Available Saildocs Grib Data

"Grib" is short for "gridded binary", a data format originally used for computer forecast-model data but also used for observations (OSCAR) and forecaster-generated data (NDFD).

For general information about requesting grib data via email from Saildocs, send a blank email to: gribinfo@saildocs.com or see the web at http://saildocs.com/gribinfo

Gridded Marine Forecasts

NDFD: NDFD (National Digital Forecast Database) is a US National Weather Service (NWS) project to make forecaster-generated weather forecast data available in gridded format for the NWS areas of responsibility. These data files are prepared along with the forecast charts (radiofax charts) and text bulletins. The advantage of the grib format is a much more efficient file format (and smaller files) than chart images.

NDFD is a developing project, and available data will be expanded. Currently wind and wave data is available for the Pacific from 20S to the equator and west to 120w, equator to 30n and west to 140w, 30n to 49n and west to 133w, and offshore waters around Alaska and Hawaii. The current Atlantic coverage is 03n to 31n from the Gulf eastwards to Africa, and from 31n to 50n from the coast east to 064W.

To request NDFD data use the code "NDFD", specify the lat-lon area (respecting the available areas, above). The resolution is 0.12 deg (default is 1-deg if omitted), forecasts are available out to 7 days at 3 to 6-hour increments. Files are currently updated by 01:00z (for the 00z forecast), then 07:00, 13:00, 19:00 and 23:00z.

Currently available parameters are WIND,GUST,WAVES.

A typical request would be:
send NDFD:26N,20N,114W,105W|0.25,0.25|12,24..72
(Roughly Cabo to Puerto Vallarta, 0.25 deg grid, every 12 hours out to 3 days, about 12KB).

NDFD is still in "experimental" status which means that the data may not be available or correct (which is always true for computer data).

For more info about the NDFD program see:

Computer Forecast Models in Grib format:

The primary source for Saildocs computer-model data is NOAA's "GFS" global model, requested by using the code "GFS:" (or "Grib:") in a grib-request. Data from other models is also available. Here are the details for the available models:

The most-often used model is NOAA/NCEP's global "GFS" (Global Forecast System) model. The model is run avery 6 hours and complete data is usually available by 05:00, 11:00, 17:00 and 23:00 utc for the 00, 06, 12 and 18z model-runs (i.e. HH+5hrs).

Data for 0-96hr forecast times is available an hour earlier (04:00 etc). Use the same "GFS" code, Saildocs will select the "early" file if the request is limited to 0-96hrs, otherwise data from the previous model-run will be provided until 05:00.

The request-code is "GFS:" as used in the examples in the "gribinfo" document. The accompanying message will identify the cycle and time that the files were downloaded from the NOAA servers.

Currently available parameters are:
PRMSL (PRessure/Mean Sea Level, smoothed-- SEE NOTE BELOW)
MSLP (unfiltered Mean Sea Level pressure)
WIND (10 meters above surface)
GUST (at 10 meters)
AIRTMP (temperature 2 meters above surface)
SFCTMP (temp at surface)
RH (Relative Humidity 2m above surface)
LFTX (LiFTed indeX)
CAPE (Clear Air Potential Energy)
RAIN (Precip rate, mm/hr)
APCP (Accumulated precip)
HGT500 (500mb height)
TMP500 (temperature at 500mb level)
WIND500 (Wind velocity at 500mb level)
ABSV (Absolute vorticity at 500mb)
CLOUDS (Total cloud cover)
Also WAVES can be added to include significant wave height from the WW3 model.

NOTE: PRMSL data from the GFS model is actually filtered (smoothed) data. This is an oddity of GFS, the effect is smoother isobars but it also tends to hide interesting details (steep troughs, fronts, etc.) Unfiltered data is available by specifying MSLET or MSLP.

Data is currently available as follows:
0-120 hours every 3 hours on a 0.25 x 0.25-deg grid;
123-192 hours every 3 hours on a 0.5 x 0.5-deg grid;
198-240 hours every 6 hours on a 0.5 x 0.5-deg grid;
252-384 hours ever 12 hours on a 1.0 x 1.0-deg grid.
Note, however, that forecast accuracy becomes increasingly speculative after 4-6 days.

