Climate scientists say that global warming might result in fewer, but more intense, hurricanes. There might be more wind sheer, which would make it harder for hurricanes to form and maintain. But warmer waters will energize those hurricanes which do form. Haiyan is an example of what can happen with warmer waters when there is little wind sheer.http://robertscribbler.wordpress.com/2013/11/07/haiyan-explodes-into-190-mph-monster-now-worlds-strongest-hurricane-since-1980/
Nov. 7, 2013
Perfect symmetry. It’s a meteorological term that describes the structure of a classic hurricane. A perfect doughnut-shaped eye wall filled with clouds ranging from 50,000 to 60,000 feet height in all sectors circling swiftly around a deep and tiny central eye. In a textbook, the term perfect symmetry is innocuous. In an actual hurricane, the result is horrific.
As Haiyan did the seeming impossible and became better organized late Wednesday and early Thursday, a perfectly symmetrical eye wall developed over waters in excess of 80 degrees (F) and in an atmosphere boasting little or no wind sheer. By noon on Thursday, this perfect structure allowed more efficient evacuation of air through a deep and perfectly clear eye, pulling winds of ever-greater strength through its encircling storms. Explosive winds of a strength equivalent to a strong tornado, at 190 mph (US Navy showed 195 mph at 2 PM EDT), blasted around the storm’s center as its minimum pressure fell to 904.5 millibars — 40 millibars more intense than Hurricane Sandy (latest estimates show pressures as low as 858 mb, the lowest ever recorded).
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Very hot ocean waters ranging from 1 to 5 degrees Celsius (1.8 - 9 degrees Fahrenheit) above the 1980-2000 average throughout much of 2013 have spawned numerous severe weather events throughout the Western Pacific. On January 1rst, the first tropical cyclone of 2013 formed, not waiting even a day to begin what would prove to be an explosive, record season.
Throughout 2013, cyclones continued to form so that by November 81 cyclones had ripped through this region of the Pacific. Of this number, 38 storms were tropical depressions, 30 were tropical storms, and 13 were hurricanes. Four of these hurricanes were category 5 monsters.
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Hot Pacific Ocean waters in a region north and west of the Philippines were also implicated in a major heatwave that resulted in scores of deaths throughout China, Korea, and Japan. This unprecedented ocean heat dome resulted in highest ever recorded temperatures with records being shattered consecutively, day after day, for up to two weeks in some locations.
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As with many other extreme warming events, the regional warming seen in the western Pacific cannot be entirely separated from an ongoing global warming trend. August of 2013 boasted the world’s hottest ocean temperatures ever recorded. September 2013 tied 2005 for the hottest September on record. Extreme heating provides more energy for storms, droughts, and other extreme weather events. For each degree Celsius of global temperature increase, the hydrological cycle (the rate at which water evaporates and precipitates) increases by around 7 percent. Such an increase makes droughts more extreme even as it provides added heat and moisture fuel to increase the intensity of storms.
Many scientists are now attributing the increased strength of storms over the past decade and becoming particularly intense in recent years, to the ongoing and amplifying impacts of global warming. In this case, scientific conservatism is slowly giving way to both the observed impacts of global warming and a lengthening string of increasingly intense events that continues unabated.
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The extra depth of the warm water added further fuel for intensification because cyclones tend to churn up the water, bringing cooler water up from the deep ocean. This action tends to cause the storm to weaken over time, as it brings up cooler and cooler water or as it crosses the paths of other storms. But if water at depth is warmer, one key factor that can weaken storms is removed.
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