Weather

Sources of weather and oceanographic data

The data referenced below is available from Saildocs, Great Circle or Expedition. These are the main sources of data used by the sailing community and are all available in Expedition. In addition, much data is feely available on the internet.

Expedition

Data available includes:

GFS, UM, ICON, ECMWF HRES & Ensemble, GDPS, Arpège, NBM,
Arome, HRRR, ICON-EU, ICON-DE,
Copernicus Mercator, OFS.

Expedition also supports several other services and has links to freely available observation and model data (MyGrib and MyImage).

Saildocs

Saildocs is a free source of grib data designed to satisfy Rule 41(c) and can be used to retrieve other information.

Great Circle - Squid

Great Circle - Squid is a complete weather service with satellite images, observations and model data
Offical supplier to the Volvo Ocean Race.

Important note

Whilst racing, services such as routing or weather data that is not free of charge or easily available to all boats are not allowed by Rule 41(c) (outside help) of the RRS. See Case 120 in the Case book.

Case 120 clarifies that rule 41c may be changed for any particular race by the notice of race and sailing instructions.

Weather maps and observations

Weather maps, satellite and radar imagery are available from many sources, including MyImage in Expedition, Rainviewer and Squid.

Weather observations are available from many sources, including BOM, NOAA NDBC and SailFlow in Expedition.

Rainviewer

Global Rainviewer radar data
Integrated into Expedition
Rainviewer is a free service, so we encourage people to support them with Patreon

Sailflow

SailFlow is a source of weather observation data
Integrated into Expedition

Flowx

Flowx is a very nice app and includes Expedition WRF data

Windy

Windy may be the best of the online weather viewers

Ensemble forecasts

Ensemble forecasts are used to help understand uncertainty in forecasts

Ensemble forecasts consist of an unperturbed control run and a set of perturbed members, in which the initial conditions and model physics are perturbed from the control run.

On average, each of the perturbed members will have lower skill than the control or deterministic forecast, although any individual forecast might show a higher skill.

Grib data

Data and sources we have found useful over many years of racing:

Global models

From experience, 0.25° is a good compromise for global model data offshore

0.5° is usually too coarse, but is an option for slow connections.

1/8°-1/10° data may be more useful, but file sizes will be larger. Doubling the resolution will increase file size by about a factor of 4

The Expedition server update status can be queried from within Expedition.

Availability
00z 06z 12z 18z
ICON 0310 0910 1510 2110
GFS 0410 1010 1610 2210
Arpège 0400 1045 1530 2245
GDPS 0430 1630
UM 0450 1050 1650 2250
ECMWF 0710 1310 1910 0110
ECMWF Ensemble 0810 1410 2010 0210
NBM 0150 0850 1350 2050
Mercator 1000
GFS

Available 4x daily at 1/9° or 1/4° resolution to 384 hours
13km resolution and 127 levels
GEFS is the GFS ensemble forecast system
NOAA USA

UM

Available 4x daily at about 1/10° resolution
00 & 12z runs are available to 168 hours, 06 & 18z runs to 60 hours
10km resolution and 70 levels
UK Met Office - Powered by Met Office Data

ICON

Available 4x daily at 1/4° or 1/8° resolution
00 & 12z runs are available to 180 hours, 06 & 18z runs to 120 hours
13km resolution and 90 levels
ICON data is generally available earlier than GFS and UM
DWD Germany
Licence and copyright

ECMWF HRES

Available 4x daily at 0.4° resolution
00 & 12z runs are available to 240 hours, 06 & 18z runs to 90 hours
9km resolution and 137 levels
The ECMWF Ensemble forecast consists of a control and 50 perturbed members.

Licence and copyright

  1. Copyright statement: Copyright "© European Centre for Medium-Range Weather Forecasts (ECMWF)".
  2. Source www.ecmwf.int
  3. Licence Statement: This data is published under a Creative Commons Attribution 4.0 International (CC BY 4.0). https://creativecommons.org/licenses/by/4.0/
  4. Disclaimer: ECMWF does not accept any liability whatsoever for any error or omission in the data, their availability, or for any loss or damage arising from their use.
  5. Where applicable, an indication if the material has been modified and an indication of previous modifications.

GDPS

Available twice daily at 0.15° resolution to 240 hours
15 km resolution and 84 levels
Environment and Climate Change Canada, licence terms

Arpège

Available 4x daily at 1/2° resolution globally and 1/10° for Europe
Available to 60, 72, 102 or 114 hours depending on run
7.5-37km resolution and 105 levels,
Meteo France
Licence

NAVGEM

T681 (about 20km) and 60 levels
US Navy

NBM

Available 4x daily at about 10km resolution (NBM Oceanic)
NOAA USA National Blend of Models - a blend of many models
Currently disabled as I don't believe it adds value

Regional models

Local government high resolution models are generally very good and are usually the default choice

Expedition also provides WRF simulations for areas where high resolution data is not available or hard to obtain. They can be also useful as a second forecast for comparison.

Australia

BOM Access
Expedition WRF

Canada

HRDPS

Cape Town

Expedition WRF

Caribbean

HRRR
NAM
Arome
Expedition WRF

Europe

Arome, updated 3 hourly (licence)
HIRLAM
Harmonie
ICON EU
ICON DE
Lamma
Expedition WRF

Japan, Hong Kong, Philippines

Expedition WRF
Hong Kong tidal current data

New Caledonia and Polynesia

Arome

NZ

Expedition WRF

USA

HRRR
NAM
SailFlow

Oceanography

Mercator

Copernicus Marine Environment Monitoring Service (CMEMS)
Global ocean currents available at 1/12° resolution
Higher resolution data available for north west Europe and the Mediterranean

Licence and attribution

  1. Licence
  2. Global ocean analysis and forecast
  3. Mediterranean Sea analysis and forecast
  4. Atlantic - European North-West European Shelf analysis and forecast

RTOFS

Ocean currents and sea temperature, available at 1/12° resolution
NOAA USA

GFS

Wave model
NOAA USA

OSF - NOAA Operational Forecast System
BSH

BSH Baltic & North Sea tidal currents

Tidetech

Tidetech is a source of current and tide data

Expedition integrated current models

Proudman European tidal currents
SHOM tidal currents for France

Reanalysis

Copernicus
Copernicus ERA5 hourly data on single levels from 1979 to present
ECMWF