[Rhodes22-list] IKE - Heads-Up Call

[Jim White]

Battening the hatches again. Right now the projected path is pretty far north (as always depending ona couple of factors).....
jw

--- On Tue, 9/9/08, Brad Haslett <flybrad at gmail.com> wrote:

From: Brad Haslett <flybrad at gmail.com>
Subject: [Rhodes22-list] IKE - Heads-Up Call
To: "The Rhodes 22 Email List" <rhodes22-list at rhodes22.org>
Date: Tuesday, September 9, 2008, 9:39 PM

Info for Texas coastal Rhodies - Brad

----------------

 September 9th, 2008 6:07 pm
Ike reaches the Gulf; could be a "worst-case" storm for Texas


Hurricane Ike has emerged in the Gulf of Mexico, having survived its
long passage over Cuba relatively intact, and it has a good chance of
intensifying into a major hurricane — and aiming for a highly
vulnerable part of the Texas coast. According to Dr. Jeff Masters,
"There is a significant chance that Ike will be the worst hurricane to
hit Texas in over 40 years."

The standard caveats apply. Landfall in Texas is more than three days
away. We don't know — we can't know — exactly where Ike will go,
how
strong it will get, or whether it will maintain its strength all the
way to the coast. There are plenty of plausible scenarios which are
not "worst case." The odds do not favor a calamity. They never do, at
72+ hours out. But Ike is a real threat.

This new sense of worry is fueled partly by the track. As I mentioned
earlier, the trend toward a landfall in more sparsely populated south
Texas or northern Mexico has halted, and now the computer model tracks
are inching north — and getting uncomfortably close to the heavily
populated, highly vulnerable Houston/Galveston region. In Eric
Berger's words, "if the models were to shift just 50 or so miles up
the coast, a landfall at Freeport or just to the northeast would bring
the strongest winds to Houston."

The new official forecast track brings Ike ashore just north of Corpus
Christi, and the National Hurricane Center's 5:00 PM discussion
acknowledges that this may be too far south:

    THERE HAS BEEN A SIGNIFICANT NARROWING IN THE SPREAD OF THE LATEST
MODEL RUNS…WITH THE GFS…GFDL…AND NOGAPS ALL SHOWING LESS RIDGING TO
THE NORTH OF IKE LATE IN THE PERIOD AND SHIFTING THEIR TRACKS
NORTHWARD TO BE IN BETTER AGREEMENT WITH THE UKMET AND ECMWF RUNS. IKE
IS NOW EXPECTED TO RECURVE AROUND THE PERIPHERY OF THE SUBTROPICAL
RIDGE NEAR THE END OF THE FORECAST PERIOD. THE OFFICIAL FORECAST IS
ADJUSTED NORTHWARD ON DAYS FOUR AND FIVE…BUT ALL OF THE BETTER
DYNAMICAL MODELS ARE EVEN FARTHER TO THE RIGHT.

Translation: if the models don't lurch back to the left, the NHC's
forecast landfall point will move further away from Corpus Christi and
closer to Freeport — the west edge of Houston/Galveston's
"worst-case"
landfall zone.

The other reason for alarm is Ike's failure to fall apart during its
on-again, off-again overland trek across Cuba, which has just ended.
It took Ike almost 48 hours to traverse the island from end to end,
and the storm's winds diminished from 135 mph a few hours before
landfall, and 125 mph at landfall, to 75 mph now. But the storm's core
remains structurally well put-together, which is the key to future
strengthening.

This is a crucial difference between Gustav and Ike. Although Gustav's
passage over Cuba was quite brief — just a few hours — the effects of
land interaction, combined with wind shear, were enough to
significantly disrupt the storm's central core, delaying rapid
intensification until it was too late for Gustav to re-intensify into
a monster. By contrast, Ike's much lengthier passage of Cuba did not
have the same effect. According to the National Hurricane Center's
5:00 PM discussion:

    IKE MAINTAINED A FAIRLY WELL ORGANIZED CORE STRUCTURE DURING ITS
PASSAGE OVER WESTERN CUBA . . . IT APPEARS THAT THE CORE IS INTACT
ENOUGH TO TAKE ADVANTAGE OF SOME VERY FAVORABLE CONDITIONS IN THE GULF
OF MEXICO.

