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HURRICANE SEASON 2005
Deconstructing the most active Atlantic hurricane season on record
In case you hadn't noticed, the 2005 Atlantic hurricane season has been the most active on record. (Heck, hurricane season ended on December 1st, but try telling Hurricane Epsilon that, as he meandered out in the Atlantic until the 8th.) The facts: there were 26 named storms -- breaking 1933's record of 21. Thirteen of 'em became hurricanes, which beat 12 in 1969, and seven became major hurricanes. Katrina, Rita and Wilma all reached Category five intensity, with maximum sustained winds of 175MPH, which is the first time five Category 5 storms happened in one year since 1851. We cornered Surfline's East Coast forecaster Mike Watson and asked him what the heck was going on and what's to come.
Hurricane season 2005 will certainly go down as one of the epic seasons in East Coast history -- even if it was a twisted season, with so many major hurricanes making landfall in heavily populated areas while sending out perfect surf. This is precisely why hurricane season is a double-edged sword, especially for the Gulf Coast states. I could go over each swell event in detail but that has already been done in the links below. Rather, I'd like to throw out some relevant information on these beasts and further speculate on just what we can expect over the next few years. You see, I was born and raised in Florida, the undisputed hurricane capital of the Atlantic Basin. Florida's been nailed by more hurricanes -- almost twice as many -- than any other state. Here is the complete state by state list.
So what happened this year? Why so many storms -- and landfalling storms at that? There are six ingredients necessary for tropical cyclone (TC) formation:
1) warm sea surface temperature (SST's)
2) sufficient middle and upper level relative humidity
3) conditionally unstable atmosphere
4) light vertical shear
5) a low level pre-existing disturbance (such as a tropical wave)
6) Coriolis force (this is why storms do not form near the equator).
On any given day, the first three conditions are met in the tropics. However, we also saw plenty of four through six as well this season. Our old buddy El Nino, the culprit for many of those years with minimal activity due to increased upper level shear was a non-factor; the shear across the basin remained relatively light all season long. The other big players -- warmer than normal SSTs across the Atlantic Basin, storms forming on the western edge of the basin close to home, not much in the way of storm disrupting, dry Saharan air masses, and upper level steering current pushing these storms towards the west. Add this up and everything came together for one hell of a bang. Add in that so much of the U.S. coastline is inhabited by a large number of folks -- everything is in place for large losses of both life and property.
But isn’t global warming to blame for stronger storms? While many media sources and others want to make a direct link to global warming and stronger storms -- especially with the scientifically controversial article by Kerry Emanuel of MIT in the journal Nature -- but there is still simply not enough evidence to make such a giant leap. One major flaw in this work is the fact that Emanuel, by his own admission, obtained exaggerated results for the Atlantic Basin from faulty methodology.
Also, previous scientific research done by Emanuel and by others indicates that one degree centigrade of SST increase would translate to a 5-10% increase in TC wind speed. However we have seen only a 0.5 degree centigrade warming of the SST, which translates into a 2-3% increase in hurricane wind speed, certainly not very significant.
Well then, isn’t global warming to blame for the increased amount of storms? Not really. Rather, the number of storms occurring in the Atlantic Basin has been found to be cyclical over a number of decades; this can be seen here.
That is, we see a 20- to 30-year cycle of hurricane activity with periods of decreased activity
and periods of increased activity. A number of factors are at work here. Subsurface currents, or thermohaline circulation, vary over a 30-40 year span, which directly affects the upper ocean heat content of the Atlantic Basin. There are also large-scale atmospheric oscillations, as well as some good old fashion timing. All of this together becomes the more plausible scientific explanation for the increase in hurricane activity in the Atlantic Basin over the last few years. In science -- and in particular meteorology -- it's rarely one thing or the other that produces a result. It is more likely a combination of a few variables that come together to produce the results that we observe.
Anyhow, what does this mean for us East Coast surfers? Well, more storms mean more chances for epic summer surf seasons along the East Coast. Again, this all started in 1995, that epic year with 19 storms. But how can we forecast if we will indeed see another busy season? Well the only sure bet that we know will have an impact on our hurricane season is ENSO.
