• Bryan Norcross

Powerful Hurricane Sam is likely to stay clear of the Caribbean islands

Confidence is now high that Hurricane Sam will avoid the Caribbean islands as the storm arcs off to the north. They might feel some outer effects on the islands around the northeast corner of the Caribbean Sea, depending on exactly how far offshore the center of Sam tracks, but the core of the storm should pass them by.



Out in the middle of the tropical Atlantic, Hurricane Sam is putting on a show. The core of the storm has consolidated into a structure with a tiny eye that should allow strengthening to continue as it crawls to the west in the general direction of the Caribbean islands. It’s already approaching Category 3, and is forecast to go the Category 4.


A temporary change in the configuration of the high-pressure system to the north will cause Sam to temporarily slow down to a leisurely stroll. The core of the high has shifted west, so it’s blocking Sam’s forward progress. But big changes in the steering pattern are coming by Monday.


A deep dip in the jet stream developing along the U.S. East Coast combined with the remnants of Tropical Storm Peter will push the high back to the east. Sam’s track is very likely to bend to the north into the gap between the jet-stream dip and the retreating high-pressure system.


Sam's slow movement turns out to be a good thing. The dip can get into place before the storm reaches the islands.


As to how close Sam will come to the islands as it turns north, the National Hurricane Center is splitting the difference between the two major computer forecast models - the American GFS and the European Center model - when it makes its cone. The European insists that Sam will ride down the left side of the cone, coming a bit closer to the northeastern Caribbean islands before the storm turns north. The GFS predicts that Sam will stay farther away.


As a rule, a compromise taking all the models into account – a so-called consensus model – is the most accurate. Most often, the cone is centered on those averaging models. That’s why, looking at individual models is never recommended. The National Hurricane Center forecast uses the most accurate forecasting philosophy.


So the cone tells us that the northeastern Caribbean islands could feel effects from Hurricane Sam, but a hard hit is very unlikely. Remember, the cone only forecasts where the center of the storm will likely track. The bad weather will extend out well beyond the width of the cone.


Looking in the long range, Hurricane Sam should travel north more or less paralleling the U.S. East Coast. It will be far to the east of Florida and the Bahamas.


When Sam gets farther north, however, Sam could come close enough to the coast to affect weather in the Northeast, New England, and Atlantic Canada. It certainly will send strong swells toward the shoreline for the last half of the week, a could produce some gusty winds. We’ll have to see how the track develops toward the end of the week.



Well to the north of Hurricane Sam and far offshore of the Mid Atlantic, Subtropical Storm Teresa formed yesterday out of a non-tropical system. It’s called “subtropical” because it’s a hybrid system with vestiges of its non-tropical roots. It’s shaped like a comma not a donut. The strong winds are well separated from the center, unlike in Sam. Mother Nature makes all kinds of weather systems.


Teresa won’t be around very long. Today or tomorrow it’s likely to get absorbed into that general low-pressure area related to the big jet-stream dip coming along.



So now we’re down to two names left on the primary list – Victor and Wanda. And it’s not even October, which historically is almost as busy as September in terms of Florida hurricane impacts. That's when systems are more likely to originate in the Caribbean or the Gulf of Mexico.


There’s a good chance Victor will get used by the next system coming off Africa. The weather pattern looks conducive for development over the eastern tropical Atlantic.


The computer forecast models hint that at least one more disturbance might come off Africa before that source of tropical systems shuts down, and of course Caribbean season hasn’t even started.


If (likely when) we go to the overflow alphabet, we’ll begin with Adria, Braylen, and Caridad.