Trans-Atlantic Crossings and the Tools Available to You
Alex Avalos, Operations Manager

It is almost that time of year again. As the winter comes to a close, many vessels will be embarking on Trans-Atlantic passages back to Europe for the start of their summer charter seasons.

Challenges can arise from such passages, as strong ridging across the Atlantic can expose vessels to strong trade winds on the nose. As the gale and cold front tracks begin to shift further north headed into the spring, further adversities can present themselves in finding the most favorable route.

Another concern that arises is the presence of cutoff gales, and given their tendencies to be further south than their non-cutoff counterparts, creative routing may need to be considered to further avoid enhanced head conditions.

This is where we come in. Our team of dedicated and experienced Meteorologists are ready to work with you to help you get across the pond, safely and comfortably. We offer you a number of tools to assist with your endeavor:

- Customized forecasting and route recommendations

- Discounted trans-ocean forecast packages

- Weather window planners

- Heavy weather alerts and tropical surveillance for your current and expected location

- Climatology studies

We at WRI look forward to assisting you with your next Trans-Atlantic voyage. Please give us a call at +1 518-798-1110, or email us at wri@wriwx.com, and our team of Meteorologists, who are available 24/7, will be happy to discuss our forecasting services and how we can make upcoming passages you have, as smooth as possible.

The Challenges of Cut-off Lows
Cara Czech, Meteorologist

As we jump into the start of spring, many vessels begin to plan their trans-Atlantic voyage to the Mediterranean during this time of year, though planning can become increasingly more challenging depending on the weather pattern. A cut-off low is an surface-level low pressure system that becomes separated from a fast-moving air river current called the Jet Stream. This weather feature often poses challenges in predicting its strength and track, especially in the long term.

To better visualize how a cut-off low develops, we can use the analogy of how Oxbow lakes (horseshoe-shaped lakes) are formed. The river current's speed is highest on the outside, where gradual erosion will occur. As the figure shows, continuous erosion gradually leads to the river cutting off a horseshoe-shaped body of water, an Oxbow lake. This natural phenomenon is similar in how cut-off lows form in the upper atmosphere. The river can be seen as the Jet Stream, which often takes shape into troughs and ridges. When a cut-off low forms, forecast models often have trouble of predicting what the outcome will be, as it is essentially pinched off from its steering mechanism where often times these systems remain stationary for days or even over a week.

 

Figure 1. Stages of the formation of an Oxbow lake. Green arrows indicate fastest waterflow and red arrows indicate slowest waterflow. Image from Prof. Stephen A. Nelson, Tulane University (https://www.geocaching.com/geocache/GC1199N)

 

Figure 2. 500mb geopotential height map displaying relative vorticity of a cut-off low developing over the SE'rn U.S. and shifts E'ward just south of Bermuda. GIF made from screenshots of Alicia Bentley Maps (https://www.atmos.albany.edu/student/abentley/realtime/)

Dependent on many environmental variables, cut-off lows can be quite unpredictable and ultimately results in difficulties regarding weather forecasting and vessel routing across the Atlantic Ocean. Cut-off lows are challenging to forecast as uncertainty regarding strength and track becomes increasingly prevalent. As this weather feature is "lost" without its driving force of the Jet Stream, models often struggle to agree with one another within the short-range, often further impacting the long range forecast. In result, this makes it rather complex when it comes to recommending best relative options, whether it's finding alternate routing for a vessel already underway or evaluating the best departure date. Generally when these systems develop, it is usually best to aim south of the cut-off low, as this assists in avoiding stronger pressure gradients and ridging to the north. However, different routing options may be better depending on the vessel's position with respect to the system and how the specific pattern plays out.

WRI monitors vessels that are underway on a daily basis, ensuring our full efforts in keeping our clients well informed and up to date on systems like cut-off lows that may impact their voyage. Contact WRI to schedule a customized forecast for your next trip.

Weather Routing to Present Webinar for Sailing and Boating, LLC.
Alex Avalos, Operations Manager

On Thursday evening, April 03rd from 06:30pm EDT, Operations Manager and Senior Meteorologist Alex Avalos will be presenting a webinar for Sailing and Boating, LLC, which will be hosted by Deb and Hugh Marlor. The first part of the discussion will entail a discussion on weather basics for boaters, including, but not limited to the drivers of weather, and the tools you can use to create a self weather briefing. The second part of the discussion will entail how you can use these tools to recognize changing weather patterns through cloud behavior, the steps you can use to prepare yourself for offshore passages and the tools available to you for monitoring the weather. This webinar is open to the public, and you can sign up for the webinar here:

We look forward to seeing you there!