Navigation and Weather – What do we use?

The following is a quick overview of what we regularly use and reference for weather routing and forecasting. The goal is to put everything in one place. As time allows, I will also be creating a low bandwidth HTML page for satellite use. Eventually, I would like to create sort of a step by step how to, which outlines our process for trip planning, navigation, and weather routing.

Feel free to bookmark it and check back.


Navigation and Weather Routing Software


Used for serious routing and planning of longer passages or races. It is much more complex than other products but gives an advanced user many tools to increase accuracy in both forecasting and polars, as well as tools to improve boat speed and VMC.

Open CPN

Open Source and Free. We started using this long before cruising but now use it rarely as a backup to Expedition. Chart Plotter and Navigational software program for use underway or as a planning tool. Developed by a team of active sailors using real-world conditions for program testing and refinement.


Used for quick weather looks and routing while underway. Updates via iridium GO fairly quickly and reliably while offshore.



We regularly consult multiple charts for any given area. Most of our plotting is done via C-Map charts and Expedition for serious navigation. Navionics on an iPad is in use during more day to day ops in known areas.


Polar File Sources

A polar diagram describes how fast a sailing boat may go at different wind speeds (TWS) and in different angles to the wind (TWA). Every type of boat has its polar diagram (or VPP, velocity prediction program), computed from hull shape, weight, rigging and a sail setup. Below are links to several locations where you may find polar files for your boat. If you can not find polars for your boat, you can build them yourself by logging your own data, or contact one of the worldwide yacht racing and rating agencies, who can provide polars along with a rating certificate at a cost.


Official Weather Links

Atlantic Hurricane 5 Day:

Atlantic Analysis:

Ocean Prediction Center:

Atlantic Weatherfax:

GEOS Caribbean:

GEOS Tropical Atlantic:

Bahamas Radar:


Other Unofficial Forecasters Links

Mikes Weather Page:

Weather Nerds:

Tropical Tidbits:


Corporate Weather Links



Predictwind Offshore – offshore weather and cloud based routing via iridiumGO

Windy – iPhone wind and forecast app

Storm – iPhone/iPad radar and forecast app

MyRadar – iPad radar

Sailflow – iPhone and web based wind

Anchor Alarm – iPpad/iPhone anchor alarm, linkable to monitor when away from boat

RD Client – view desktop PC (Expedition) on iPad over WiFi

Link – B&G app for linking MFD to iPad


Weather Model Explanations


Outlook Range: 16 Days

The Global Forecast System (GFS) is a global numerical weather prediction system containing a global computer model and variational analysis run by the United States’ National Weather Service (NWS).


Outlook Range: 6 Days

The Navy Global Environmental Model (NAVGEM) is a global numerical weather prediction computer simulation run by the United States Navy’s Fleet Numerical Meteorology and Oceanography Center. This mathematical model is run four times a day and produces weather forecasts. Along with the NWS’s Global Forecast System, which runs out to 16 days, the ECMWF’s Integrated Forecast System (IFS) and the CMC’s Global Environmental Multiscale Model (GEM), both of which run out 10 days, and the UK Met Office’s Unified Model, which runs out to 7 days, it is one of five synoptic scale medium-range models in general use.

The NAVGEM became operational in February 2013, replacing the NOGAPS. It uses the same forecast range as the NOGAPS did (three-hour intervals out 180 hours) but also uses a refurbished dynamic core and improvements to the physics simulations compared to its predecessor.


Outlook Range: 10 Days

The European Centre for Medium-Range Weather Forecasts (ECMWF) is an independent intergovernmental organisation supported by most of the nations of Europe and is based at Shinfield Park, Reading, United Kingdom. It operates one of the largest supercomputer complexes in Europe and the world’s largest archive of numerical weather prediction data.[1]

ECMWF was established in 1975, in recognition of the need to pool the scientific and technical resources of Europe’s meteorological services and institutions for the production of weather forecasts for medium-range timescales (up to approximately two weeks) and of the economic and social benefits expected from it.


Outlook Range: 3 Days

COAMPS-TC, developed by the U.S. Naval Research Laboratory (NRL) Marine Meteorology Division, is a new version of the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®) that is tailored specifically for predicting tropical cyclones worldwide (including, but not limited to, Atlantic hurricanes).


Outlook Range: 8 Days

Icosahedral Nonhydrostatic Weather and Climate Model. The ICON modelling framework is a joint project between the German Weather Service and the Max Planck Institute for Meteorology for developing a unified next-generation global numerical weather prediction and climate modelling system.


Outlook Range: 7 Days

The National Digital Forecast Database (NDFD) is a suite of gridded forecasts of sensible weather elements (e.g., cloud cover, maximum temperature). NWS field offices working in collaboration with the National Centers for Environmental Prediction (NCEP) are combined in the NDFD to create a seamless mosaic of digital forecasts. MDL contributed to the development of the NDFD and its companion project, the National Digital Guidance Database (NDGD).


Outlook Range: 1 Day

The High-Resolution Rapid Refresh is a NOAA/NCEP operational weather prediction system comprised of a numerical forecast model and an analysis/assimilation system to initialize the model. It is run with a horizontal resolution of 3 km and has 50 vertical levels.


Outlook Range: 8 Days

WaveWatch III is a third generation wave model developed at NOAA/NCEP in the spirit of the WAM wave model. It is a further development of the model WaveWatch I developed at Delft University of Technology and WaveWatch II, developed at NASA, Goddard Space Flight Center.


Outlook Range: 3 Days

The North American Mesoscale Forecast System (NAM) is one of the major weather models run by the National Centers for Environmental Prediction (NCEP) for producing weather forecasts. … The NAM generates multiple grids (or domains) of weather forecasts over the North American continent at various horizontal resolutions.


Outlook Range: 1 Day

These NCEP FNL (Final) operational global analysis and forecast data are on 0.25-degree by 0.25-degree grids prepared operationally every six hours. This product is from the Global Data Assimilation System (GDAS), which continuously collects observational data from the Global Telecommunications System (GTS), and other sources, for many analyses. The FNLs are made with the same model which NCEP uses in the Global Forecast System (GFS), but the FNLs are prepared about an hour or so after the GFS is initialized. The FNLs are delayed so that more observational data can be used.


Outlook Range: 16 Days

The Canadian Meteorological Center (CMC) produces a global computerized weather forecast model twice daily. The CMC model is global, as opposed to, the GFDL and WRF models which are regional models centered over North America. The CMC model is run through 240 hours.


Outlook Range: 3 Days

Great Lakes Only. NOAA GLERL and its partners conduct innovative research on the dynamic environments and ecosystems of the Great Lakes and coastal regions to provide information for resource use and management decisions that lead to safe and sustainable ecosystems, ecosystem services, and human communities.


Outlook Range: 8

RTOFS (Global) is a global ocean forecast system based on the HYbrid Coordinate Ocean Model (HYCOM). … Each run starts with a 2 day hindcast and produces ocean surface forecasts every hour and full volume forecasts every 6 hours from the 0000Z nowcast out to 196 hours.


Outlook Range: 7 Days

The HYCOM consortium is a multi-institutional effort sponsored by the National Ocean Partnership Program (NOPP), as part of the U. S. Global Ocean Data Assimilation Experiment (GODAE), to develop and evaluate a data-assimilative hybrid isopycnal-sigma-pressure (generalized) coordinate ocean model (called HYbrid Coordinate Ocean Model or HYCOM).

To D0:

NMEA 0183 and N2k

SSB Channels and Basics

Satellite and iridium links

B&G and 4g radar

Embed quick view recent images

Low bandwidth HTML (no WP) version

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