Wednesday, September 08, 2004
The trouble with Hurricane Ivan
Josh Larson @ 5:15 PM
It is disconcerting to realize that the computer model guidance for, arguably, one of the most dangerous hurricanes of the season so far is wildly varied and contradictory. If anything, models have diverged even further over the past 24 hours.
The most recent Air Force reconnaissance reveals that Hurricane Ivan is holding together quite well, with excellent outflow and a tight eye. It has maximum sustained winds of near 145mph and is moving to the west-northwest at about 17 miles per hour; it is now about 640 miles east-southeast of Kingston, Jamaica.
And while the official TPC track forecast is reasonable, it is only an average of some very different possible scenarios - certainly not ideal for forecasting. There has been poor run-to-run model consistency, and the most recent run of the GFS should all but be ignored (as it curves Ivan away from the continental US, probably in response to an erroneous estimation of the strength of the Bermuda high). Most of the remaining models keep Ivan on a much more westerly track, south of Florida, into the Gulf of Mexico. However, there is considerable divergence within the most recent runs of the CMC, GFDL, UKMET, and NOGAPS as to how far south of Florida Ivan is likely to trek, and whether, once in the Gulf of Mexico it continues west or north-westward, or whether it turns to the right, setting its sights, like Charley and Frances, on ravaged Florida.
Unfortunately, we are essentially in a wait and see scenario at the moment, not much comfort to those in the Southeast US, but there simply are not enough strong, unambiguous atmospheric signals to suggest how Ivan will behave as it treks closer to the US and encounters very weak steering currents aloft.
The most recent TPC discussion highlights this important point:
IT MUST BE RE-EMPHASIZED THAT THE FORECAST TRACK BEYOND 72HOURS CONTINUES TO BE HIGHLY UNCERTAIN SINCE STEERING CURRENTS ARE FORECAST TO BE WEAK AND NOT WELL-DEFINED IN THE FORECAST MODELS. THE SPREAD IN THE MODELS CONTINUES IN THE LATEST 12Z RUN.
You will see below an image of possible routes Ivan may take over the next week, and hopefully in the next few days we should have a much better idea what may happen. At the moment, I am favoring track #3, followed by track #2. I believe that track #1 is highly unlikely, with track #4 possible but less likely than #2 or #3.
Stay tuned for more updates....
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