Weather

Sources of weather and oceanographic data

The data referenced below is available from Expedition, Saildocs, Great Circle-Squid or Tidetech. These are all integrated into 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.

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 links to freely available observation and model data (MyGrib and MyImage). Expedition also has a grib server, provided as a backup to Saildocs and Squid. Expedition also supports services such as Ocens.

Important note

Whilst racing, weather data or services such as routing that are 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 and satellite images 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 such as Iridium. For Iridium GO, the recommended solution is to use AirMail or SquidX as downloads can be long.

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.

GFS

13km resolution and 64 levels, increasing to 127 levels with GFS16 in March 2021,
Available 4x daily at 1/4° or 1/9° resolution,
NOAA USA.

UM-Global

10km resolution and 70 levels,
Available 4x daily at about 1/10° resolution,
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-Global,
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,
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

TWC

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 & currents

SailFlow

Expedition has integrated current models for various areas.

Reanalysis

Copernicus
ECMWF