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Weather Challenges on a Fall Passage South



by Andy Schell

A fall passage to the Caribbean from the northeast US is undoubtedly one of the more challenging offshore undertakings, both once at sea and indeed during the preparation stages. Here at the Caribbean 1500 headquarters in Portsmouth, VA, we write about the weather every year – about how difficult it is to find a weather window this time of year, as we’re squeezed between the winter gale season and the end of tropical cyclone season.

We thought it useful to provide some insight into how and where we get the weather info we use for planning purposes and what goes on behind the scenes. I always look at the rally departure as a skipper, not an event manager – meaning, I’m looking for weather patterns that I’d feel most comfortable departing in if I were actually sailing (and I actually am this year!), but also taking into account the varied experience of the fleet.

So, in the bigger picture, what weather patterns do we look for?

One challenge of leaving from the northeast is the Gulf Stream crossing (though it’s not nearly as big a deal as some people make it out to be – IF you leave in the right weather conditions). Logic would dictate departing on a southwesterly wind – wind with the flow of the current, which sets to the NE. BUT, a southwesterly wind this time of year often indicates an approaching cold front. The interaction of this especially cold air moving out over the much warmer water of the Gulf Stream creates volatile localized weather, meaning increased wind, thunderstorms, rain and otherwise lousy conditions. Fronts can stall over the stream and intensify even further. This is what plagued the Salty Dawg rally a few years back (though their troubles were more down to not being prepared for those escalating conditions, which in reality weren’t that bad).

Anyway. I like to depart, and look for a window for the rally to depart, just AFTER the passage of a cold front. The weather clears, the incoming High pressure creates a more stable, fair-weather pattern, and the wind, which starts in the west and quickly veers around to east-northeast, is from behind, making for reaching to broad-reaching conditions. However, especially this time of year, it’s usually a strong wind from the northerly quadrants, so you’ve got to be ready for 20-25, sometimes 30 knots of wind coming over the quarter. It’s a baptism by fire sometimes, but makes for fast sailing.

The real challenge is timing the departure so that you can get across the axis of the Stream before the wind goes all the way into the NE and E. Even a 25-knot wind from the northeast is not a real problem in the Stream. Yes, it’s wind against current, but not enough wind to be dangerous. It’ll be bumpy, for sure, but there’s a difference. And, due to the incoming High, even a strong northeasterly wind will normally blow itself out in a few days as the High drifts farther offshore.

Sometimes the incoming High interacts with the outgoing Low and causes steep High-pressure ridging over an area just offshore. The pressure gradient gets tight, and the wind can blow hard for days from the NE and E. This can make the Gulf Stream uncomfortable, but furthermore can hinder progress to the east. Generally, sailing directions dictate getting east early, while you’re still up north, to setup for the run south once into the Trades. If you miss it, you’ll be close-hauled for almost half the passage, once you’re into the Trades, and wind up with an easier sail to Puerto Rico than to the BVI!

The other factor of course is tropical weather. You’ve got to keep it in perspective though – any forecast is merely a mathematical model based on current atmospheric conditions. But any action in the tropics is a big NO GO for any prudent skipper. 

Stay tuned as the weather develops between now and Sunday's planned start!

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Free Online Weather Sources

• National Hurricane Center: nhc.noaa.gov
• Coastal & Offshore Text Forecasts: nws.noaa.gov
• Interactive Wind & Currents Globe: earth.nullschool.net
• Global Sailing Weather (Wind & Currents): globalsailingweather.com
• Saildocs (subscribe to receive GRIBS offshore): saildocs.com
• ZyGRIB: GRIB reader for Apple (search online)
• PocketGRIB: Smartphone App (search in app store)

Besides the standard sources of weather available free and online to anyone, we work closely with Weather Routing Inc. (WRI) to determine a good weather window, and we use their text forecasts for the rally fleet once everyone gets offshore (a big benefit of the 1500).