Dr. Masters summarizes things even more bluntly:

    All indications are that Ike will intensify into a very dangerous
major hurricane . . . [S]atellite loops show that Ike has maintained a
large, well-organized circulation during its passage of Cuba. The 4 pm
EDT center fix from the Hurricane Hunters found a central pressure of
968 mb, which is characteristic of a Category 2 hurricane. Passage
over Cuba did not disrupt the storm enough to keep Ike from
intensifying into a major hurricane over the Gulf of Mexico.

The barometric pressure issue is particularly interesting. Ike's
pressure just before landfall in Cuba was 945 mb, typical of a
borderline Category 3/4 hurricane, which is exactly what Ike was at
the time. During the passage of Cuba, the pressure rose "only" to 968
mb, its current value, which is typical of a borderline Category 2/3
hurricane — not the borderline tropical storm/Cat. 1 that Ike actually
is. One reason for this, as I understand it, is that Ike has responded
to land interaction by spreading out its wind field over a wider area,
which (I believe) tends to cause a hurricane to be "weaker,"
wind-speed-wise, than its central pressure would normally indicate.

If I'm not mistaken — and here I must add the caveat that I'm not a
meteorologist, I just play one on the Internet, so someone please
correct me if I'm wrong — it would not be surprising to see Ike
"tighten up" a bit over the Gulf, allowing its winds to ramp up to
something more typically in line with the low barometric pressure. In
other words, Ike might not actually have to "deepen" all that much to
become a Category 2 or 3 hurricane.

In any case, assuming Ike does become a major hurricane over the Gulf
— which seems likely, given its core's organization, and given that
both the Loop Current and a Loop Current Eddy stand between it and
Texas — the big question is whether, and how much, it will then weaken
before making landfall.

Alan Sullivan (who, like me, is an amateur weather buff, not a
meteorologist) foresees substantial weakening:

    [Ike's track will take it] into a zone of shear, cooler water, and
interaction with an approaching cold front. Such a scenario could
yield very heavy rains, but it would not be likely to put a major
hurricane ashore. Ike would weaken.

But Dr. Masters, who is a meteorologist (indeed, the co-founder of
Weather Underground), is less confident of such an eventuality:

    The wind shear for Friday has changed, and we are expecting wind
shear to remain around 15 knots, which is still low enough to allow
intensification. There is much higher oceanic heat content off the
Texas coast than was present off the Louisiana coast for Gustav. Thus,
it is more likely that Ike will be able to maintain major hurricane
status as it approaches the coast. . . . Given the impressive
appearance of Ike on satellite imagery, and the forecasts of high heat
content and low shear along its path, I would be surprised if Ike hit
as anything weaker than a Category 2 hurricane with 100 mph winds.
Here's my rough probability break-down for Ike's strength at landfall,
I forecast a 50% chance Ike will be a major hurricane at landfall:

    Category 1 or weaker: 20%
    Category 2: 30%
    Category 3: 30%
    Category 4 or 5: 20%

A major-hurricane landfall anywhere along the middle Texas coast would
be a very bad thing, as Dr. Masters points out with his explanation of
why "Texas is highly vulnerable to storm surge." But nowhere is the
threat greater than in  Houston/Galveston, as this 2005 article by
Berger explains in detail:

    Houston's perfect storm would feed on late summer's warm waters as
it barreled northward across the Gulf of Mexico, slamming into the
coast near Freeport.

    A landfall here would allow its powerful upper-right quadrant,
where the waves move in the same direction as the storm, to overflow
Galveston Bay. Within an hour or two, a storm surge, topping out at 20
feet or more, would flood the homes of 600,000 people in Harris
County. The surge also would block the natural drainage of flooded
inland bayous and streams for a day or more.

    Coastal residents who ignored warnings to flee would have no hope
of escape as waters swelled and winds roiled around their homes. Very
likely, hundreds, perhaps even thousands, would die.

