2008 Atlantic Hurricane Season has begun

[Fig]

Another year, another hurricane season that starts early.

Although in this case, "early" means "May 31 over June 1". It still makes the first time we've had two consecutive year with at least one tropical or subtropical storm since we've begun keeping track.

(Yes, I missed my cue. Been busy)

-------

The Atlantic Hurricane season, which (nominally) lasts from June 1 to November 30 of every year, is the period of time in which hurricanes are expected to form in the Atlantic. As we did in 2006 and 07, this is the thread for the new hurricane season.

(See post below for an explanation of how hurricanes and the hurricane season work. I don't want to clutter the first post - which will have information about the actual 2008 season - with the summary).

This year, most predictions (which have been a little hit-and-miss lately - way under the mark in 2005, way over it in 2006, and somewhat off in 2007 go with an average to above average hurricane season.

This means, in number, 12 to 16 named storms, 6 to 9 hurricanes, and 2 to 5 major hurricanes.

The names we'll been using for this year will be :

Tropical Storm Arthur (Late May-Early June, Yucatan Landfall, 9 deaths, 78 m$ damage)
Major Hurricane Bertha (C-3, Early-Mid July, Bermuda Near-Miss, 3 deaths, minimal damage)
Tropical Storm Cristobal (Mid-July, No landfall, no death, minimal damage)
Hurricane Dolly (C-2, Late July, Texas landfall, 22 deaths, 1.5 B$ damage)
Tropical Storm Edouard (Early August, Texas landfall, No death, Unknown damage)
Tropical Storm Fay (Mid-August, Hispaniola, Cuba, and Florida, and Florida, and Florida, and Florida landfalls, 36 deaths, unknown damage)
Major Hurricane Gustav (C-4, Late August, Haiti, Cuba and Louisiana Landfall, 107 deaths to date, significant damage to date)
Hurricane Hanna (C-1, Early September, Bahamas landfall, Hispaniola near-miss, Carolinas landfall, 537 deaths, Unknown Damage)
Major Hurricane Ike (C-4, Early September, Cuba Landfall, Galveston Landfall, 177 deaths, 202 missing, 31.5 B$ damage)
Tropical Storm Josephine (Early September, No landfall, no deaths, no damage)
Kyle (C-1, Late September, Nova Scotia landfall, New Brunswick landfall, 4 deaths, 14m$ damage)
Tropical Storm Laura (Late September, No landfall, no deaths, no damage)
Tropical Storm Marco (Early October, Yucatan landfall, No deaths reported, damage unknown) (Smallest tropical cyclone on record)
Tropical Storm Nana (Active, Mid-October, No landfall predicted, No deaths yet, No damage yet, )
Major Hurricane Omar (C-3, Active, Mid-October, Virgin Islands landfall predicted, No deaths yet, No damage yet)
Tropical Depression Sixteen (Mid-October, Honduras landfall, no known death and damage)
Paloma
Rene
Sally
Teddy
Vicky
Wilfred

 

[Fig]

For those of you joining us (not that I expect many, but...), here is a brief summary of the process leading to hurricanes forming.

Generally, a hurricane begins life as a group of large moisture clouds or thunderstorms over the tropics - a "Tropical wave". As these waves evolve and move over the ocean, they will either dissipate, or begin to organize - that is, the clouds and storms merging together into one large area of bad weather formed around one area of low atmospheric pressure.

When that happens, we have a tropical depression. As the tropical depression moves around (usually) over the ocean, it will draw heat and moisture from the warm water on the surface, strengthening, and begin rotating around a central point. The stronger it grows, the more visible the central point - the eye - becomes from space ; if it grows strong enough, with clearly defined features, it may eventually become a hurricane.

If not, it will return to a tropical depression, then eventually become a remnant.

A lot of tropical storms or hurricanes stay out at sea. Others get around to hitting land ; this is called landfall. Most hurricanes make landfall

In the Atlantic, the United States National Huricane Center is in charge of tracking hurricanes. The US Navy assists in this. They use a variety of computer models to predict how storms may evolve.

As with any other weather forecasting system, this is a bit of a touch-and-go affair : short-term predictions (the next day or three) tend to be pretty good predictions, but longer-term predictions tend to be a little off as often as not, and perhaps more often than not.

When a tropical wave begin to show signs it may become a tropical storm, the navy will call it an INVEST. This is the first sign we usually get we may have a storm about to form.

When a tropical wave actually becomes a tropical depression, the National Hurricane Center (NHC) will assign it a number - these numbers go in order. So the first tropical depression of the year would be Tropical Depression One, the second Tropical Depression two, etc.

If the tropical depression keeps growing, the NHC will eventually upgrade it to a Tropical Storm, and give it a name. The name comes from a list of twenty-one names, each starting with a different letter of the alphabet (there are no Q, U, X, Y or Z names on the list). If we run out of such names, letters from the greek alphabet (Alpha, Gamma, Beta, etc) will be used instead.

Once a tropical storm grows yet stronger, the NHC will upgrade it to a hurricane. There are five categories of hurricanes; one is the weakest, 5 the strongest. Hurricanes of category three and above are refered to as "Major hurricanes".