ENSO is the El Nino-Southern Oscillation made up of two phases -- El Nino (warm phase) and La Nina (cold phase). We also have the neutral state, which is what the Pacific has seen over the last year. When we see El Nino show up in the Pacific, we know that the hurricane season will almost always see a diminished amount of tropical cyclones. Conversely when La Nina is present we typically have a busier than average season.
The reasons for this is pretty simple -- the warm phase of ENSO results in increased convection or thunderstorm activity over the Eastern Pacific. The outflow aloft from this activity flows into the Atlantic Basin resulting in our tropical cyclone-killing vertical wind shear. The cold phase has the exact opposite effect; convection in the East Pacific becomes suppressed, and thus the vertical wind shear over the Atlantic becomes much weaker through the course of the season.
Other than some indications from ENSO, nothing is a sure bet in forecasting the number and especially the intensity of these storms months ahead of time. In fact, we struggle to forecast these systems just days ahead of time. You see, nobody's really figured out the mechanism for storm genesis (formation). Sure, we can see tropical waves as they move through the Atlantic but the specific reasons for whether a storm will form or not are just not known.
I also belong to a private tropical storms forum with today's biggest experts in the field including William Grey, Kerry Emanuel -- basically the who's who of the tropical research and meteorology field. By the amount of debate (sometimes somewhat heated) about this and previous hurricane seasons -- and especially at the end of this one -- lends proof to just how much is not known about tropical cyclones.
On one hand we wait all year for hurricane season, sometimes forgetting or just not realizing the potential destruction that these storms may cause, sometimes to our own families and friends. However, we easily can put that in the back of our mind the very first time we paddle out in that first punchy tropical swell of the season as some storm meanders (hopefully) out in the Atlantic Ocean. --Mike Watson
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SURFLINE'S 2005 HURRICANE SEASON COVERAGE:
HURRICANE DENNIS
July 5th-11th; max sustained winds: 150MPH; estimated damage: $1.84 billion
SURFNEWS:
Florida's Gulf Coast
Texas
HURRICANE EMILY
July 11th-21st; max sustained winds: 150MPH; estimated damage: ongoing
SURFNEWS:
Florida Panhandle
VIDEO:
Florida Panhandle: Quicktime
et_blank">Florida Panhandle: Windows Media
Surfside Texas: Quicktime
Surfside Texas: Windows Media
HURRICANE IRENE
August 4th-18th; max sustained winds: 105MPH; estimated damage: a few broken boards
SURFNEWS:
Outer Banks
Northeast
VIDEO:
Outer Banks: Quicktime
Outer Banks: Windows Media
More Outer Banks: flash
North Northeast: Quicktime
North Northeast: Windows Media
HURRICANE KATRINA
August 23rd-30th; max sustained winds: 175MPH; estimated damage: $80 billion -- costliest hurricane in US ever
SURFNEWS:
Florida's Gulf Coast
VIDEO:
Florida's Gulf Coast
More Gulf Coast
HURRICANE OPHELIA
September 6th-18th; max sustained winds: 85MPH; estimated damage: $1.6 billion
SURFNEWS:
Florida and North Carolina
Northeast
HURRICANE RITA
September 18th-25th; max sustained winds: 175MPH; estimated damage: $9.4 billion
VIDEO:
South Padre Island, Texas: Quicktime
South Padre Island, Texas: Windows Media
HURRICANE WILMA
October 15th-25th; max sustained winds: 175MPH; estimated damage: $14.4 billion
SURFNEWS:
Northeast
Secret Gulf Coast
Florida Panhandle
Miami
VIDEO:
Texas: Quicktime
Texas: Window Media
Miami: Quicktime
Miami: Windows Media
New York: Quicktime
New York: Windows Media Player
NW Florida: Quicktime
NW Florida: Windows Media
NW Florida 2: Quicktime
NW Florida 2: Windows Media
NW Florida 3: Quicktime
NW Florida 3: Windows Media
NW Florida 4: Quicktime
NW Florida 4: Windows Media
HURRICANE EPSILON
November 29-December 8; max sustained winds: 85MPH; estimated damage: none
SURFNEWS
Northeast
Puerto Rico
MORE SURFNEWS
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