Gulf Stream & WX
For more than 40 years, Frank Bohlen has studied ocean and nearshore currents and transport. Since 2002 he has prepared detailed analyses of the ocean between Newport and Bermuda in the months prior to this race.
Racing success as well as an enjoyable and safe passage to and from Bermuda requires care in preparation. To assist in this process the Bermuda Race Organizing Committee provides a variety of resources including the Ambassadors and Inspectors directed particularly at boat, crew and logistics issues.
Of course, of equal, if not more, importance is the range of weather, current and sea state conditions that might be encountered during the passage. Too often skippers and navigators fail to give these critical factors the personal attention they deserve relying instead solely on professional services to provide a basis for optimum routing. Experience indicates however, that the value of professional services would increase significantly if clients had been better prepared to evaluate the information provided. Such preparation would also reduce the potential for “surprises” during the passage at which time the professionals are not available for consultation.
To assist in the analysis of probable weather and Gulf Stream conditions that will be encountered during the race to Bermuda and the return trip home I have compiled a list of what I consider to be websites of particular value considering both content and the possibility that the data provided could be compressed for easy download offshore via a satellite phone. Some number of the sites include explanatory material or tutorials that should not be overlooked. In the case of weather, analyses might be advanced by participation in a short course or webinar available from a number of sources.
For the Gulf Stream, I will again be preparing a number of tutorials (archives since 2002 below) dealing with the structure and location of the Gulf Stream during the time preceding the start. Typically these extend over a one to two month period depending on the extent of the cloud cover and the complexity of the Stream. For both weather and Gulf Stream it is advisable to start analyses at least one and preferably two months prior to the start so as to have sufficient time to look over conditions encountered in previous races and to avoid the difficulties that are sure to arise if one begins study a week before the start! I hope that you will find this range of information useful and invite you to add your own preferences. Please don’t hesitate to contact me if there are any questions.
The National Weather Service site and the Ocean Prediction Center site both have an abundance of products including marine forecasts and satellite imagery. Valuable resources for the study of weather. Look particularly at the NWS Ocean Prediction Center and their Probabilistic Guidance. These sites must be studied!
Home of the Euro model. Comparisons of the forecast provided by this model to those provided by the U.S. GFS model in combination with observed conditions can increase confidence in model products.
A site maintained by Rutgers University which includes a variety of satellite data specific to the Gulf Stream. Also see the coastal current data provided by CODAR . These latter data will be of value to those transiting the Jersey shoreline. Similar data are available at https://lisicos.uconn.edu / for the area off Montauk Point. Entry to the Rutgers site may be confusing at first. From the main menu enter Data, next under satellites select satellite data to get to the imagery. There select Gulf Stream and specify the dates of interest. Images are instantaneous pictures of conditions. The classic view remains available at https://marine.rutgers.edu/cool/sat_data/?product=sst®ion=leo¬humbs=0
This site provides modeled currents based on satellite altimeter data. Although application requires care (View HELP) these model results allow analysis of Gulf Stream conditions during times when cloud cover prevents direct observation of sea surface temperature characteristics. Several model results are presented requiring study to assess navigational utility. Comparison with surface thermal data (e.g. Rutgers above) and any direct observations of surface currents is recommended. (Requires JAVA on your computer. Acquisition might also depend on browser. Internet Explorer on Windows 10 works today).
The National Weather Service’s Environmental Modeling Center and home to the Global Real Time Ocean Forecast System model (RTOFS). Since some routing software uses this model it’s useful to compare model results to direct satellite observations to develop confidence in model simulations. This model provides 1/12 degree resolution and is the result of collaboration between NOAA and the U.S. Navy Research Laboratory and others.
This is the current site for the U.S. Navy ocean features/ Gulf Stream analysis. Although the accuracy of this analysis must be carefully evaluated by comparison with satellite imagery and altimetry its regular updating during periods of dense cloud cover makes it of value in planning. The colorized version can be found at https://www.ncei.noaa.gov/jag/navy/data/satellite_analysis/gsncofa.gif?id=75957
Another site to obtain the results of the collaborative between the Navy and NOAA. Both use the HYCOM model. Interesting to compare results. See time series (e.g for SST “Last 30days (gif)”)
Bermuda Weather’s site. Provides continuing weather analyses and forecasts for the immediate vicinity of the island. It’s often interesting to compare these forecasts to those provided by the U.S. NWS using the GFS model and those provided by the European service ECMWF using the Euro model. In particular, see Yacht Charts under Marine Forecast as well as tidal data for Bermuda.
This product from the Ocean Prediction Center showing average sea surface temperatures over 4 days is a good way to monitor Gulf Stream evolution
The source for Canadian weather and sea state analyses and forecasts. . See https://weather.gc.ca/model_forecast/wave_e.html for wave analyses.
These data allow direct confirmation of wind speeds and directions provided by the Surface Analyses from the National Weather Service and the variety of GRIB model data. The scatterometer data are often particularly useful in the vicinity of the Gulf Stream. This system represents the alternative to our QuikScat which is no longer operational.
A listing of tidal elevations and tidal currents at a number of stations throughout the U.S. Particularly useful for coastal and nearshore passages
For those wishing to look at the conditions during previous races this provides an archive of the NWS data back to the 1950s.