"Gustav is expected to be a large powerful hurricane as it approaches the northern Gulf coast"

.... Or so goes the last sentence in the current National Hurricane Center forecast discussion.

Right now, the level of complexity of Gustav's immediate future is higher than average for a hurricane. This is mainly because the two or three major atmospheric features that will determine Gustav's direction and rate of movement over then ext two days are themselves less predictable than ideal. This has been complicated by the fact that Gustav has grown very large laterally and very tall ... making it impossible for the hurricane observing aircraft to fly over the storm to see what is going on inside it.

Before getting too distracted by Gustav, please note that Tropical Storm is showing some potential and is not far behind. There are two tropical depressions coming off of West Africa as well, the first in line expected to blow out and the one currently closest to Africa looking like it has a high probability of developing into a tropical storm or hurricane.

Getting back to Gustav ...

The storm is increasing in size, both breadth and height, dramtically. The sterring currents are expected to shift the storm radically to the north but then back westward again. There is not much question as to whether or not Gustav will enter the Gulf of Mexico and strike land along the northern coast somewhere between Texas and the Florida Panhandle (inclusively). The two things that are most uncertain at this time are: How much wiggling back and forth (north south, mainly) is Gustav going to do over the next day or two, which will ultimately determine it's landfall perhaps more than later events; and how much strengthening will happen as the storm transforms to hurricane status over the next couple of days. Beyond that, there will be some uncertainty regarding strength as the storm does or does not pass over pockets of extremely warm Gulf water.

Here is the 5 day path currently provided by the National Hurricane Center:

However, keep in mind that the National Hurricane Center is explicitly stating, early morning on Friday, that they are 'sticking with' this prediction even though they know it is more uncertain than typically, as they await more critically important data later today. So assume less certainly for this model than normal, meaning, that the five day point is in an area of about 600 or more miles wide along the coast, and the expected strength is within a predicted range of perhaps 30 nautical miles either way.

On the other hand, my feeling is that whatever the predicted path for Saturday late morning or mid day will have much higher levels of confidence, as (it seems) many of the factors reducing certainty will have diminished in variability by then, and much better data will be available.

With respect to the political implications of a major hurricane looming over New Orleans as the Republican National Convention occurs in Saint Paul, things have changed a bit. The predicted path currently has the hurricane pulling up to the general vicinity of New Orleans, then slowing down a great deal (and quite possibly strengthening to a much stronger storm, or wearing down to a much smaller storm?), then grazing the lowlands of the coast for some distance before sliding on shore. So of all the possible things that could happen, we are looking at a situation of nearly maximal range of outcome, from a really really rainy week with manageable storm damage, to a killer storm causing more flooding than usual because it hangs around for a long time off shore.

The point is that all of this uncertainty will be happening in accordance with the schedule of the convention itself. It will be interesting to see how the news agencies balance this particular set of stories.