Could we have a hurricane spinning and strengthening in the Gulf of Mexico, menacing the coast, on the one-year anniversary of Hurricane Katrina? It looks increasingly likely. Here’s the latest five-day forecast track from the National Hurricane Center:

It’s way too early to start seriously speculating about possible landfall locations… but, do you think the folks affected by Katrina and Rita are feeling a little nervous right now? Yeah, I think so too. (That said, everyone from Florida to Texas should be watching this thing closely. Five-day forecasts have a very wide margin for error, as the track “cone” indicates.)

The official forecast has Ernesto reaching hurricane strength on Monday, sitting on the borderline of Category 1 and 2 on Tuesday (the anniversary of Katrina’s landfall), and achieving Category 2 strength on Wednesday. And, as is the NHC’s wont when it comes to long-range intensity forecasts, those predictions are conservative: “MOST OF THE INTENSITY GUIDANCE INDICATES AN EVEN STRONGER INTENSITY.” It’s easy to see why. If the forecast scenario plays out as advertised, I don’t see what would stop Ernesto from become an intense hurricane:

CURRENTLY AN UPPER-LEVEL LOW IS SITUATED OVER EASTERN CUBA AND JAMAICA WITH STRONG WEST-SOUTHWESTERLY WINDS TO ITS SOUTHEAST. WATER VAPOR IMAGERY INDICATES THIS UPPER-LEVEL LOW IS MOVING RAPIDLY TO THE WEST-SOUTHWEST…AND THE MODELS ARE IN CLOSE AGREEMENT THAT THE LOW SHOULD END UP ALONG THE EASTERN COAST OF MAINLAND MEXICO IN 3 TO 4 DAYS. THIS SCENARIO SHOULD PROVIDE A VERY WEAK SHEAR ENVIRONMENT FOR ERNESTO TO STRENGTHEN…AND IN FACT THE SHIPS GUIDANCE FORECASTS THE SHEAR TO WEAKEN CONSIDERABLY IN 36-48 HOURS AND REMAIN WEAK THROUGH DAY 5.

The Houston Chronicle’s SciGuy says Ernesto could still fall apart before becoming a major threat, a la Chris:

The next 24 to 36 hours are critical because there’s still a good chance wind shear can tear the storm apart by Sunday. But if it continues to strengthen and remains intact by Sunday night, the system will be a threat to all points along the Gulf.

Potentially, a very serious threat. A well-developed tropical cyclone + minimal wind shear + the Loop Current = trouble. Yikes. Stay tuned.

P.S. Charles Fenwick is emphasizing the track forecast error margin:

The models are in excellent agreement for the first two days of the forecast, but diverge significantly after that. One shouldn’t put much weight in the track forecast after that, Because it’s just a hedge of the different model outputs, it doesn’t favor any of them. 5 day forecasts always have a large amount of uncertainty in them, but it’s even moreso in this instance. Everyone on the Gulf coast should keep a bit of an eye on Ernesto this weekend to see how the forecast evolves and be thinking about what preparations they may need to make during the early part of next week.

Dr. Jeff Masters has more.

P.P.S. Quoth Margie Kieper:

Just sit tight and make a plan, and try to chill for the weekend, and do not look at the CONU 26/0000Z. There’s no way to know until Sunday evening exactly how this is going to shake out, and what we’ll be expecting on Tuesday, but it will likely be something a little more complex than an anniversary.

P.P.P.S. The Storm Track has much more, including this map and description of the warm waters that lie ahead:

By using radar altimeters aboard satellites, we can actually see an expansion of the ocean and higher sea levels where there are deep layers of warm water. One such deep layer is positioned just south of Louisiana at this time. Oceanographers call these features “warm core rings” and they are nothing more than warm parcels of water that break off of the Loop Current near the Florida Keys and drift northward towards Louisiana and eventually westward towards Texas. This particular warm core ring is extremely strong and would provide an incredible amount of energy to any hurricane that would pass over it. Warm core rings weaker than this one were responsible of the very rapid strengthening observed in hurricanes Opal, Katrina, and Rita among others. If Ernesto were to drift over this warm tongue of water with favorable atmospheric conditions, as are currently being forecast at that time, Ernesto could undergo a very rapid strengthening. It is worth noting that a similar feature is noticeable to the south of Cuba in the previous map.

As I said: Yikes.

UPDATE, 4:37 AM: In the 2:00 AM EDT public advisory, the NHC says, “…AIR FORCE PLANE FINDS A BETTER ORGANIZED ERNESTO…” The wind speed remains the same for now (45 mph), but the pressure has dropped from 1003 mb to 999 mb. Hopefully the 5:00 AM advisory will clarify matters.

UPDATE, 4:50 AM: The 5:00 AM discussion says:

AN AIR FORCE PLANE HAS BEEN INVESTIGATING ERNESTO AND FOUND THAT THE CENTRAL PRESSURE DROPPED TO 999 MB WITH A WELL-ESTABLISHED CYCLONIC CIRCULATION. HOWEVER FLIGHT LEVEL WINDS HAVE NOT INCREASED MUCH SINCE THE PREVIOUS FLIGHT.

So, “better organized,” but not stronger… yet.

The intensity forecast has been nudged again toward faster and greater strengthening. Ernesto is now expected to be a hurricane by Sunday night, a Category 2 by Tuesday night, and a Category 3 by Wednesday night. That’s right, the NHC is now officially predicting that Ernesto will become a major hurricane. The discussion explains:

ERNESTO HAS BEEN A FIGHTER AND HAS BEEN ABLE TO SURVIVE THE STRONG SHEAR SO FAR. UNANIMOUSLY…ALL GLOBAL MODELS DEVELOP AN UPPER-LEVEL RIDGE OVER ERNESTO…A PATTERN WHICH IS CONDUCIVE FOR STRENGTHENING. THIS UPPER-LEVEL PATTERN COMBINED WITH THE VERY WARM WATERS AHEAD OF THE CYCLONE COULD LEAD TO SIGNIFICANT STRENGTHENING OVER THE NEXT FEW DAYS. THIS COULD RESULT IN ERNESTO BECOMING A POWERFUL HURRICANE IN THE GULF OF MEXICO. THE INTENSITY FORECAST IS LOWER THAN THE GFDL AND VERY SIMILAR TO SHIPS AND FSU SUPERENSEMBLE. OF COURSE…THE INTENSITY FORECAST IS HIGHLY UNCERTAIN AND STRENGTHENING MAY NOT OCCUR AT ALL IF THE SHEAR DOES NOT DECREASE.

Things could change, but my gut tells me this is the real deal. The NHC seems to feel the same way, judging from the ominous closing like of the discussion:

IN SUMMARY…ERNESTO COULD BECOME A POTENTIALLY DANGEROUS HURRICANE AS IT MOVES ACROSS THE NORTHWESTERN CARIBBEAN SEA AND THE GULF OF MEXICO. INTERESTS IN THESE AREAS SHOULD CLOSELY MONITOR THE PROGRESS OF THIS SYSTEM.