Weaker than expected Atlantic hurricane season ends

Dec 01, 2013
This October 27, 2013 NASA satellite image shows Hurricane Raymond churning in the Pacific Ocean off Mexico.

The 2013 Atlantic hurricane season officially ended on Saturday as the quietest since 1982 and the sixth least active since 1950, the US National Oceanographic and Atmospheric Administration said.

Thirteen tropical storms formed since early June in the Atlantic but only two, Ingrid and Humberto, reached hurricane strength.

While the number of named storms topped the historical average of 12, the number of hurricanes was well below the historic average of six medium-strength category one or two storms and three major category three storms and above.

Category three hurricanes have wind speeds of at least 110 miles (178 kilometers) per hour, while a category four storm can pack winds of 130 miles (210 kilometers) per hour or more. The most damaging are category five storms with winds of at least 155 miles (250 kilometers) per hour.

NOAA had predicted in May that 2013 would be more active than usual, with 13 to 20 tropical storms, and three to six hurricanes.

"This unexpectedly low activity is linked to an unpredictable atmospheric pattern that prevented the growth of storms by producing exceptionally dry, sinking air and strong in much of the main hurricane formation region, which spans the tropical Atlantic Ocean and Caribbean Sea," said Gerry Bell, NOAA's lead hurricane forecaster.

"Also detrimental to some this year were several strong outbreaks of dry and stable air that originated over Africa."

A study published in June in the British journal Nature Geoscience, found that a drop in the frequency of tropical storms in the north Atlantic during the 20th century may have resulted from human activity through the production of aerosols, tiny chemical particles suspended in the atmosphere.

Aerosols may affect the formation of clouds and more importantly act as a screen to reduce the ocean's surface temperatures, thereby reducing the heat that fuels tropical storms.

The work of Nick Dunstone of Britain's Met Office showed that storms and hurricanes were less frequent in the north Atlantic during periods of high concentration of aerosols over the region.

Conversely, the study found that measures since the 1980s to tackle pollution and improve air quality reduced levels of aerosols—and in turn ramped up hurricane activity.

And they anticipate that Earth-warming greenhouse gases will exert more influence on the frequency of tropical storms than aerosols.

Other studies have linked climate warming to an increase in intensity of tropical storms.

While the United States emerged largely unscathed from the season this year, Mexico was hit by five and three hurricanes. Three of the storms originated in the Atlantic and the other five in the northeast Pacific, NOAA said.

Explore further: Hurricane season ends with no Atlantic basin storms

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User comments : 7

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orti
2.4 / 5 (14) Dec 01, 2013
Seems the climate does what it does – not what models predict, not what media talking heads and websites say, not what alarmists hope for, and not what big governments dictate.
runrig
3 / 5 (6) Dec 01, 2013
Seems the climate does what it does – not what models predict, not what media talking heads and websites say, not what alarmists hope for, and not what big governments dictate.


A quite predictable post. Try looking up the difference between seasonal forecasting ( long term weather ). And climate forecasts.
ryggesogn2
1.4 / 5 (9) Dec 01, 2013
Quite predictable:
"And they anticipate that Earth-warming greenhouse gases will exert more influence on the frequency of tropical storms than aerosols."

Read more at: http://phys.org/n...html#jCp
runrig
3.4 / 5 (5) Dec 01, 2013
Quite predictable:
"And they anticipate that Earth-warming greenhouse gases will exert more influence on the frequency of tropical storms than aerosols."

As you're repeating yourself: I will too. From other ongoing Hurricane thread..

A seasonal hurricane forecast is forecasting long term "weather" and models are unable to give accuracy because of that. Though apparently they've had a lot of success.
http://[url=http://coaps.fsu.edu/hurricanes

Response to warming is an average over time. No regional weather will ramp up incrementally - just as neither does temp.
runrig
3 / 5 (2) Dec 01, 2013
site editing error
runrig
3.4 / 5 (5) Dec 01, 2013
Quite predictable:
"And they anticipate that Earth-warming greenhouse gases will exert more influence on the frequency of tropical storms than aerosols."


As you're repeating yourself: I will too. From other ongoing Hurricane thread..

Hurricanes are "weather" and yes predictions are flawed because of that. Though apparently they've had a lot of success.
http://coaps.fsu....rricanes/forecast-archive]http://coaps.fsu....-archive[/url]

Hurricanes' genesis are a complex interaction of many things within the extra-tropical atmosphere and as such are chaotic. Climate models do not include internal chaos – and only the ignorant or wilful would compare a seasonal f/c against a general warming physical truth.

"The basic premise of seasonal forecasting of tropical cyclones is related to the idea that tropical cyclones activity is closely tied to characteristics of the large-scale atmospheric circulation, sea surface temperatures (SSTs), vertical wind shear, and low-level vorticity."
http://coaps.fsu....rricanes
runrig
3.7 / 5 (3) Dec 01, 2013
The sites editor is playing a blinder!

http://coaps.fsu....-archive
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Dec 02, 2013
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