Thursday, August 25, 2016

Reasoning With Hurricanes

The last major hurricane to strike the Keys was Wilma in 2005 and it was pretty awful. It resembled the devastation of Katrina earlier that year (K comes before W) in New Orleans with drowned cars and evacuations of people and pets but without the violence. The storm left its mark on those of us who lived through it, just as Georges did a few years earlier in 1998, with flooding albeit on a much smaller scale. 
Hurricanes are idiosyncratic, inasmuch as they all develop and move in their own ways following some general meteorological rules and people responding to storms tend to develop their own rules, superstitions and attitudes. I think the best way to approach hurricanes is to work out a plan and then stick to it, which is hard to do if you don't have experience of dealing with these storms. I also advise against taking advice as in the end you will either evacuate for no reason which is expensive and annoying or you will sit out a storm that frightens the bejeesus out of you and in either case you only want to blame yourself not some innocent opinionated barfly who just happened to spout uninformed opinions in your hearing.
I have sat through a dozen  hurricanes over the past two decades of varying intensity from near misses to direct awful hits and because I work in the 911 center I obviously don't evacuate. I also get to observe them from the safety of the armored glass (they tell us) atop the police station. I will say that compared to other natural disasters hurricanes seem to cause a lot less loss of life than you might expect from all the hype. Property damage is usually caused by flooding or localised tornado winds embedded in the main body of the hurricane but with minimal common sense you should be able to survive a hurricane unscathed. Your home or vehicles may not be so lucky. As I recall one person died in Wilma and that was from a cardiac condition brought on by stress. I always recommend evacuation, early and with decisiveness. Load your car your pets and your spouse (and the children if you are fond of them) and bug out. Enjoy a vacation in a hotel a decent distance away and let the chips fall where they may. You will have plenty of warning and lots of time to get out if you have a mind to leave. My wife takes the dog and drives north to see friends when schools are closed as she is a teacher and she likes to get out before the highway gets jammed with traffic.
Judging how severe a storm might be is extremely difficult for the professionals in the National Hurricane Center in Miami so if you choose to stay assuming it will only be a Category One (explained further down this page) you be surprised when it gets upgraded to a Category Three and things get quite scary. Below we see a picture from NOAA of flooding caused by Wilma in 2005. North Roosevelt Boulevard is marked by the line of coconut palms:
The first warning you get comes in the form of a map with symbols to show a tropical wave that may start swirling and become a depression and then a storm and then a hurricane. The NHC offers a five day "cone" in the form of a white balloon to show roughly where they think it will go, but it's not an exact science. I show an example below taken from a few years ago on this page: National Hurricane Center If you click on the link you will see whatever is actually happening now. I also have this link in my list of sites to the left of this essay on my webpage.

One other thing that irritates the shit out of me is the assignation of gender to storms. Just because it's called Irene doesn't mean it is  a sentient being. A storm is a collection of wind and humidity and that's all. The hurricane people decided to start naming the storm for simplicity's sake and that got them into trouble. They choose names from A to Z (and double AA etc in the event there are lots, as there have been in a  few years). The names come from their families or friends and lately they have been trying to acknowledge the existence of other cultures in hurricane affected zones so you will see Spanish and French names crop up alongside Polynesian names as well. They alternate between male and female and if a storm produces death or damage the name is never used again. But a hurricane is an "it" not a he or a she. Excessive familiarity will taste pretty  dry if you watch your home get knocked down by your new girlfriend. Rant over.

Hurricanes are measured on this international scale: 

