1. Climatology …The track which systems that developed in roughly the same area as Ivan have taken over the past 50 years, and reached hurricane status during their active period.
2. Persistence…or the track the majority of systems which developed This year have taken
3. The current data.
Since 1954 there have been 21 systems which have formed in the same area as Ivan---in a box bounded by 5N-15N/25W-35W. There is a wide range and diverse set of tracks which these systems took however they can be organized into three specific groups.
Group one: systems which harmlessly remained out to sea w/ little effect on land.
Fabian in 2003 was a chance-impact on Bermuda. However affected no other landmasses
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Luis, 1995 affected the NW islands however did NOT enter the Caribbean.
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11/21 (53%) took this track and for the most part avoided land. The only land impacts were Fabian last year (2003) and Luis in 1995.
Group two: Systems which affected the east coast of the United States
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Hurricane Dennis did enter the Caribbean, struck Cuba, Florida and moved up along the SE coast as a TS. It did not attain Hurricane status until after passing ENE off the NC coast.
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In total there were 4/21 (19%) of the storms assessed that fit into this category.
Furthermore, all of the systems that fit into this category also made landfall along the East coast.
Group three: systems which remained at fairly low latitudes—then entered the Caribbean and/or GOM.
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Hurricane Flora entered the Caribbean and impacted Hispaniola, Cuba, and the SE Bahamas before turning NE out to sea
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6/21 (29%) fit into this category.
It would seem that a track out to sea and away from land (the “fish” track) is most common for systems which form in an area bounded by 5N-15N/25W-35W (53% took this track), w/ gulf/Caribbean track coming in second (29% of total) and those taking a track which would bring them into contact w/ the EC east coast being the least common (only 19%)
ONLY ONE of the 21 systems above impacted Florida. That was Hurricane Dennis in 1981, as a tropical storm.
Ok, now let’s see what we can infer from the tracks of other systems this year—or the PERSISTENT track in order to determine what Ivan may do.
As you can see, the hands down most persistent track this season is one that has taken systems into contact with the east coast—pretty much regardless of origination point and then northeast parallel to the continent. The clear outlier was Danielle. It was also the only system to avoid any interaction with land this year, even TD two (later re-evolved into Bonnie) and TS EARL impacted southern Islands.
The systems this year that formed at low latitudes (e.g., Charley, Frances) near or just North of 10 N and excluding Earl have hit the US mainland; this of course would not be a positive for those in FL or anywhere along the SE and Gulf coast.
In regard to Ivan, the persistent track for most other systems this season would seem to suggest that Ivan is at the VERY least a threat to the US mainland and, yes Florida (unfortunately) as well as the islands in the Caribbean. It is also unsettling to note that our two low latitude systems--forming east of 35W this year (Frances and charley) have hit Florida. Crisscrossing each others paths
Based on most of the data over the past few days, the out-to-sea option regarding Ivan’s potential is most likely off the table.
18z 9/6 Tropical models
The data unanimously indicates that Ivan is a potential threat over the next few days to anyone from the SE Bahamas to the Yucatan (which the new UKMET seems to favor)
12z ECMWF:
By 120hrs the ECMWF has IVAN located near Hispaniola/Cuba moving WNW underneath the ridge.
Compare that to the previous location on the 0z Run at the same time which was MUCH…MUCH further east
The 12z ECMWF does not negate the threat to Florida, and would have implications for the southern and western half of the state as the ridge weakens somewhat and slides off to the east and the trough progressing eastward over the US at 168 hrs affects its track somewhat.
The 12z Canadian global model however, seems to support the UKMET w/ Yucatan threat w/ the ridge pretty much remaining intact – forcing a more westerly track also. The 0z GGEM run was similar to the 12z ECMWF.
0z 9/6 GGEM at 144 hrs VT 0z SUN 9/12:
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There appears to be enough of a weakness in the ridge to allow more of a NW motion after emerging from the FL strait that could once again put the Gulf side of FL at risk.
By 168 hrs (according to the 0z GGEM) the trough catches Ivan and drives it into the eastern Panhandle—around the big bend and eventually phases it with the mid latitude system---thereafter creating a large/strong extra tropical low over the Appalachians at 192 hrs. ALSO this would mean ALOT of heavy rain for the Eastern US once again, and the potential for a significant severe weather threat east of the mountains IF it were to verify.
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I believe that Ivan is a major threat to the islands of the Caribbean, as well as the US mainland. While the trend in the data today is SOMEWHAT more promising for those in Florida WRT the westerly trend in the data, and worse for those along the Gulf coast--no one should let their guard down across the state of FL, until it can be determined that Ivan is NOT a potential threat.
I do think that the threat of the east coast north of FL/GA boarder has diminished even more given this turn of events. The trough over western North America should continue to pump the downstream ridge and force Ivan on a more Westerly or WNW track at least into the weekend.
How much of an influence the weakness left behind in the wake of Frances has on the track of Ivan (if any) remains to be seen also.
