5-Day Forecasts on Hurricane Bill

I remember well the outcry from many people when the National Hurricane Center (NHC) was planning to go from a three-day to a five-day forecast on tropical cyclones.  The NHC tested the five-day forecasts in-house during 2001 and 2002, shared those results with stakeholders, and went operational in 2003.

I would hope that most folks would agree that in the case of Hurricane Bill, the five-day forecast along with confidence in the more sophisticated computer models has helped relieve a considerable amount of stress to millions of people living in the southeastern United States.

Current 5-day cone forecast on Hurricane Bill issued at 5:00 pm Aug 18, 2009 from NHC

Current 5-day cone forecast on Hurricane Bill issued at 5:00 pm Aug 18, 2009 from NHC

Since Sunday, the NHC has consistently indicated that Bill would turn toward the north well before approaching the southeastern U.S.  Hurricane Bill has not even reached its closest point of approach to the Leeward Islands, yet the long range forecasts for the past few days have not even hinted at possible direct impacts to the southeastern U.S.  Not too many years ago, there would have been a lot of concern in the southeastern U.S. with a powerful hurricane in the deep tropics still headed west-northwestward.  At least in this case, I think the 5-day forecast has been a big help.  Much credit goes to the hard working scientists in numerical modeling centers around the world for, at least in this case, providing consistent and reliable guidance out to five days on Bill.  Of course, Bill will still be around for several more days and the final impacts are not yet known.

There is still uncertainty in how close Hurricane Bill will get to the northeast coast of the U.S. although most models currently have the core of the hurricane remaining offshore the U.S.  But Bill is a large and powerful hurricane, and there will surely be significant long period swells that will impact portions of the U.S. east coast late this week and into the weekend.  And residents and visitors on Bermuda obviously need to keep up to date with the latest on Bill.

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3 thoughts on “5-Day Forecasts on Hurricane Bill

  1. Hi again Max. Very interesting article. Thank you. Yes, you e-mailed me late last week saying the models were turning what has turned out to be Bill to the north, away from So. Florida, thank heavens.

    I’m curious: what are the models saying about the blob that’s coming off the coast of Africa now? The guy at hurricanetrack.com (Mark Sudduth) is saying this: “There is yet another very well organized tropical wave justt of the African coastline. This should develop steadily as it moves westward at around 10-11 degrees latitude. For what it’s worth- the ECMWF model, which called Bill’s turn to the north very early on, shows this next feature coming much farther west in about a week.” It he accurate?

    Thanks again Max. Take care.

    Amy

  2. “Much credit goes to the hard working scientists in numerical modeling centers around the world for…”

    Because some things cannot be said often enough…

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