The future path of Tropical Storm Ian remains highly and exceptionally uncertain
Updated at 8:15 a.m. Eastern Time
Tropical Storm Ian continues to organize in the Caribbean Sea south of Jamaica. There are now no obvious external factors limiting it, so the organizing process is expected to end today and a rapid escalation process to begin this evening.
The National Hurricane Center predicts that Ian will be a powerful, possibly Category 3 hurricane when it approaches western Cuba late tomorrow.
There is general agreement between the different computer prediction models on this part of the trajectory. There is a slight east-west spread from Cuba to the western end of the island, but this is normal.
On Wednesday, however, the differences in forecasting patterns are profound. Essentially, some models pick up the storm on the left side of the cone well off the coast of Florida into the Gulf of Mexico and into the Panhandle. Other models have the hurricane track down the right side of the cone and curve it toward the west coast of Florida.
As different as they are, both tracks are believable.
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Ian should be a category 4 monster as he enters the gulf. As it continues north, there is good agreement among the longer range predictions that the upper level environment will become more hostile, and Ian will weaken. The unresolved question is whether the system latches on to the right and lands like a mighty storm before the environmental regime changes. Does the attenuation occur over the ocean or over the Florida peninsula? It is unknown.
And very importantly, if the storm weakens over the gulf, it will grow larger and still produce a life-threatening storm surge on the Florida gulf coast. The larger the storm physically, the more it will push water from the gulf onto land. Additionally, Ian’s forward speed should slow significantly, which would also produce a higher storm surge.
The threat is NOT over for Tampa Bay or anywhere else from Southwest Florida to the Panhandle. Spread that word.
The National Hurricane Center’s forecast cone is a compromise between these unusually divergent tracks. This implies that the uncertainty of current forecasts is extremely high. Until this uncertainty is resolved, everyone should remain vigilant and pay attention to their local officials, who are responsible for keeping everyone safe.
NOAA and the National Weather Service are using every tool available to provide further clarity, and they will continue to do all they can over the next few days. Normally, their best technique is to collect additional atmospheric data around the storm and across the United States to ensure computer forecast models receive as much detailed information as possible. Often the additional data brings the different models closer together. But it hasn’t happened yet.
Even if the forecasts line up better, they will never be perfect. A Category 3 or 4 storm in the Gulf is an extremely dangerous scenario. Either way, it will be felt one way or another from the Keys to the Panhandle. It is essential that everyone stays informed. As we have seen, forecasts can suddenly change.
The other Atlantic systems are inconsequential, and nothing else appears in sight this week.