Weather

Sources of weather and oceanographic data

The data referenced below is available from Saildocs, Great Circle-Squid, Tidetech 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, especially for US and European waters.

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

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

SailFlow is a source of weather observation data.

Tidetech is a source of specialised oceanographic and tidal data.

Expedition has an integrated grib server, mainly to provide data not available from Saildocs or Squid. For example, GFS 1/9°, UM-Global and NBM Oceanic.

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

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. However, 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 and Squid.

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

Windy may be the best of the online weather viewers, with GFS, ICON, ECMWF, Arôme & NAM data. It is also available as Android and Apple apps. Flowx is another very nice app and includes Expedition WRF data.

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

Comparing models is difficult - generally the important considerations are timeliness and which is performing best on any day. Model Accuracy can be useful to compare how different models performed during a race or at a given location. Of course past performance isn't always a good indicator of future performance.

NBM

National Blend of Models - a blend of many models
Available 4x daily at 0.06° resolution (NBM Oceanic)
NOAA USA

GFS

13km resolution and 127 levels
Available 4x daily at 1/4° or 1/9° resolution
NOAA USA

UM-Global

Powered by Met Office Data
10km resolution and 70 levels
Available 4x daily at about 1/10° resolution. 06 and 18z runs are only available to 60 hours
UK Met Office

ICON

13km resolution and 90 levels
Available 4x daily at 1/4° or 1/8° resolution. ICON data is generally available earlier than GFS and UM
DWD Germany

GDPS

15 km resolution and 84 levels,
Available twice daily at 0.24° or 0.15° resolution
Environment and Climate Change Canada, licence terms

Arpège

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

ECMWF

9km resolution
Available 4x daily at 0.1° or 0.2° resolution
Expensive and available later than GFS, ICON or UM

NAVGEM

T681 (about 20km) and 60 levels
US Navy model

NEMS

39km resolution and 60 levels,
Available at 1/10-1/2° resolution
Meteoblue Switzerland

RTOFS

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

Mercator

Current model
ECMWF

WW3

Wave model
NOAA USA

Regional models

The 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

RDPS

Cape Town

Expedition WRF

Caribbean

NOAA HRRR, RAP & NAM
Arôme
Expedition WRF

Europe

Arôme & Arpège
HIRLAM & Harmonie, FMI, KNMI & YR.no
ICON EU & CosmoDE
Lamma
SMHI Sweden
Expedition WRF, some areas are on demand for regattas
BSH Baltic & North Sea tidal currents

Expedition has integrated current models for various areas, including Proudman European tidal currents and SHOM tidal currents for France

Japan, Hong Kong, Philippines

Expedition WRF, on demand
Hong Kong tidal current data

New Caledonia and Polynesia

Arôme

NZ

Expedition WRF

USA

NOAA HRRR, RAP & NAM. HRRR is very good
GLERL - Great Lakes winds and currents
SailFlow
Expedition has integrated current models for various areas

Reanalysis

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