Weather Nerd

Gustav stalls over Haiti; where to now?

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At 5:00 AM EDT, the National Hurricane Center stated that Tropical Storm Gustav had stalled over Haiti. The storm’s stall prompted weatherblogger Alan Sullivan to write:

In my last post … I wrote of an upper low that was impinging from the NE. Overnight that system continued to press against the landmasses of Puerto Rico and Hispaniola, while the tropical storm remained caught on the jaw of Haiti, losing strength, though maintaining strong convection over waters just offshore to the south. Now what? Gustav will surely lurch free of the land sometime later today, but which way will it go? WSW — away from the repellant force of the upper low pressing at its flank? That would put the system on track for major intensification south of Cuba, and serious threat to the Gulf Coast of the US. Or WNW — crossing the short stretch of water toward Cuba and promptly making another landfall? Such a course would keep Gustav weak, and we would be looking at another Fay rather than a potential Katrina. It will be an interesting day for satellite interpreters.

Here are the visible, infrared and water vapor satellite loops.

As of 8:00 AM EDT, the NHC says Gustav is moving again, to the northwest at 5 mph. Not sure how much to make of that, though. They still say a WNW and then due-west turn is expected.

The computer models, as of 2:00 AM, were still almost unanimous in predicting that Gustav would remain south of Cuba. Only the AVN calls for an overland track, and the NHC is, at least for now, dismissing this as an “extreme outlier.” We shall see. Meanwhile, the GFDL has shifted back from a Houston/Galveston landfall to a New Orleans landfall. But again, it’s way too early to know that level of detail.

The Houston Chronicle’s Eric Berger writes:

The official forecast brings Gustav toward the central Louisiana coast by early Monday morning. … [Computer model] guidance suggest[s] a landfall anywhere from Texas’ Coastal Bend to the Florida Panhandle. At this time, however, Louisiana remains the likeliest target. …

Some models, notably the GFDL, bring Gustav into the Louisiana coast as early as Sunday night. Meteorologically this seems a bit too quick, and a landfall sometime Monday or Tuesday along the Gulf coast seems much more likely.

About Gustav’s current stall or near-stall, Berger writes: “If the storm continues to stall it could favor a Texas landfall as the time should allow a ridge of high pressure over Florida and the Bahamas to strengthen and possibly expand. It is around this ridge that Gustav will eventually trace its way into the Gulf of Mexico, so the further west the ridge moves, the further west Gustav will move.”