After the end of the season, the world meteorological organization will meet and review the season, as well as requests from various countries to have storm names retired.

Storm names are retired when a storm was particularly lethal or damaging (although a country has to request it, and the requesting country has to have been affected by the storm). When a storm name is retired, it will never be used again, and another name will replace it the next time this year's list is used.

USEFUL DEFINITIONS

Eye
The eye is a small area of apparent clear weather in the middle of a hurricane's cloud system.

Invest
An invest is an area of the Atlantic where the Navy's weather forecasting services feel there is a risk of hurricane formation. It's generally the first sign we have there are serious chances of a storm forming.

Landfall
Landfall refers to the EYE (or center, for those storms without eyes) of a hurricane touching ground. Thus, if it's said that a hurricane made landfall in south carolina, that means the eye of the hurricane came overland in South Carolina. Since storms and strong winds extend far from the eye, it's possible for a hurricane to cause damage and casualties without ever making landfall, if the eye remains just offshore.

Organization
Organization, with regard to tropical storm, refers to how the various smaller thunderstorms and storm clouds that form the tropical depression/storm/hurricane interact together. The more closely linked (ie, "better organized") they become, the more effective they are at transfering heat (which is what wind is), and the stronger the storm. Losing organization, for a storm, generally means becoming weaker.

Storm Surge
A hurricane, when it moves over the ocean, causes the waters of the ocean to rise toward the eye of the hurricane. When the eye come close to the coast, especially when it makes landfall, this cause rapid and significant flooding (somewhat similar to tidal waves) of the affected region. The storm surge is one of the most damaging portion of a hurricane : hurricane Katrina of 2005 had a storm surge of up to 25 feet, which was the primary source of the damage suffered.

Subtropical
A subtropical depression or storm is a weather system that acts a lot like a tropical depression or storm, but with some significant differences due to forming over water. Subtropical storm did not use to be counted as tropical storms and receive names, but now they do. They tend to not be quite as effective at transfering energy as their tropical counterparts.

Tropical Depression
A tropical depression is a weather system where clouds and storms have grouped together to form one large storm area. It has yet to acquire the typical "spiral" form of hurricanes, or their eyes, and has winds of less than 38 miles per hour (62 KMH). Typically, tropical depressions tend to have comma-like shapes.

Tropical Storm
A tropical storm is a tropical depression that has become better organized. It has now begun to acquire hurricane-like characteristics, such as a more spiral-like form. Tropical storms generally have winds of up to 73 MPH. (117 KMH). Once a weather system becomes a tropical storm, it gets a name. Tropical storms can be quite deadly, even if they are weaker than hurricanes ; tropical storm Allison killed about 50 and caused for several billions in damage in 2001 in Texas.

-Hurricane
A hurricane is a tropical storm that has become further organized, and now has wind of 74 MPH or above. They are subdivided in five categories ; the last three of which are called major hurricanes. Hurricanes tend to have a well-defined spiral forms (the stronger they are, the better defined) with a clear eye in the middle.

Category 1 hurricanes have winds up to 95 MPH. Category 2 goes up to 110 MPH. For major hurricanes, category 3 goes from 111 to 130 MPH, Category 4 from 131 to 155, and anything stronger is a category 5 hurricane.

Wind Shear (sometime simply shear)
Wind shear is the difference in wind strength between different altitudes. Since hurricanes occupy a large area vertically as well as horizontally, large differences between winds five hundred meter above five kilometers above sea level and ten kilometers above can result in a tropical depression, storm or hurricane becoming disorganized (the wind break up the clouds), and therefore beginning to weaken.

Tropical Wave
A loose gathering of storm clouds around an area of low pressure in the tropical atlantic sky. If the storm clouds begin to form together and organize, a tropical depression or worse may form.

USEFUL LINKS

http://www.nrlmry.navy.mil/tc_pages/tc_home.html - the Navy's hurricane page. This is where invests are announced.
http://www.nhc.noaa.gov/ - the National Hurricane Center
http://www.wunderground.com/blog/JeffMasters/show.html - Jeff Master's tropical weather observations blog at Weather Underground
http://en.wikipedia.org/wiki/Hurricane - The Wikipedia page about hurricanes. Generally more detailed than my summary above.
http://en.wikipedia.org/wiki/2008_Atlantic_Hurricane_Season - Wiki's page about the 2008 Atlantic Hurricane Season

 

[The Big Al]

Models are showing another storm forming and heading for the Gulf. We'll have to see how that pans out it's been persistent in the model forecasts.

 

[Fig]

Meanwhile if the scattered remnants of Arthur meander just a little bit further south than they're forecast to they might actually reenter the Pacific. Wouldn't that be fun?

(Seeing as Arthur itself was born from the remnants of Pacific tropical storm Alma)

 

[The Big Al]

Bertha is with us and making it's way across the Atlantic. They have been taking it out to sea but recent forecasts have been shifting farther west. It's quite possible that if it stays fairly week it could slip under a trough and menace on the Eastern Seaboard.

