Deadly late-season Atlantic hurricanes growing more frequent
What may be the final tropical disturbance in the Atlantic (94L) has fizzled, due to dry air and increasing wind shear, and there's an excellent chance that this will be final "Invest" of 2010 in the Caribbean. The 2-week wind shear forecast from the GFS model is showing a dramatic increase in wind shear over the Caribbean in the coming weeks, which should put an end to the Caribbean hurricane season. However, it's been another remarkably active November in the tropics this year. The formation of Hurricane Tomas this month marks the fourth consecutive year in the Atlantic with a hurricane occurring November 1 or later. We had Category 1 Hurricane Noel in 2007, Category 4 Hurricane Paloma in 2008, Category 2 Hurricane Ida in 2009, and now Category 2 Tomas in 2010. This is the first time since beginning of reliable hurricane records in 1851 that there have been four consecutive years with a late-season November or December hurricane in the Atlantic. The previous record was three straight years, set in 1984 - 1986. It used to be that late-season hurricanes were a relative rarity--in the 140-year period from 1851 - 1990, only 30 hurricanes existed in the Atlantic on or after November 1, an average of one late-season hurricane every five years. Only four major Category 3 or stronger late-season hurricanes occurred in those 140 years, and only three Caribbean hurricanes. But in the past twenty years, late-season hurricanes have become 3.5 times more frequent--there have been fifteen late-season hurricanes, and five of those occurred in the Caribbean. Three of these were major hurricanes, and were the three strongest late-season hurricanes on record--Lenny of 1999 (155 mph winds), Paloma of 2008 (145 mph winds), and Michelle of 2001 (140 mph winds). Of course, the number of storms we are talking about is small, and one cannot say anything scientifically significant about late-season Atlantic tropical cyclone numbers, unless we include storms from late October as well. This was done, though, by Dr. Jim Kossin of the University of Wisconsin, who published a 2008 paper in Geophysical Research Letters titled, "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is an "apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high". The recent increase in powerful and deadly November hurricanes would seem to support this conclusion.
Figure 1. Damage on St. Lucia from Hurricane Tomas. Image credit: St. Lucia Star.
Deadly late-season Atlantic tropical cyclones are growing more frequent
In the 500+ years people have been encountering hurricanes in the Atlantic and recording these encounters, we are sure of only twenty November and December storms that have caused loss of life. If we restrict our time window to the past 70 years, when we have a fairly reliable data base of hurricane mortality thanks to the yearly storm summaries published in Monthly Weather Review, we find only ten late-season storms that killed people. Of those ten, seven occurred in the past twenty years, including the second deadliest late-season tropical cyclone on record, Hurricane Gordon of 1994, which killed 1145 people on Haiti. Only the Great Cuba Hurricane of 1932, which killed 3107 people in Cuba, the Cayman Islands, and the Bahamas, was a deadlier late-season tropical cyclone. Hurricane Tomas ranks as the 6th deadliest late-season hurricane since 1851 in the Atlantic. The storm left 30 dead or missing on Haiti, at least nine dead on St.Lucia, two on Curacao, and one in the Virgin Islands. The storm has caused hundreds more indirect cholera deaths in Haiti, by spreading contaminated water.
Figure 2. Number of days a named storm existed in the Atlantic during November and December between 1950 and 2010. Years when an El Niño event occurred are not included, in order to make the plot smoother (El Niño events tend to dampen Atlantic hurricane activity during all portions of the season.) There has been a general increase in late-season tropical cyclone activity over the Atlantic in recent decades.
The increase in deadly late-season storms in the past twenty years is primarily a Caribbean phenomena. Only two deadly late season hurricanes have affected the U.S. in the past century: Hurricane Kate of 1985, which killed five in Florida, and the 1925 Florida Hurricane, which hit southwest Florida as a Category 1 hurricane on December 1. This remarkable storm was the latest landfalling hurricane in U.S. history, and killed 60 people.
Resources
Kossin, J., 2008, "Is the North Atlantic hurricane season getting longer?", Geophysical Research Letters, Vol. 35, L23705, doi:10.1029/2008GL036012, 2008.
A list of the 20 deadly late-season tropical cyclones: http://www.wunderground.com/hurricane/deadly_nove mber.asp
My blog post, Is the Atlantic hurricane season getting longer?
Next post
I'll have a new post on Friday.
Help support Portlight.org's efforts to bring some Christmas cheer to the kids of Haiti, by donating to their Christmas in Haiti campaign.
Jeff Masters
Reader Comments
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writing my first article for the Evansville Examiner (:
I am so glad for you :O)..
Thanks!
I will once it is completed, and I'll post the link on my blog as well. I will regularly post a link to my articles there so they can be found easily
Tornado Dude will be publishing for the Evansville, IN Weather Examiner. His URL will be: http://www.examiner.com/weather-and-climate-in-evansville
I also write for the Ft Worth Weather Examiner and my URL is: http://www.examiner.com/weather-and-climate-in-fort-worth
Cold Black Friday Morning
At least it won't snow in Ft Worth on Thanksgiving..I better not say that too loud or our fickle "La Nina" may change her mind, again!
thanks Bob! (:
With this La Nina, what you saw last year will be very unlikely to happen again this year.
You are welcome. I know you will do a GREAT job..
Thank you Jesus..We will have wild temperature swings though :O)
I didn't read past the front page. I don't know details such as how they take into account the vanishing arctic sea ice (3 years, my estimation, in case someone, ahem, is keeping records of predictions). I also don't know the political bias of Science Daily (but they are merely referencing anyway).
Still, with Turkey day coming and winter settling in everywhere I thought it might be of interest.
I'm not sure that mortality figures are the best way to compare changes in hurricane activity. There could be many reasons why storms are deadly apart from intensity.
