 084=ETA22km, 085=ETA29km, 086=RUC60km, 089=ETA48km, 094=MRF-T170/L42, 096=AVNfcst-T170/L42, 121=WesternNorthAtlanticwavemodel, 122=AlaskaWatersRegWaveModel, 130=MergeOfRucEtaSpectral.

YYMMDDHH - Year, month, date, and hour - of model start time.

A - GRIB designator - H=WAFS (Family Of Services), Y=AWIPS, Z=AWIPS.

D - Data type. X=mixture.

G - Grid. A=201 (Nhem/PS), H=213 (US/PS), I=202 (US/PS), J=203 (Alaska/PS), K=204 (Hawaii/MER), L=205 (PuertoRico/PS), M=206 (CentralUS/LAM), N=207 (Alaska/PS), O=208 (Hawaii/MER), P=210 (PuertoRico/MER), Q=211 (US/LAM), R=212 (US/LAM), T=214 (Alaska/PS), U=215 (US/LAM), V=216 (Alaska/PS), X=experimental. Code following the geographical area means PS=Polar Stereographic, LAM=Lambert Conformal, MER=Mercator.

T - Timestamp. A=00, B=06 C=12, D=18, E=24, F=30, G=36, H=42, I=48, J=60, K=72, L=84, M=96, N=108, O=120, P=132, Q=144, R=156, S=168, T=180, U=192, V=204, W=216, X=228, Y=240. However if "A" (GRIB designator) is Z (AWIPS), this will instead be A=02, B=03, C=04, D=08, etc.

Note that Digital Atmosphere will only process grids mapped in lat/long, polar stereographic, and lambert conformal projections