A typical request could be:
send GFS:26N,20N,114W,105W|0.25,0.25|0,6..72|WIND,PRMSL,WAVES

The "GRIB" code can also be used, the difference is that for "grib:" the forecast-times are always adjusted to provide forecast-times relative to 00z. Available parameters are PRMSL,WIND,HGT500,TEMP. Data is almost always available by HH+05:00 hours ("HH" being the synoptic-time), so by 05:00z for the 00z forecast cycle.

NOAA is in the process of updating the core of the GFS model. The new version is running in parallel experminetally, and is available with the code "FV3GFS". Parameters and details are the same as the operational GFS model although it is currently running about 3 minutes later and no "early" data is available. Once the FV3 update becomes operational the GFS and FV3GFS codes will both access the new version. This is expected around Mar 10, 2019 but may be further delayed.
See https://www.weather.gov/news/fv3 for more info.

ECMWF "WMO Essential":
The European ECMWF model data is highly regarded but not available for distribution without prohibitive fees. There are however a few parameters available as "essential" data to meet WMO obligations-- surface pressure and 500mb height, basically. While only marginally useful for offshore sailors, this data can provide a useful reference for GFS or another model data.

The code is "ECMWF", default parameters are surface pressure and 500hPa height (MSLP,HTG500). Temperature and wind and 850 hPa (TMP850 and WIND850) are also available. The grid is 0.5 x 0.5 deg, forecasts are available from 00 to 240 hours (10 days) at 24-hour increments and updated twice a day,and generally available by 07:00 and 19:00 utc.

This is the US Navy model formerly known as NOGAPS, with data available on a 1-deg grid with forecasts every every 3 hours to 24, then 6 hours to 96, then 12 hours to 144, and updated every 6 hours by HH+06:00. Available parameters are PRMSL,WIND,HGT (the default is PRMSL,WIND). The general view is that GFS has better accuracy on average, but Navgem is an independent model and is valuable as a "second opinion".

This is a meso-scale (i.e. more detailed) regional model provided by the US Navy. Data is available for three regions: eastern Pacific, west Atlantic, and Carib/Central America. The syntax is the same as for a basic grib, except the request-code "coamps:" is used in place of "gfs:" or "grib:".

For the four US coastal areas, forecast data is available on a 0.15 x 0.15-deg grid at 3-hour intervals out to 96 hours (except 72 hrs for w-Atl). Available (and default) parameters are WIND. The euro model is 96 hours at 6-hour intervals for pressure and wind.

The areas for the currently available coamps areas are:
NE Pac: 34n,64n,172w,118w
So Cal: 22n,43n,128w,109w
Eq. Am: 12s,32n,122w,058w
W Atl: 20n,55n,093w,055w
Euro: 29n,66n,015w,040e

The same "coamps:" code is used for all regions, and Saildocs chooses the appropriate region based on the requested lat-lon area. Requests which fall partially outside the selected region will be trimmed at the edge of the region, and a zero-length file will result if the request is completely outside any of the regions. It is not possible to span multiple regions because data from different files does not match at the region edges, apparently a boundary-condition limitation with the model.

"High Resolution Rapid Refresh" is a NOAA hi-res forecast at one-hour increments and updated hourly, primarily covering Continental US but does spill into the coastal waters-- very roughly east of a line from 24N 123W to 48N 133W in the Pacific, and 23N 074W to 48N 063W in the Atlantic.

To see the full extent of coverage, send this grid request to query@saildocs.com (about 18KB):
Send HRRR:55N,20N,140W,060W|0.5|0|WIND

Maximum resolution is 0.03 x 0.03 deg (around 2 miles) but care is needed: With large areas, high resolution and one-hour increments files can easily get huge.

The hourly update is available out to 18 hours, available at HH+1.5 hours (e.g. the 00z update cycle is available at 01:30 utc). There is also a model run every 6 hours which extends to 36 hours, available at hHH+2.0 (e.g the 00z model run is available at 02:00 utc). Saildocs will select the hour update for requests out to 18 hours, and will select the 6-hourly run (even if older data) if the requested forecast times are greater than 18 hours. So for more-recent data, limit forecast times to 18 hours max. For longer forecasts, understand that the data will be the previous six-hourly run. The model run is always part of the file-name listed in the reply-message.

