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Hurricane Ivan - Tuesday - September 7, 2004 - 9:30 PM


CURRENTLY: Ivan reaches Cat 4 intensity….max sustained winds based on recon of 135 mph. Latest satellite depicts another mighty hurricane in the Atlantic basin. Ivan has a tight compact eye, a symmetrical CDO, good to excellent outflow in all quadrants and an overall near perfect satellite presentation. It is most unusual to have a hurricane of this magnitude this far south in the Atlantic basin….also most unusual is to have a hurricane of this magnitude to be moving along so briskly.

Ivan is currently moving west (275-280 degrees) at 18 mph. While this 18 mph is somewhat slower than the 24 mph it had been doing it is still rather fast.

INTENSITY: I am surprised by the intensity of Ivan, I was expecting a hurricane more or less in a steady state for the last 24 hours...but even with the fast forward motion and low latitude Ivan has managed to ramp up to 135 mph.

I still believe we will see a falling off of intensity over the next 24-36 hours or so as some southerly shear increases over Ivan and also I think of more importance it passes rather close to the northern coast of South America and entrains some "drier" continental air. We'll see what happens….even if I'm wrong about this…there will be some eye wall replacement/concentric eye wall cycles that will cause some intensity fluctuations over the next 24-60 hours.

LONGER TERM INTENSITY: No change in thinking here from my last post Monday evening. Once beyond 60 hours or so as Ivan clears the northern coast of South America and bends more w.n.w. into the open western Caribbean the possibility exists for some significant intensification. Upper winds are forecast to be favorable and Ivan will be moving over water with a high oceanic heat content.

If Ivan is to reach Cat 5 status it will be in the longer ranges over the western Caribbean or southern Gulf of Mexico. This assumes my track thinking below is correct and Ivan stays clear of the effects of the Greater Antilles…which I feel he will.

Let me be clear….while intensity forecasting in the short range is tricky it has even less skill beyond 60-72 hours….however, given the data I'm seeing I must at least say the potential exists for a very intense hurricane in 4-5 days over the western/northwestern Caribbean or southern Gulf of Mexico. I'd say the upside POTENTIAL is about 160 mph if everything falls into place. Also, Ivan also looks like it will become a large hurricane with a wide sweeping wind field…much like Frances.

Track: No changes to thinking expressed in Monday post.

Ivan entered the Caribbean south of Barbados today, passing right over Grenada. Damage reports out of there should be interesting.

Ivan continues to move slightly north of due west 275-280 degrees…a gradual turn more west-northwest is expected once past 70W.

I am currently forecasting Ivan to pass over or more likely SOUTH of Jamaica, Friday morning or afternoon. Once past Jamaica expect a path into or toward the Yucatan Channel…then into the Gulf.

Once into the southern Gulf it will be a matter of timing and placement of a trof pressing east from the western U.S. and how strong the western edge of the sub-tropical ridge is.

Right now I would suggest residents from the TX/LA border east to the west coast of Florida (it pains me to say that) pay close attention to future updates on Ivan.

My track is just a shade to the left (splitting hairs really) of the 5 P.M. official track and for all practical purposes I'm essentially in total agreement with the latest 5:00 P.M. TPC package.

There is quite a bit of model spread as well as flip-flop….but the model consensus is pretty much on top of TPC track and really can't argue.

The potential exists for a strong and dangerous hurricane to be in the southern Gulf of Mexico this weekend.

Stay tuned……….


Please refer to official statements from TPC and local weather services offices for official information. Please obey all evacuation orders as issued by local emergency service offices.