Atlantic hurricane season probably over; Cyclone Sidr's death toll tops 3,000

The Atlantic hurricane season officially ends on November 30, but unofficially, it is probably over. While ocean temperatures are still plenty warm to support tropical cyclone formation in the Caribbean and the Bahamas, wind shear has become prohibitive across the entire tropical Atlantic, and is forecast to remain so until early December. It is possible wind shear will fall low enough over the mid-Atlantic in early December to support tropical storm formation. Any such storm would be far out at sea, and not threaten any land areas. Ocean temperatures are continuing to cool, though, and I put the odds of such a development at 20%. In the recent active Atlantic hurricane period that began in 1995, five of the twelve years have had a named storm form after November 18. With the exception of Tropical Storm Odette of December 2003, none of these storms hit land. Odette hit the Dominican Republic as a 50 mph tropical storm, and triggered flash floods that killed eight people. Late season storms typically form in the Western Caribbean or in the open Atlantic (Figure 1). Due to the frequent number of strong troughs of low pressure marching across the Atlantic this time of year, most tropical storms move north or northeast as soon as they form.


Figure 1. Path of all Atlantic named storms that formed between November 16 and 30, 1851-2006.

Tropical Cyclone Sidr's death toll at 3,000 and rising
Tropical Cyclone Sidr's death toll has risen above 3,000, making the storm the deadliest tropical cyclone the world has seen since Hurricane Mitch hit Honduras in 1998, killing over 9,000 people. The Red Crescent aid agency is estimating that Sidr's toll could reach 5,000-10,000, based on their experience with previous cyclones in Bangladesh. Thousands of people are still missing, and communications to many hard-hit outlying islands remain difficult.

Landmark IPCC report issued
The Nobel Prize-winning Intergovernmental Panel on Climate Change (IPCC) released their final "Synthesis Report" Saturday. This massive effort, repeated just once every seven years by 2,000 of the world's top climate scientists, summarizes the current state of scientific knowledge on climate change, the likely impacts, and options for how to respond. All literate citizens of the world should at least skim the 23-page report. For those of you unwilling to do so, I'll give you a 4-sentence summary:

Human-caused climate change is very likely already occurring, and will get much more significant over the coming decades. While some regions will experience benefits, most regions will experience costly and dangerous climate change. Developing nations will suffer the most. Strong action to reduce greenhouse gas emissions by 2015 is needed to prevent the worst impacts.

Jeff Masters