Available parameters are:
PRMSL (pressure at sea level)
WIND (10 meters above surface)
GUST (10 meters)
AIRTMP (temperature 2 meters above surface)
SFCTMP (temp at surface)
LFTX (Lifted index)
CAPE (clear air potential energy)
RAIN (Precip rate, mm/hr)
APCP (Accumulated precip)

A sample file could be this, sent to query@saildocs.com (about 35KB):
send HRRR:35N,31N,122W,116W|0.2,0.2|0,1..18|WIND

This is NOAA's WW3 wave model, data is available on a 1 x 1.25 grid (lat x lon), forecasts every 3 hours out to 180, updated every 6 hours usually by HH+05:00 (5 hours after the synoptic time, or 05:00 for the 00z forecast). All of the WW3 data is available, the default parameter is "HTSGW" (height of sig waves) or "WAVES", other WW3 parameters are WVHGT (wind-wave height), WVPER (wind-wave period), WVDIR (wind-wave direction), PERPW (period of primary wave), DIRPW (direction of primary wave), PERSW (period of secondary wave), DIRSW (direction of secondary wave), WIND (GFS wind, the primary model input).

Also, the "WAVES" parameter can be added to a GFS request and Saildocs will combine the files, adding the WW3 sig-wave data layer to the same grib file (on the 1x1.25 grid if coarser than the user-specified grid).

Regional WW3 models are also available, updated every 6 hours and available around HH+05:00, as follows:
ww3akw: 45n,75n,160e,123w 0.3 x 0.5 deg grid, to 180 hrs @ 3 hr increment
ww3enp: 05n,60n,170w,070w, 0.3 x 0.25 grid, to 180 hrs @ 3 hr inc
ww3wna: 00n,50n,098w,030w, 0.3 x 0.25 grid, to 180 hrs @ 3 hr inc
ww3euro: 29n,66n,015w,045E, 0.2 x 0.2 grid, to 96 hrs @ 6 hr inc
The first three are also available as "ww3merged" to allow spanning Central America.

If the generic "WW3" code is used (or "Waves" added to a GFS request) then then Saildocs will choose the best data file for each request, i.e. whichever returns the most data points. The code WW3global can be used to force the global ww3 model.

This is an ocean current forecast model from NOAA's RTOFS system, based on the HYCOM model (see http://polar.ncep.noaa.gov/ofs/ for more details). It was previously two different models and three overlapping areas (gulf-stream, Atlantic and Global) but now consolidated into a single global model available with the code "RTOFS". The resolution is 0.08 (1/12) deg, and is currently available out 72 hours as daily forecasts (24-hour forecast increments) or 3-hourly files (3-hour forecast increments), and generally available by 12:00z.

A second model run provides forecasts beyond 72 hours, out to 192 hours (8 days). This is available as daily forecasts (24-hour forecast increments) or 3-hourly forecasts (at 6-hour forecast increments), and generally available by 18:00z.

Note that the daily and corresponding 3-hourly forecasts (e.g. 24 hours) won't exactly match due to differences in averaging (3 hours versus 24). Saildocs will select whichever dataset best satisfies the requested forecast times, even if that is older data. The model run is always part of the file-name listed in the reply-message: "rtofs" is daily forecast data out to 72 hours, "rtofsx" is daily out to 192 hours, "rtofs3" is 3-hourly out to 72, and "rtofs3x" is 3-hourly data to 192. Saildocs does the selection, the "RTOFS" code an always be used.

Available RTOFS parameters are CURRENT (or CUR or UOGRD,VOGRD), WTMP (or WATER_TEMP), DSL_M (sea-level deviation), and SALTY (salinity). The default (if parameters are omitted) is CURRENT.

"Ocean Surface Current Analysis- Realtime" is an ocean current analysis based on satellite observations (scatterometer and altitude) over a 5-day period, and updated every 5 days. Resolution is 0.33 deg, global data is provided but the focus is on the tropical Pacific. The code is "OSCAR", the forecast-time field is not used, and the default (and only) parameter is surface current (CURRENT or UOGRD,VOGRD).
For more info see http://www.oscar.noaa.gov when internet is available.


To receive an updated copy of this document whenever changes are made, send the following one-line request to: query@saildocs.com

subscribe gribmodels days=365

(The "days" parameter indicates the time that Saildocs will check for changes: "365" means one year, "0" means indefinitely).

To get general info about Saildocs send a (blank) email to: info@saildocs.com (auto-responder)

For problems/questions relating to Saildocs, send an email to: support@saildocs.com

Thanks for using Saildocs and Good Sailing!
(updated 2019-02-24 jec)