I want to start this post with a caveat: I’m not predicting that Ernesto will hit Miami. I just think the possibility is worth discussing, if we’re going to discuss worst-case scenarios. Certainly, there is no need for anyone in any particular location to panic. And, in terms of preparations, everyone within the forecast cone (which includes virtually all of Florida, and in the longer term, the entire East Coast up to the Delmarva), not just Miami and environs, should be getting ready for a possible strike. It’s also quite possible that Ernesto will so weaken over Cuba, it won’t be a major issue for anybody in the United States. All that said, however…

Earlier, I speculated about the possibility that Ernesto could be the nightmare hurricane for Key West and/or Tampa Bay. With the storm’s rapid weakening over Haiti, however, that seems less likely (though not impossible). But what about Miami?

At present, the official NHC forecast has Ernesto heading toward the west coast of Florida (specifically, the southwest coast). But the computer model tracks — and, consequently, the NHC forecasts — have been consistently trending further and further to the right over the last day or two:

It would only take a relatively small additional rightward deviation to bring Miami into the target zone:

That blue line is just a hypothetical “what if?” scenario, drawn by me and based on nothing scientific. That said, a couple of the computer models are predicting pretty much this very scenario (though I should point out that it is never a good idea to rely on a particular computer model for planning purposes).

As always, if the storm’s center comes in just to the left of the area of concern, in this case Miami, that would be the worst scenario in terms of both wind and storm surge.

Anyway… Margie Kieper recently cited the saying “the trend is your friend” — a financial motto which, in this context, reflects the lesson that when the computer models keep consistently shifting in a particular direction, looking at the forecast trend can be more helpful than looking at any one individual forecast. I’ve noticed this too, plenty of times over the years. In this case, it could potentially suggest that betting on a landfall east of the current “center line” in the NHC forecast track might be a good bet.

A Miami scenario wouldn’t just bring Ernesto toward one of America’s most vulnerable cities. It would also decrease the amount of time the center spends over land, and increase the amount of water available for it to restrengthen after exiting Cuba. In addition, the sea-surface temperatures between east-central Cuba and the Miami area are somewhat warmer than the SSTs between west-central Cuba and southwestern Florida, raising the possibility of greater strengthening:

Likewise the overall heat potential of the water:

On the other hand, such a track would also take Ernesto over higher terrain in Cuba, perhaps increasing the odds of the storm falling apart completely.

Also possibly going against my Miami theory is this line from the 11pm EDT discussion:

THERE COULD BE SOME SHIFTS WHEN THE 00Z MODELS COME OUT…AS THEY WILL HAVE THE BENEFIT OF DROPSONDE DATA FROM THE NOAA G-IV JET AND AN AIR FORCE C-130. A QUICK LOOK AT SOME OF THE 500 MB DATA SHOWS SOMEWHAT HIGHER HEIGHTS IN THE BAHAMAS THAN FORECAST BY THE GFS…SO I WOULDN’T BE TOO SURPRISED TO SEE THE 00Z MODELS SHIFT A LITTLE TO THE LEFT.

The 5:00 AM advisory will tell the tale. In the mean time, as long as the “trend” remains consistent, I’ll continue wondering about Miami.