Saffir-Simpson Hurricane Wind Scale

Climatology | Names | Wind Scale | Extremes | Models | Breakpoints

The Saffir-Simpson Hurricane Wind Scale is a 1 to 5 rating based on a hurricane's sustained wind speed. This scale estimates potential property damage. Hurricanes reaching Category 3 and higher are considered major hurricanes because of their potential for significant loss of life and damage. Category 1 and 2 storms are still dangerous, however, and require preventative measures. In the western North Pacific, the term "super typhoon" is used for tropical cyclones with sustained winds exceeding 150 mph.
CategorySustained WindsTypes of Damage Due to Hurricane Winds
174-95 mph
64-82 kt
119-153 km/h
Very dangerous winds will produce some damage: Well-constructed frame homes could have damage to roof, shingles, vinyl siding and gutters. Large branches of trees will snap and shallowly rooted trees may be toppled. Extensive damage to power lines and poles likely will result in power outages that could last a few to several days.
296-110 mph
83-95 kt
154-177 km/h
Extremely dangerous winds will cause extensive damage:Well-constructed frame homes could sustain major roof and siding damage. Many shallowly rooted trees will be snapped or uprooted and block numerous roads. Near-total power loss is expected with outages that could last from several days to weeks.
111-129 mph
96-112 kt
178-208 km/h
Devastating damage will occur: Well-built framed homes may incur major damage or removal of roof decking and gable ends. Many trees will be snapped or uprooted, blocking numerous roads. Electricity and water will be unavailable for several days to weeks after the storm passes.
130-156 mph
113-136 kt
209-251 km/h
Catastrophic damage will occur: Well-built framed homes can sustain severe damage with loss of most of the roof structure and/or some exterior walls. Most trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last weeks to possibly months. Most of the area will be uninhabitable for weeks or months.
157 mph or higher
137 kt or higher
252 km/h or higher
Catastrophic damage will occur: A high percentage of framed homes will be destroyed, with total roof failure and wall collapse. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Most of the area will be uninhabitable for weeks or months.
Hurricanes' sustained winds do not reflect the force of tornado strength winds embedded in the swirling mass of vapor and this tornadoes can wreck your home and leave a neighbor almost unmolested. To prepare for the arrival of a hurricane you need to remove anything that could be uprooted and flung about like a missile in stronger winds than you have ever experienced in your life. 
So the question becomes what do you do? Well, you could choose to be hard core and throw a hurricane party and get drunk with friends as the winds build and act like you are the devil-may-care pirate of tourist myth. Or you could be like me, wondering if now is time to pull in the garden furniture and prepare for Disturbance 1  or whatever it's called, a system currently bringing rain and wind to the Northern Caribbean and Southern Bahamas. You may listen to the "never evacuate " crowd on their bar stools or you may prefer to stay and figure nowhere near as many will die as died in the recent Italian earthquake (nearly 200) nor will as many homes be destroyed as were burned in recent California wildfires and Louisiana floods (hundreds). 
We are now getting into the height of hurricane season when waters are hottest and winds are lightest giving swirling hurricanes the best chance to form and build. From now till the end of October is high season for hurricanes. I will say this: it's easy to be brave until you get up close to these things. As winds rise and seas start crashing you will realize you are losing all control over your life. When highway one is closed to inbound traffic evacuation picks up speed. When a mandatory evacuation is ordered the authorities are telling you that if you need help you won't get any. You are free to stay home but when winds reach 35 mph sustained police fire and rescue won't be dispatched to help you. Take that as your warning. Then they will announce Highway One bridges are too windy for safe travel and you are stuck. Planes have long since stopped flying, last minute evacuees have left it too late. Then you sit and wait and hope you have cut down all coconuts to prevent them becoming cannonballs. You have put up your hurricane shutters. You have food and water and pet food. 
You look around and hope all is secure. You got to stay with friends and you pass empty streets and houses barricaded as though abandoned.

A last dash for gas, and then the hunkering begins. Hunker down they say, and you do and then you learn what the sound of 135 mph winds do to your eardrums and rain pushed at windows like bullets. 

The weather reports as you hunker look like this, taken from a hurricane report a FEW YEARS AGO as an example:

And as I write we have a possible hurricane forming in the northern Caribbean quite likely bringing heavy rain this weekend and possibly even a hurricane though the odds at this point seem to indicate just a period of wind and rain for a couple of days. 

Let us presume that Disturbance 1 does take the 50% chance and decides to develop into a Category One hurricane. What to do? I dare say one will assume it will not develop into a major barn storming hurricane, say a Category Three and one stays put. This will be interesting. Most people in the Keys have never lived through a hurricane. Lots to think about suddenly.