Hurricane Forecasts, Sausage Or Sizzle

stormpulseIt is now pretty likely that Hurricane Earl will give us high winds here on the south-western shore of Nova Scotia. However, a deviation of just 50 miles either side of the forecast track will likely make the difference between us experiencing gale force versus hurricane force winds. And that in turn will determine whether we do very little preparation on Morgan’s Cloud or a lot.

That brings me to the subject of this post: the danger of relying too much on the many sites on the internet that repackage the information generated by the US National Hurricane Center in visually appealing ways (sizzle) but in so doing, lose much of the really important information (sausage).

For example, someone living in New York with a boat in one of the comparatively open mooring fields of Long Island Sound who took a quick glance at StormPulse this morning (Wednesday), could be forgiven for assuming that he or she had little to fear from Earl.

stormpulse

But a careful read of the NHC forecast discussion for the same time yields a very different picture of the risk to that person’s boat (the emphasis is mine):

“…THE TRACK GUIDANCE IS IN GOOD AGREEMENT WITH THIS SCENARIO. HOWEVER…THERE ARE SOME SMALL DIFFERENCE IN THE MODEL GUIDANCE THAT COULD HAVE LARGE IMPLICATIONS IN TERMS OF IMPACTS

…THE GFDN…NOGAPS…AND UKMET FORECAST THE CENTER TO PASS NEAR OR OVER THE NORTH CAROLINA COAST AND NEW ENGLAND. THE OTHER MODELS ARE FARTHER TO THE EAST…KEEPING THE CENTER OFFSHORE…”

THE INTENSITY FORECAST IS A CONUNDRUM. ON THE FAVORABLE SIDE…THE HURRICANE IS OVER VERY WARM SEA SURFACE TEMPERATURES…HAS GOOD CIRRUS OUTFLOW IN ALL DIRECTIONS EXCEPT TO THE SOUTH…AND HAS A GOOD CONVECTIVE STRUCTURE. ON THE NEGATIVE SIDE…EARL IS EXPERIENCING 15-20 KT OF SOUTHWESTERLY VERTICAL WIND SHEAR…”

The point of all this is not who is right or wrong, or even what actually happens in the next few days. Rather the take-away for me is that in this modern world where we are constantly exposed to really slick ways to display data, we must also understand that by definition that very slickness can result in the loss of vital information. In this case, the forecaster’s concern that a small, and quite possible, deviation from the models could result in millions more people being exposed to the devastation of a category four hurricane.

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John was born and brought up in Bermuda and started sailing as a child, racing locally and offshore before turning to cruising. He has sailed over 100,000 miles, most of it on his McCurdy & Rhodes 56, Morgan's Cloud, including eight ocean races to Bermuda, culminating in winning his class twice in the Newport Bermuda Race. He has skippered a series of voyages in the North Atlantic, the majority of which have been to the high latitudes. John has been helping others go voyaging by sharing his experience for twenty years, first in yachting magazines and, for the last 12 years, as co-editor/publisher of AAC.

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