Where have the Northern Hemisphere Tropical Cyclones gone the last 2 years?
Upon examination of all tropical cyclone activity in the basins throughout the Northern Hemisphere for the past 2 years, a remarkable downward trend in cyclone energy has continued and reached historic levels of inactivity. Even though North Atlantic hurricane activity was expectedly above normal in 2008, the Western and Eastern Pacific basins produced considerably fewer (and weaker) than normal typhoons and hurricanes, respectively in 2008. The image below shows the previous three decades of cyclone energy (as measured by the ACE, a popular metric of climatologists used to measure hurricane energy) for all global ocean basins combined (green) and for the Northern Hemisphere (blue). Using a 24-month running sum, we see that Northern Hemisphere ACE remains at historical lows. Moreover, there has only been 1 Category 5 typhoon (Jangmi) during the past year. This cyclone activity is consistent with continued colder conditions in the Pacific Ocean and the previous strong La Nina last sprin
