Back in January, on January 1rst in fact, the first cyclone of this year’s Eastern Pacific Typhoon season formed. It would be one of at least 52 tropical depressions, storms, and typhoons that would rake through this vulnerable region over the next 11 months — resulting in over 7,000 deaths and tying a record for the most storms set 49 years ago in 1964.
The typhoon season that would repeatedly rake the Phillippines with monster storms and disgorge the strongest cyclone — Haiyan — to ever make landfall came on, at least in part, due to anomalously hot Pacific Ocean waters. Throughout the year, a large swath of the Western Pacific remained between 2 and 5 degrees Celsius above the 1979-2000 average. This stretch of water reached 90 degrees Fahrenheit during the summer of 2013, contributing to the extremely hot air mass that set off temperature record after temperature record in southeastern China from late July through early August.
According to reports from NOAA, not only was this mass of water very warm, its warmth extended far into the depths of the Pacific. NOAA’s report: Deep Warm Water Fuels Haiyan Intensification linked the anomalously deep and hot water to Haiyan’s rapid intensification as well as provided a basis for understanding why so many cyclones had formed during the, very prolific, typhoon season of 2013.
(Anomalously hot and deep Pacific Ocean waters detected by NOAA sensor in early November)
The intensification of Super Typhoon Haiyan is being fueled by “ideal” environmental conditions – namely low wind shear and warm ocean temperatures. Maximum sustained winds are currently at 195 mph, well above the Category 5 classification used for Atlantic and East Pacific hurricanes. Plotted here is the average Tropical Cyclone Heat Potential product for October 28 – November 3, 2013, taken directly from NOAA View. This dataset, developed by NOAA/AOML, shows the total amount of heat energy available for the storm to absorb, not just on the surface, but integrated through the water column. Deeper, warmer pools of water are colored purple, though any region colored from pink to purple has sufficient energy to fuel storm intensification. The dotted line represents the best-track and forecast data as of 16:00 UTC on November 7, 2013.
It will only take the formation of one more cyclone to break the all-time record number of storms formed back in 1964. With 6 cyclones having formed since Haiyan ripped through the Philippines in early November and with Pacific Ocean temperatures remaining anomalously hot, it appears possible that 2013 will break this long-standing record.
For years, researchers have debated whether increasing ocean heat content due to human caused global warming will result in more numerous tropical cyclones. Heat is the primary driver for the formation and strengthening of these storms and with average global temperatures increasing at the rate of at least .2 degrees Celsius per decade, that driver continues to strengthen. At the very least, researchers agree that the strongest storms will likely be stronger. But tropical cyclone formation is complex and other factors, such as large areas of dust stirred up from expanding deserts, may also act to suppress storms in a warming world, at least in some basins.
One factor that has not been explored in depth is what appears to be a steadily growing length of hurricane seasons. In almost all basins, storms appear to be forming earlier and earlier in the year. Climatological peaks for typhoon seasons are still occurring at the usual time. But the warming oceans appear to be setting the stage for year-round tropical cyclone formation. A tropical cyclone typically needs water temperatures of at least 75 degrees (Fahrenheit) to form. And with pools of water at this temperature and above expanding even during what is typically winter it would seem that the basic ingredients for year-round storm formation are steadily being provided.