    Meanwhile, as the storm moved over western Harris County, its most
dangerous winds, well in excess of 120 mph even inland, would lash the
Interstate 45 corridor, including Clear Lake, the Texas Medical Center
and downtown.

    Many older buildings could not withstand such winds.

    Anything not tied down, from trees to mobile homes to light poles,
would become missiles, surreally tumbling and flying through the air,
flattening small houses, shattering skyscraper windows and puncturing
roofs.

    "Unfortunately, we're looking at massive devastation," said
Roy
Dodson, president of the engineering firm Dodson & Associates, which
Harris County asked to model realistic "worst-case scenarios" for a
major hurricane hitting the area.

    Dodson's firm modeled more than 100 storms of varying power, speed
and landfall. It concluded that a large Category 4 or Category 5 . . .
would cause as much as $40 billion to $50 billion in damage.

Now, before anyone accuses me of "hype," please re-read the second
paragraph of this post. The odds do not favor a calamity. But a
worst-case scenario, or something close to it, is now a realistic
possibility, albeit one that's far from certain. Texas residents need
to watch this storm very closely, and not be lulled into a false sense
of security by previous false alarms (Rita, Edouard, etc.). Ike could
be the real deal. Maybe it won't be — but it could be.

Berger, circa 2008, says of Ike: "The bottom line is that the Houston
area could face a near worst-case scenario with Ike, although I'd
still peg the chances of this happening at one-in-four, or less." He
is, I believe, including any major hurricane landfall (Cat. 3 or
above, not just Cat. 4 or 5) hitting between Freeport and Galeveston
in his "near worst-case" category.

Dr. Masters, for his part, spells out "a realistic worse-case scenario
for Texas":

    There is a significant chance that Ike will be the worst hurricane
to hit Texas in over 40 years. The latest run of the HWRF and GFDL
models paint a realistic worst-case scenario for Texas. These models
bring Ike to the coast as a Category 4 hurricane (which I give a 20%
probability of happening). The HWRF predicts a 170-mile stretch of
coast will receive hurricane force winds of 74 mph or greater. A
100-mile stretch of coast will receive winds of Category 3 strength
and higher, 115 mph. Hurricane force winds will push inland up to 50
miles, along a 50-mile wide region where the eyewall makes landfall. A
100-mile stretch of Texas coast will receive a storm surge of 10-15
feet, with bays just to the right of where the eye makes landfall
receiving a 20-25 foot storm surge. This is what Hurricane Carla of
1961 did to Texas. Carla was a Category 4 hurricane with 145 mph winds
at landfall, and drove a 10 foot or higher storm surge to a 180-mile
stretch of Texas coast. A maximum storm surge of 22 feet was recorded
at Port Lavaca, Texas. Despite the fact that the center of Carla hit
over 120 miles southwest of Houston, the hurricane drove a 15-foot
storm surge into the bays along the south side of the city.

Bottom line: for folks in Texas, it is not time to panic, but it is
time to prepare. Determine, if you don't know already, whether you're
in an evacuation zone. The rule of thumb is "run from the water, hide
from the wind," so unless you're in a storm surge zone, a flood plain,
a poorly constructed home, or quite close to the shore, you can, and
probably should, plan to hunker down rather than get the hell out. But
don't listen to me — listen to your local authorities. And if you are
in an evacuation zone, make the necessary preparations to leave
tomorrow or Thursday, if and when the order comes.

Again, listen to the local authorities on this: if they tell you to
leave, you should leave. Ike is nothing to trifle with. As I've said,
it may, for a variety of reasons, prove to be something less than a
disaster — and if this happens, it will not mean the storm was
"overhyped," it will just mean you got lucky. Be grateful, if so. But
you should not play Russian roulette with this storm. Yes, previous
hurricanes have made lucky turns. Yes, last-minute weakening often
happens, and is possible here. But those fortuities are not
guaranteed. Take Ike seriously.

__________________________________________________
To subscribe/unsubscribe or for help with using the mailing list go to
http://www.rhodes22.org/list
__________________________________________________