Gulf Stream & WX

Frank Bohlen

Frank Bohlen, BROC Weather & Gulfstream Advisor

​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 Committe 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.

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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 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. Enjoy !

Thanks to Commanders’ Weather for their in-kind donation of specialized weather forecasts for the duration of the 2014 race.

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Weather and Gulfstream Resources

Gulf Stream Tutorials

Frank Bohlen has been observing and studying the waters between New England and Bermuda for decades, with a particular focus during Bermuda Race Years.

Visit Frank’s
Gulf Stream Tutorial Archive.

National Weather Service


noaa

www.nws.noaa.gov

The National Weather Service site with an abundance of products including marine forecasts and satellite imagery. A valuable resource for the study of weather. Look particularly at the NWS Ocean Prediction Center sites. Check out the film loops at this site. The place to start !

NWS Environmental Modeling Center

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http://polar.ncep.noaa.gov

The National Weather Service’s Environmental Modeling Center and home to the Real Time Ocean Forecast System model (RTOFS). Although this model’s resolution is a bit coarse, covering for example most of the North Atlantic, its looping capabilities assist in the determination of how fast some ocean current features evolve. In addition this site allows comparison of model results to satellite data and other models such as those developed by the Navy.

For particularly interesting comparisons see opc.ncep.noaa.gov/GlobalOceanStart.shtml.

Rutgers University Coastal Ocean Observation Lab

rutgers

rucool.marine.rutgers.edu

A site maintained by Rutgers University which includes a variety of data specific to the Gulf Stream. Drift buoy data and satellite imagery are of particular interest. Comparisons between these data and the thermal images available from the Naval Oceanographic Office is often interesting and instructive. 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 LISICOS.uconn.edu for the area off Montauk Point. Entry to the site may be confusing at first. From the main menu enter Data to find the Real time and Archived Satellite Imagery of the Gulf Stream. Note that there are both instantaneous and daily composite files.

Navy Ocean Features Analysis

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ecowatch.ncddc.noaa.gov/

This is the current site for what in past years was the U.S. Navy ocean features 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.

Johns Hopkins Ocean Remote Sensing

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http://fermi.jhuapl.edu/sat_ocean.html

A site maintained by Johns Hopkins University providing links to a variety of satellite imagery and altimetry data. The combination is sometimes able to provide a unique indication of the presence of a Gulf Stream warm or cold core ring. An additional means to analyze Gulf Stream features if carefully applied.

NOAA Real Time Altimeter

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http://www.aoml.noaa.gov/

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 periods during which 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 such as those provided by drifters is recommended.

Bermuda Weather


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http://www.weather.bm

Bermuda Weather’s site. Provides continuing weather analyses and forecasts for the immediate vicinity of the island. It’s often interesting to compare these observations to conditions indicated by the larger area weather maps such as the NWS weatherfax charts of the northwest Atlantic. Also, see Yacht Charts under Marine Forecast as well as tidal data for Bermuda.