The 11:00 AM EDT advisory is out. The headline is: “IKE GROWING IN SIZE AND STRENGTH IN THE SOUTHEASTERN GULF OF MEXICO.” Specifically, winds are up to 90 mph, and — more impressively — the hurricane-force wind field now extends 80 miles out from the center on the northeast side (and 60 miles on the northwest side; only 10 miles on the south side, though).
The good news: as of yet, no sign of rapid intensification. But that could change. The discussion states in part:
THE AIRCRAFT REPORTS INDICATE THAT THE SMALL INNER EYE IS ERODING AS OUTER BANDS SURROUNDING THIS FEATURE ARE BECOMING BETTER DEFINED. THIS COULD LIMIT RAPID DEVELOPMENT IN THE VERY NEAR TERM. HOWEVER…THE UPPER AIR PATTERN IS GOING TO BE VERY FAVORABLE FOR DEVELOPMENT OVER THE NEXT 24-48 HOURS…AND NOT MUCH LESS FAVORABLE THEREAFTER. IN ADDITION…THE FORECAST TRACK TAKES IKE OVER SOME WARM GULF EDDIES. WHILE THERE IS SOME DRY AIR IN THE WESTERN GULF…AND INDEED SOME OF THAT IS NEAR THE CORE RIGHT NOW…THE LARGE SIZE OF THE CIRCULATION AND OUTER BANDING SUGGESTS THAT IKE SHOULD BE FAIRLY EFFECTIVE IN FIGHTING OFF THESE NEGATIVE EFFECTS.
Here’s the new forecast track, essentially unchanged from the last one. It should be reiterated that, in the NHC’s words, “THE AVERAGE THREE DAY FORECAST ERROR IS NEARLY 200 MILES…AND . . . THE BEST ESTIMATE OF THE THREAT IS GIVEN BY THE NHC WIND SPEED PROBABILITY GRAPHICAL AND TEXT PRODUCTS.”
I’ll let others analyze this latest information in more detail — I’m sure the various bloggers linked at right, particularly the Houston Chronicle‘s Eric Berger, will have plenty to say this afternoon. (In addition, Berger will have a live chat at 3:00 PM EDT, which is well worth checking out.)
[UPDATE: Dr. Jeff Masters sums things up:
All indications are that Ike will intensify into a major hurricane that will bring widespread destruction to a large stretch of the Texas coast. I expect Ike will generate a 10-15 foot storm surge along a 100-mile stretch of Texas coast from the eye landfall location, northwards. I urge Texas residents to take this storm very seriously and heed any evacuation orders given. Most of you living along the coast have never experienced a major hurricane, and Ike is capable of causing high loss of life in storm surge-prone areas.
The point I’ve boldfaced is very important for Texas residents to understand. Just because you’ve survived some other, wimpier storm — or a storm that threatened a major-hurricane direct hit, but then weakened or turned aside — doesn’t mean you’ll survive Ike, if it hits you directly at major-hurricane strength. Again: if and when the local authorities tell you to leave, you should leave!]
[UPDATE #2: Ike is now a Category 2 hurricane, with 100 mph winds, as of 2pm EDT. He’s expected to reach Cat. 3 status “within the next 24 hours.”]
For my part, I want to pose four rhetorical, as-yet unanswerable questions, which I believe will be crucial to Ike’s future. As you read these, keep in mind: I’m not a meteorologist, I just play one on the Internet, so it’s possible I’m misstating some things here (and if someone knows better, please correct me in comments). But here, for what they’re worth, are my four questions:
1. Will the circulation ever “tighten up”? Currently, Ike has a minimum central pressure of 957 millibars — typical of a mid-range Category 3 — but its top winds are “only” 90 mph, a mere Category 1. This unusual (though certainly not unprecedented) situation is largely explained by the storm’s sprawling circulation: as I mentioned, hurricane force winds extend out 80 miles from the center. If Ike were to “tighten up” its circulation, we could see the winds get faster in a hurry, without the need for much “deepening” of the pressure. On the other hand, if Ike retains its current sprawling form, it may never become as intense as feared, but it could be just as damaging, if not moreso, due to the larger swath of strong winds and surge. That’s something the behemoth Katrina (which also, late in its life, had unusually low winds for its pressure) reminded us.
2. How soon will Ike strengthen? Everybody wants to know how strong Ike will get — Category 3? 4? 5? — but another very important question is how soon it will reach major hurricane status (if it does), and, relatedly, how long it will maintain that status. This is another lesson of Katrina: the severity of a storm surge isn’t just the product of the storm’s strength at landfall; it’s also related to the storm’s strength in the hours and days before landfall. So if, say, Ike makes it up to Category 3 tonight and Category 4 early tomorrow, and then weakens to a Cat. 2 shortly before landfall Friday night, it’ll still bring in a Cat. 3-4 strength surge to the highly vulnerable Texas coast. On the other hand, every hour that goes by without significant strengthening diminishes the potential for a catastrophic storm surge. All other things being equal, later strengthening is better than earlier strengthening.