Haiti is vulnerable to heavy rainfall because of deforestation, which leads to faster runoff and more flooding from less precipitation; it is also poorer and more densely populated than 50 years ago – more people are vulnerable because they take greater risks to survive and have fewer options about where to live and/or shelter in a storm.
There are also more people in the world – is a larger percentage of the affected population dying? How good, how accurate and consistent is the data over the "500+ years people have been encountering hurricanes in the Atlantic and recording these encounters"? Even in the past 70 years?
Mortality has more to do with preparedness and response. It doesn't always follow wealth – compare mortality from Hurricane Andrew in the Bahamas and the US: 3 direct and 1 indirect deaths in the Bahamas (one hit by flying debris and another drowned because too intoxicated to climb out of the storm surge into the attic of the house where others survived (OK, I ran a hotel on Harbour Island in 1995 and the causes I report are anecdotal) another person died of a heart attack during the storm). In the US, 26 direct, 39 indirect deaths, and a response that led to restructuring FEMA and conspiracy theories of the body count.
All this to say that "more deadly" may be a good inquiry, but more data is needed!
W Schlei
Int'l School Ho Chi Minh City
P.S. This IB Geography and Theory of Knowledge teacher thanks you for providing the material for a good lesson in both courses...and on Teacher's Day, too!
All early indications are saying 2011 will be pretty active like 2010 was.
And if we go by the pattern we've been having since 2005 (Neutral, El Nino, La Nina, Neutral, El Nino, La Nina) We should either get a neutral or a La Nina in 2011 and a El Nino in 2012.
18 hours...
12 minutes...and it's over...
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
700 AM EST FRI NOV 19 2010
FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...
DISORGANIZED SHOWERS AND A FEW THUNDERSTORMS ARE ASSOCIATED WITH A
WEAK AREA OF LOW PRESSURE LOCATED OVER THE GULF OF HONDURAS...WEST
OF THE BAY ISLANDS. UPPER-LEVEL WINDS ARE NOT CONDUCIVE FOR
DEVELOPMENT...AND THE LOW CENTER IS EXPECTED TO MOVE INLAND OVER
BELIZE AND GUATEMALA LATER TODAY. THERE IS A LOW CHANCE...10
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 12 HOURS AS IT MOVES WESTWARD AT 5 TO 10 MPH. REGARDLESS OF
DEVELOPMENT...THE DISTURBANCE COULD PRODUCE LOCALLY HEAVY RAINFALL
OVER PORTIONS OF BELIZE...GUATEMALA...AND THE SOUTHERN YUCATAN
PENINSULA OF MEXICO DURING THE NEXT COUPLE OF DAYS.
ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.
..............................................
That is, unless we see a single December storm like we did in 2005 and 2007, or two December storms like we did in 2003. That's four in seven years, or roughly 57%. (And, of course, November isn't over yet.) You never know...
Either way, hurricane season 2011 starts in just 193 days, 12 hours, and 7 minutes...
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
344 AM EST FRI NOV 19 2010
VALID 12Z TUE NOV 23 2010 - 12Z FRI NOV 26 2010
A HIGHLY AMPLIFIED POSITIVELY TILTED UPPER TROUGH WILL START OFF
THE MEDIUM RANGE PERIOD ACROSS THE WEST INTO THE UPPER MIDWEST.
THIS LARGE SCALE FEATURE WILL HELP STEER TWO PAC/POLAR SHORT WAVE
FEATURES OUT OF THE WEST INTO THE PLAINS... WHILE A QUICK ARCTIC
INTRUSION INVADES THE NRN ROCKIES/PLAINS. THE FIRST SHORT WAVE
IMPULSE STARTING OFF MON IS EJECTING OUT INTO THE NRN/CENTRAL
PLAINS BUT QUICKLY LIFTS UP INTO ONTARIO BY TUES MORNING. THE NEXT
UPSTREAM IMPULSE IS ARRIVING INTO CA MON MORNING... MOVING THROUGH
THE GREAT BASIN AND LIFTING THROUGH THE CENTRAL PLAINS INTO THE
GRT LAKES TUES INTO WED. ALSO LATE MON INTO TUES... A SIGNIFICANT
SHOT OF ARCTIC AIR WILL SURGE SOUTH FROM CANADA INTO THE NRN
ROCKIES/PLAINS. ONCE THIS OCCURS... THE LONG WAVE UPPER TROUGH
SHOULD BE ON THE MOVE... SLIDING INTO THE PLAINS/MS VLY ON WED AND
INTO THE ERN THIRD OF THE COUNTRY ON THURS. THIS ALSO MEANS THEN
THE IMPRESSIVE SERN/MID-ATL RIDGE SHOULD BEGIN TO BREAK DOWN.
FOLLOWING THE AMPLIFIED UPPER TROUGH OUT WEST WILL BE A
SIGNIFICANT INCREASE IN UPPER HEIGHTS AND A SOLID RIDGE BUILDING
BY THURS/FRI. HPC FOLLOWED A BLEND OF THE 00Z ECMWF/UKMET FOR DAYS
3 AND 4... A BLEND OF THE 00Z ECMWF/GFS AND GEFS MEAN ON DAYS 5
AND 6 AND JUST THE OPERATIONAL ECMWF ON DAY 7.
MUSHER
No wabbits either!
Active 04, Active 05, Quiet 06, Active 07, Active 08, Quiet 09, Active 10, Active 11?, Quiet 12...
TSPIN BUSTED FORECAST ALIBI
And those quiet seasons tie in very well with El Nino years.
We are located at 16.1N 86.9W
Winds are from the East blowing at close to 30kts.
I hope the cold front does not cause the system to stall.
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