If the steering flow weakens and/or changes -- such as the trough currently sending Ivan to the NE lifts out, leaving the storm behind to slow down and a ridge to build in from the north to shunt it towards the west -- you can see that sort of pattern evolve.

Interesting to note that a few of the models want to interact the remnants of Ivan with Jeanne in 4-6 days. We'll see if that happens, sort of merging together or whatnot.

I think I'm going to take a break from the prediction business for awhile...these storms this year have proven one thing -- they're really, really tough to predict. Just one look at how Jeanne has fared over Puerto Rico and Hispaniola confirms that -- stronger storms have been ripped apart by those two islands.

TUTT is the acronym for tropical upper-tropospheric trough. In general, it stretches across the western tropical/subtropical Atlantic with a few upper-level low centers (TUTT cells) along its path. This map -- http://www.nrlmry.navy.mil/~chu/chap2img/fig215.jpg -- shows you the climatological position of the TUTT in July over the N. Atlantic to be somewhere south of Bermuda. The TUTT is a semi-permanent feature that tends to both enhance and deflate tropical activity, depending on its strength and location as well as other external influences on tropical cyclone development.

More information on the TUTT and upper-level troughs in the tropics in general can be found here: http://www.nrlmry.navy.mil/~chu/chap2/se205.htm