3. Will small-scale disruptions persist? Alan Sullivan wrote this morning that “unpredicted shear from the west, and a plume of the drier mid-level air” were unexpectedly disrupting Ike. He later added that the “pulse of shear probably won’t weaken Ike; it will only retard strengthening for a time.” But sometimes, such small-scale, unpredictable, chaotic events — a pulse of shear here, a puff of dry air there — seem to happen one after another, preventing a potentially catastrophic hurricane from ever reaching its “potential.” Other times, they don’t. The NHC thinks Ike will fight off the dry air, and expects little shear, but the truth is, they don’t know for certain. The chaotic nature of these sort of events is one reason that predicting hurricane intensity is so difficult. (Another reason is eyewall replacement cycles, which sometimes — unpredictably — combine with these small-scale external disruptions to wreak unexpected havoc on a storm’s organization.) The best hope for Texas to avoid a serious blow from Ike, it seems to me, is probably a series of these small-scale disruptions over the next 24-48 hours, until Ike clears the warmest waters it will be passing over, and moves into an area where some moderate large-scale shear could begin to impact it.
4. When, and where, will Ike turn right? Dwight D. Eisenhower, a.k.a. “Ike,” is generally regarded as a moderate Republican, not a right-winger. But Hurricane Ike is expected to take a sharp “right turn” at some point near the Texas coast. The big, huge, million-dollar question is: will that turn occur just before landfall, or just after? The five-day forecast makes clear what a crucial question this is. The current landfall point is on Matagorda Island, just up the coast from Corpus Christi. Then, a few hours after landfall, Ike’s expected track bends abruptly to the right. Move that turn up by 6-12 hours — or, perhaps, slow Ike’s course down a bit — and we’d be talking about a Freeport or Galveston landfall instead. If the current large-scale forecast reasoning holds, it’s entirely possible we’ll spend the next three days singularly obsessing over the timing of this last-minute turn, with no clear resolution until it actually happens. If so, Ike’s landfall point may remain even more uncertain than usual, right down to the final hours, with excitable weather nerds like me going nuts over every “wobble” on radar. It could make for a very interesting, and nerve-wracking, Friday night and/or Saturday morning.
P.S. Point #4, in particular, makes the job of disaster planners and local officials in the Houston/Galveston area incredibly difficult. Do you trust the forecast track, and the computer models, so long as they continue to insist that the northward turn will happen over land, after landfall? Or do you order evacuations, out of an abundance of caution, even though the storm will probably hit the Corpus Christi area, well to Galveston’s southwest? If you choose Option A, you have to pray the right turn doesn’t happen early. If you choose Option B, you risk freaking out the populace with another false alarm, leading to cynicism and complacency down the road. “It’s Rita all over again,” many would say, even though that isn’t remotely fair. Nevertheless, it seems to me that Option B is the only viable choice in the scenario I’m envisioning. But I don’t envy the folks who have to make that call.
UPDATE, 4:30 PM: In comments, Leland writes:
I don’t think the question should be “when will Ike turn right?” but rather, “when will Ike turn left?” The 2pm EDT model runs still show a [slight] turn left before making the big right hook; however, the storm is now moving further north than it was the last 2 run cycles.
Leland makes a good point. If you look at the visible satellite loop, and click the check-box that says “Trop Fcst Pts,” you’ll see that Ike’s center currently appears to be ever-so-slightly north of the predicted forecast track. This is probably just another temporary wobble, but if I were living in the Houston/Galveston area, it would make me a wee bit nervous… to say nothing of the new GFDL model forecast…
Of course, there’s always the “Rita scenario,” mentioned by Eric Berger in his just-concluded live chat:
The three-day forecast for Rita was centered about where Ike was forecast to go this morning, and then the models started moving north…
Who knows, maybe Ike will end up going north of Houston, like Rita did. I wouldn’t bet on it, but at this point, lots of scenarios are still possible. That’s why they call it the “cone of uncertainty,” folks. (And/but: the UKMET and ECMWF, which have done better with Ike so far than the GFDL has, are not yet following the GFDL north. And remember, the models have been bouncing around a lot — they might shift back south at 8pm. Who knows what will happen? Nobody, that’s who.)
Anyway, there will be a new advisory — complete with a new discussion, a new forecast track, and a new “cone” — at 5:00 PM EDT. Go to the National Hurricane Center website for that.
NOTE: This update was originally its own post, but then I decided it didn’t merit that treatment, and moved it to the bottom of this post.
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