Weather

Sources of weather and oceanographic data

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

All the main global and regional weather models. Also WRF simulations for various venues.

Saildocs

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

Squid

Squid is a complete weather service with satellite images, observations and model data.

Sailflow

SailFlow is a source of weather observation and model data.

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.

Some data from the Exp grib server (UM, UKV, Access) is only available to registered Expedition users.

Weather maps and observations

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

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

ASCAT

ASCAT Observation data in GRIB format, available from the Exp grib server.
EUMetSat and KNMI.

Rainviewer

Rainviewer global radar data. Integrated into Expedition.

Windy

Windy may be the best of the online weather viewers.

Flowx

Flowx is a very nice app that includes Expedition WRF.

Ensemble forecasts

Ensemble forecasts are used to help understand uncertainty in forecasts.

Ensemble forecasts consist of a control run and a set of ensemble runs, in which the initial conditions and/or 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.

ENS is available from Expedition and GEFS is available from Great Circle.

Grib data

Data we have found useful over many years of racing:

Global models

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

0.5° is usually too coarse, but is an option for slow connections,
0.1° data may be more useful, but file sizes will be larger,
Doubling the resolution will increase file size by about a factor of 4.

Most model data is available 3-4 hours after the main synoptic hours.
ICON is generally available first, followed by GFS, UM and the others.
EC HRES is the last available as it is a medium range model (the M in ECMWF).
See the approximate availability table below.

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

UM-Global

10km resolution
Updated 4x daily at 0.1° resolution to 60 or 168 hours
UK Met Office

GFS

13km resolution
Updated 4x daily at 0.1 or 0.25° to 384 hours
NOAA

ICON

13km resolution
Updated 4x daily at 0.1° resolution to 120 or 180 hours
DWD Germany

GDPS

15km resolution
Updated twice daily at 0.15° resolution to 240 hours
Environment Canada

Arpège

7.5-37km resolution
Updated 4x daily at 0.25° resolution to 60, 72 or 102 hours
Météo France

ECMWF HRES

9km resolution
Updated 4x daily at 0.25° resolution to 90 or 240 hours
ECMWF

Availability

Regional models

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

Expedition also provides WRF simulations, mainly for sailing venues where high resolution forecast data is not available.

Oceanography

Copernicus

Copernicus Marine Environment Monitoring Service (CMEMS)
Mercator global ocean currents available at 1/12° resolution
Higher resolution data available for North West Europe (NWS), Mediterranean and Iberia to Ireland (IBI)

Mercator global ocean
Mediterranean Sea
Atlantic - European North-West European Shelf
Atlantic - Iberian Biscay Irish
Baltic Sea

RTOFS

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

GFS

Wave model
NOAA USA

OSF - NOAA Operational Forecast System
BSH

BSH Baltic & North Sea tidal currents

Barotropic

Barotropic is a source of current and tide data for France

Current Lab

Current Lab is a source of current and tide data

Tidetech

Tidetech is a source of current and tide data

Expedition integrated current models

Reanalysis

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

Licences and copyright