[freedomtowernight_edited.jpg] 26th Parallel: Katrina and Mis(perceptions)

Monday, August 29, 2005

Katrina and Mis(perceptions)

WARNING: Weather-related rant upcoming, brought to you by the 26th Parallel Weather Department. No one in particular is being targeted here (well, OK...perhaps a small group of people with the initials MSM), just the misperceptions raised by Katrina's move across South Florida last Friday.

Much has been said here in South Florida about the "unexpected turn" Katrina made towards Miami-Dade County. A common refrain I've heard is, "I thought it was headed for Broward County (Ft. Lauderdale area)"!

For anyone who is even remotely familiar with our geography, one can see that Broward and Miami-Dade counties border each other. That means that, if a hurricane is expected to "hit" Broward County, a resident of Miami-Dade County can deduce one of two things: 1) The hurricane will pass very close to Miami, and therefore be felt there in some form, or 2) The hurricane may veer ever so slightly from its exact projected path which is never 100% correct, and hit Miami head-on.

Let's take a look at the weather maps, shall we?



This is the forecast issued by the National Hurricane Center at 11 AM Wednesday. The blue and pink line along SE Florida is a Tropical Storm Warning and Hurricane Watch. This means that hurricane conditions are possible within 36 hours. Notice the infamous skinny black line going from east to west. That the exact forecast track of Katrina, with the big white "cone" representing the error cone. That line is pretty close to Miami, right? The white cone covers all of South Florida, meaning that the track could pass anywhere within that area.

Let's move ahead 12 hours:



This is the forecast from 11 PM Wednesday. Notice the line along the coast is now red. This means a Hurricane Warning is in effect for all of SE Florida, including Miami-Dade County. A Hurricane Warning means that hurricane conditions are expected within 24 hours. The skinny black line still looks pretty close to Miami, and most of Florida is under the white cone. Are we safe here in Miami? Don't think so.

Katrina made landfall near the Broward/Miami-Dade county line about 6 PM on Thursday, within 24 hours after the warning was issued. The actual track took Katrina southwest across the northern half of Miami-Dade county, resulting in an error of about 15-30 miles from the forecast issued 24 hours prior. That's about the distance that most of us travel to work every morning. A hurricane is a system that covers several hundred miles.

Schools were closed in Miami-Dade county that day, so local officials had a good idea of what might happen.

So then, why were so many people caught by surprise? Was it because it was stronger than expected? No, the forecast called for a category 1 hurricane, and that's exactly what we got.

Was it a lack of perception of what a category 1 storm can do? Maybe. Here's the definition of category 1 hurricane and what kind of damage one can expect from a storm of that magnitude:

Winds 74-95 mph (64-82 kt or 119-153 km/hr). Storm surge generally 4-5 ft above normal. No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damage to poorly constructed signs.

Except for the storm surge, that describes exactly the type of damage which occurred over South Florida as a result of Katrina.

So I'll ask again, why were so many people caught by surprise? The experts weren't, and conveyed this very clearly in the advisory which was issued Wednesday at 11 PM. Read the entire message, especially the part about the hurricane warnings and the expected rainfall.

My conclusion:
Many people did not take the storm very seriously because it was a category 1. Imagine if this would have been a cat 3 or 4 with the same exact forecast track. People in Miami would have been freaking out days in advance.

My other conclusion is that too many people listen to the talking heads in the media (not all media did a bad job, but generally speaking) more than they do to the experts or local officials who were warning people in Miami all along that this would happen.

3 Comments:

Blogger Henry Louis Gomez said...

While agree with your overall point, Robert, I'm going to disagree on a couple of particulars. First of all on the forecasted track of the storm. The "cone of death" has become a joke to most of who live down here because it always shows that there's chance the storm could hit you no matter where you are in the southeast. No I'm exagerating a little, but only a little. The other thing is that when the thing made landfall up in the Ft. Lauderdale area most people assumed it would do what most storms do and turn north. It eventually did but not after dodging south and then west into the gulf. We've been conditioned to believe if the storm hits north of us, that it will only get further away towards the north. Obviously these things are very unpredictable. I remember hearing about a hurrincane that went right through downtown Miami, across the peninsula, into the gulf where it did a 180 and came back through it's original path.

As far the destruction goes, since this storm kind of popped up off the coast (as opposed to the ones that are tracked all the way across the ocean from western Africa) people didn't really have time to put up all their shutters. I think most people felt their house could handle the kind of wind that were forecast and we were right. The wind damage wasn't too bad. What really wreaked havoc was the amount of water that saturated the ground. The biggest trees that fell, only fell because the ground in which their roots were, was completely saturated. They toppled over under their own weight.

11:45 PM, August 29, 2005  
Anonymous Anonymous said...

The 50 foot Oak tree branch that landed on my roof didn't do so because it was saturated. Though I seem to have escaped any serious damage (my house was built in 1952, back when they knew how to build houses) it reminded me not to take those things for granted.

I love the shade my trees provide(d), but really, I should get them trimmed back further.

The 10 or so powerlines that were down in my neighborhood all fell because of wind-on-tree-on-line damage.

You're absolutely right about the ficus trees and the ground saturation. Had a guy die a few blocks away because the nitwit was out driving in the storm and got nailed by falling ficus.

12:15 PM, August 30, 2005  
Blogger Henry Louis Gomez said...

I had the top of tree sheared off so yes there was wind damage, but it wasn't the type of hurricane andrew, debris flying around, wind damage. I saw a bunch of those ficus trees that were toppled and uprooted and I have to believe it was the water in the ground. Assuming there had been the same wind but no water, those trees could not have fallen.

4:33 PM, August 31, 2005  

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