Each year two sources, the National Oceanic and Atmospheric Administration’s (NOAA) Climate Prediction Center and Colorado State University’s Tropical Meteorology Project offer hurricane predictions. These predictions are broken down into three regions, the Central Pacific, the Eastern Pacific and the Atlantic. There are three important factors that enter into hurricane forecasts. First, ocean water temperatures should be higher than average. Next, weak upper level winds should be present, as strong winds aloft can tear a storm apart, regardless of the water temperature. Finally, El Nino conditions (warm water off the west coast of South America) discourage the formation of hurricanes in the Atlantic. Hurricanes are more likely in the Atlantic when La Nina conditions (cold water off the South American coast) are present. Regardless of the number of storms predicted, the location where hurricanes make landfall cannot accurately be predicted because they are dependent on current conditions.
Probabilities are broken down into three categories: above normal, near normal and below normal. For the Eastern and Central Pacific zones below normal activity is predicted for this season. The forecast for the zone most important to Marco Island, the Atlantic zone, predicts a 65% chance for above normal activity. No El Niño is expected this season, and the water temperatures are above normal in the Atlantic. It is estimated that the Atlantic Zone will have 12-18 named storms, 6-10 hurricanes, and 3-6 major hurricanes (category 3 or above) based on 105-200% ACE (Accumulated Cyclone Energy). The ACE index measures wind speed at the time of storm formation and every six hours for all named storms, which is a much more accurate way to estimate hurricane activity than just the number of named storms.
Larry noted that, “On Marco Island we are a little less prone to hurricanes than other parts of Florida. Winds in our latitudes go from east to west, so dangerous hurricanes tend to strike the east coast of Florida first and weaken as they go 100 miles across the Everglades.” Hurricanes thrive on latent heat fed by deep warm water and dissipate quickly when they go across land, even moist land like the Everglades.
Wilma was a very unusual hurricane, hitting Marco Island directly from the west. It occurred late in the hurricane season, and a winter system had set up and the jet stream had moved south like a deep ‘V’. The jet stream absorbed the storm and westerly winds steered Wilma in this direction.
Larry explained the recent devastating tornadoes are cyclical in nature. “We may have storms hitting urban areas this year versus agricultural areas, thus the season seems worse. These days, we have more spotters and cameras giving us visuals. Tornadoes in Joplin and Tuscaloosa were very strong, but I can’t say if we are having more severe tornadoes or if the tornadoes are just hitting more urban areas. Like the flooding along the Mississippi, it’s not unprecedented.”
The floods on the Mississippi this year were a rare occurrence. Larry pointed out that, “After the 1927 floods, President Hoover developed the most sophisticated water management system along the Mississippi, spearheading dams, diversions, levees, and spillways to keep the populated areas safe. It may be hard to imagine, but the Mississippi flows at 2,000,000 cubic feet per second! During high flood periods, that water drains out through the Atchafalaya River and swamp rather than down the Mississippi. The reason the spillway was opened was to prevent flooding in more populated areas like New Orleans and Baton Rouge. Heavy snow in the Upper Midwest and rapid snow melt are likely contributing factors to this year’s Mississippi River flooding.”
“Civilization inadvertently alters climate. The population of Phoenix went from 100,000 to 3,000,000 in 50 years. With more concrete, glass and steel reflecting heat, higher temperatures are now occurring in Phoenix than any time in the recent past. Even if we’re not certain that humans are causing global warming, we can be pretty confident that humans do impact the local climate significantly.”