 

[Amewsment]

Very interesting information you posted here, do you follow hurricanes in your free time or do you do it professionally?
Anyways I think this year's hurricane season will likely be worse than last year's season as that was rather tame, much to the surprise and dismay of Pat Robertson xD

 

[Fig]

I follow it in my free time.

And actually, last year's season was not so tame - we did have two category-five hurricanes, plus a devastating category-one storm that hit Haiti.

It's just none of them hit the United States.

 

[Amewsment]

And actually, last year's season was not so tame - we did have two category-five hurricanes, plus a devastating category-one storm that hit Haiti.

My comment was in reference to the situation in the United States of America as I do not know of the exact situation in the Pacific for example and thus the reason I mentioned Pat Robertson.

 

[Fig]

Oh, I was just talking about hurricanes in the Atlantic. It's just they hit Latin America.

That said, signs show recreation break may be over. Bertha seems set to hit Hurricane force, and on a ramming course for the Carolinas/Virginia area.

Of course it still has wiggle room. On the northmost possible track it could well attempt the Canada run and piss off Nova Scotians. The southmost track could be ugly - IIRC the Gulf is pretty warm by now, and the last thing we want is a Gulf Buster.

Still, my early predictions as it stand - and it is still very early, with lots of room for the hurricane to wiggle - is a category 1 or 2 storm making a Cape Hatteras run.

EDIT : Category 1 or 2 may be underestimating. sea temps off the Carolinas are around 27-28. Bad news.

 

[Fig]

Luckily, it seems Bertha will turn to the north sooner than we originally thought. It's going to brush Bermuda, but otherwise only harm a few fishes.

Which is just as well, since it is now a hurricane.

 

[The Big Al]

Holy shit. Bertha is not just the first hurricane of the season but now the the first MAJOR hurricane of the season. She strengthened right past Cat 2 into a Category 3. It's not expected to last but damn.

 

[Fig]

Good God.

It's always a little scary, too, when the < in <1% in front of "Category 5" vanishes.

 

[Rayne]

But it's still just at 1% right? I'm not scared of 1%.
Trajectories point it northwest, and Big Bertha has plenty of growing room with the warm Bermuda seas. Bertha is not looking very friendly to the East coast right now. I really hope a high pressure system is hanging out around here come Saturday.


[btw good hurricane info Damian]

 

[Fig]

And after lulling everyone into a false sense of security by slipping all the way back down to a puny little Category 1 Bertha over the past few days, Bertha bust back onto the scene with a jump back to Category-2.

Odds are very strongly in favor of a return to C-3 in short order - 61% odds it will be back at three in twelve hours.

And the odds of a C-4 are getting seriously non-negligible, hitting the double-digits in 36 hours. C-5 hits 2% shortly.

 

[Fig]

Well, Bertha just played one mean trick on Bermuda - stall and intensify right next to them.

Got to say, I think henceforth we should look at whatever NHC predict for Bertie, and expect it to do the exact reverse.

 

[Fig]

Another hurricane season, another record fall.

Quoth the NHC : ...BERTHA NOW THE LONGEST-LIVED JULY TROPICAL STORM IN HISTORY...

That, incidentally, was on the evening of July 15. Bertha shows no signs of wanting to die off just yet, and will in fact hit the two-weeks mark with the very next advisory.

Mind, two weeks is still just halfway to the actual all-months record, which is a whooping 28 days. Bertha probably won't make it there, but has fair odds of making the global top-10. #10 is currently Hurricane Ivan of 2004, at 18 days, 18 hours.

 

[Fig]

And, meanwhile, oblivious to all the talk, Bertha quietly decided it was more interesting to be a hurricane after all, and is now quietly refusing to come back down to a proper tropical storm. This is, what, the tenth time that Bertha goes out of her way to say Red when the NHC says Blue?

Right now the NHC calls for Bertha to head off in the general direction of Iceland, but that's what the NHC says. The way Bertha as been going, I expect her to head east, ransack the Azores, pass through the straight of Gibraltar, and make landfall somewhere in the vicinity of Tel Aviv as a Category 5 Hurricane. (That's what *I* predict because it's 100% made off of predictions the NHC would never make in a thousand years)

At the same time, a new tropical depression - Tropical Depression three - is now active off the southern parts of the Carolinas, and generally making its way alongside the coast. Could well hit Tropical Storm strength, but unlikely to do much more.

 

[The Big Al]

Christabol has been joined by Dolly. Dolly has more of a potential to cause problems as she heads in the general direction of Texas. While it's possible she will strengthen to Hurricane strength she's expected to hit as a strong tropical storm. But first she gets a whack at the Yucatan.

 

[Fig]

Dolly is now in the Gulf, which means we have a guaranteed landfall on schedule. Should be at low Hurricane strength per NHC.

New possible area for development off the coast of Africa. We're certainly having an active July.

 

[Fig]

Not QUITE Hurricane season, but relevant enough, the latest XKCD webcomic went for hurricane humor

http://xkcd.com/453/

I like Hurricane Where-the-Hell-is-Bermuda. It's Bertha!

And of course, Hurricane Freud is a worthy heir to Rita :-D