BIRMINGHAM, Ala. (WIAT) _- Today, the National Oceanic and Atmospheric administration released their outlook for the 2014 hurricane season. In a word, it might be an “average” season. They project between 8 to 13 tropical storm will form, of which 3 to 6 may become hurricanes and of those between a 1 and 2 may become Category 3 or higher. As always, this stab at the season doesn’t say where or when these storms will occur. Of course, there is always the caveat that “just one storm” could leave a lasting impact on a coastline where it makes landfall. The projection, as always, is based on many factors which are known to influence any given season, mainly, the temperature in the Atlantic Ocean and the status of the variable weather pattern known as El Niño. Hurricanes develop in warm water, but tend to thrive when the right upper-level winds are favorable. Here is the way El Niño influences the latter part of that equation:
Every few years, there is a noticeable change in the average temperature around the Equator in the Pacific Ocean. We can observe this because there are buoys there measuring the ocean temperatures; tracked by scientists. A prolonged period of higher than normal temperatures leads to an El Niño, whereas cooler than normal signal La Niña. The name comes from the time of year when this begins to be observed; around Christmas. When the temperatures are warmer than normal, a higher number of thunderstorms form in the Pacific, which alters the shape and strength of the band of high-speed, high-altitude winds known as the Jet Stream. During an El Niño season, those higher winds blowing across the Atlantic disrupt growing tropical systems by increasing the amount of shear aloft. Think of a chimney: if you block the top of a chimney, the rising smoke stops rising and eventually, the fire below goes out. If there’s nothing to impede it, the smoke keeps rising. Higher wind speeds aloft essentially chops the tops off rising warm air, feeding storm development. This is not to say there won’t be any storms, but they will have a harder time getting going. During a La Niña as was the case from 2008-2011, there is less wind shear and storms develop and form more easily.
It is important to note that El Niño seasons have produced some of the most memorable storms in history. During the 1983 season, Alicia hit the Texas coast knocking out skyscraper windows in Houston and leaving the fourth largest city without power for nearly a month. Only four storms formed that summer, and all were hurricanes during that El Niño year. Hurricane Andrew, the last Category 5 storm to hit Florida occurred in 1992, another El Niño year which only produced 7 storms overall, with four becoming hurricanes.
Predicting how many storms will form is involves some guesswork and doesn’t always pan out. Take last year, for example. The seasonal forecast called for another active year, following the trend of the previous three. However, the final tally of 14 named storms and two hurricanes fell well short of the forecasted values of 13-20 named storms and 7 to 11 hurricanes. The fall-off was due to a cooler than expected Atlantic ocean and higher than normal wind shear over the Atlantic. The latter occurred in the absence of an observed El Niño.
Either way, when storms are present, one of the tools used to study these systems is the hurricane hunter. This modified C-130 departs from Biloxi, Mississippi, flying into hurricanes to collect information for future forecasts. Storm Track Chief Meteorologist Gene Norman has flown on that plane during several storms and knows first-hand how the dedicated team on board, collects and interprets crucial data. “I actually assisted in the launching of dropsondes”, he recalls. “It looks like a potato chip can, but it has special sensors that measure temperature, wind and pressure. It’s shot out of a cannon down into a storm, sending back data in real time as it falls.” That information is then fed back to the National Hurricane Center to be processed and input into computer models. Without the crucial information about the current location of the storm, accurate projections can’t be made.
What’s it like to “on board” during a flight? “At times, it’s quite tranquil”, says Norman. The plane flies several hundred feet above the surface, analyzing the moist atmosphere feeding the storm, maxing criss-cross paths through this highest winds. “That’s when it can get real bumpy – I came close, but never lost my lunch”.
In addition to the Hurricane Hunter, the National Weather Service is considering using drones to fly into storms as a cost-saving measure when storms are far from land and pose no real threat. Hopefully, the projection of a “quiet” season pans out, but as Norman cautions – “It only takes one storm to leave a lasting memory.”