Frequently Asked Hurricane Questions: Understanding The Science Of Prediction And Preparation In South Florida - South Dade News Leader: Community News | South Dade News Leader | Miami Dade County

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Frequently Asked Hurricane Questions: Understanding The Science Of Prediction And Preparation In South Florida

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Posted: Friday, June 26, 2015 12:00 am | Updated: 2:14 pm, Tue Jun 30, 2015.

  A lot of questions are often asked before the beginning of each hurricane season.

However, as residents of the most frequently hit area in the United States, South Floridians have a unique perspective on these powerful storms and interesting questions that go along with them. The following ten questions have been consistently brought up by South Floridians during the ‘Canes on ‘Canes outreach talks, and I would love to share them with you.

Q: If a hurricane is approaching Florida, is there a way for humans to modify hurricanes to steer them away from land or at least weaken them before landfall?

A: Many people do not realize that the first attempts to weaken hurricanes occurred almost 70 years ago. In 1947, Nobel Prize winning chemist, Irving Langmuir, and a team of researchers from General Electric started Project Cirrus and dropped 180 pounds of dry ice into a storm off the coast of Georgia. The basic idea behind the dry ice was to cool the storm and slow the release of energy. Less than twenty years later, the U.S. Navy and the National Oceanic and Atmospheric Administration (NOAA) funded Project Stormfury in an effort to make hurricanes weaker. As part of Project Stormfury, silver iodide was used to seed clouds just outside the eye wall. The theory held by the scientist was creating clouds in a disadvantageous spot in the hurricane would steal energy from the storm. The results of both studies were inconclusive. Additionally, the thought of accidentally steering a powerful storm from one country to another sounds like a recipe for international strife.

  Other techniques for weakening storms have been suggested but a common problem with all of them is the massive size and intensity of hurricanes.  Hurricanes can cover hundreds of thousands of square miles of ocean and use the energy from the warm waters over this entire area. A simple back-of-the -napkin calculation indicates that we just do not have the means to take away enough energy from these storms to even make a dent.  The NationalHurricaneCenter notes that a hurricane releases heat energy at a rate of 50 trillion to 200 trillion watts. This is the equivalent of a 10-megaton nuclear bomb exploding about every 20 minutes. To put things in perspective, the largest nuclear bomb on record is only 50 megatons. So dry ice, bombs, and other energy depleting techniques are simply not an option.

Q: Why have you not shown the seasonal forecast for hurricanes in your presentation? How many hurricanes can we expect in Florida this year?

A: We never show the seasonal forecast during our presentations for three main reasons. The first reason is these forecasts rarely improve upon what the long-term average tells us. Several scientific studies have shown that the average number of hurricanes in past years is almost as good of a guide as the pre-season specialized forecasts produced by weather agencies across the world. The second is these forecasts do not incorporate a prediction of hurricane landfalls. There are complicated weather systems that affect the direction storms travel during the season, and these systems are impossible to anticipate more than a week in advance. As a result, there can be active seasons like 2010 with 19 named storms and zero U.S. hurricane landfalls. There can also be quiet seasons like 1992 with only seven named storms but one of the most deadly and costly U.S. landfalls ever (Hurricane Andrew).  The third and most important reason for excluding seasonal forecasts from our presentations is the fact that it only takes one storm to create a disaster.  Sometimes, the general public loses sight of the fact that there is a weak correlation between the number of hurricanes in the AtlanticBasin over a season and the amount of damage experienced by the U.S. Hurricane disasters can come at any time so it is best to always be prepared.

  In reference to what we should expect in Florida this year, it is important to look at the historical landfalls in our area and not read into recent seasons. Since 1851, 58 hurricanes have passed through south Florida (land between TampaBay and Key West). That is an average of one hurricane landfall per less than three years. Therefore, the long hurricane drought we have been experiencing does not mean anything for future years. Every year we are equally, and very likely, to deal with a hurricane, and recent active or inactive years have not been shown to affect our chances.

Q: What is the difference between typhoons in the Pacific Ocean like the 200 mph Haiyan and strong hurricanes in the Atlantic Ocean like Andrew?

A: Hurricane Andrew and Typhoon Haiyan are the same weather phenomena and the same physical laws that are used to explain them. More specifically, the Atlantic and Northeast Pacific term “hurricane” is the same as a “typhoon” in the Northwest Pacific and a “cyclone” in the South Pacific and Indian Ocean. Note that the umbrella term tropical cyclones is often used to describe all of these systems as well as tropical depressions and tropical storms.

Q: I noticed that I am not in one of the evacuation zones assigned by the Florida Division of Emergency Management (DEM). Does that mean I should be fine to “ride out” the storm no matter what?

A: The short answer is no. These zones are extremely useful but are defined only by potential storm surge events caused by a hurricane. NOAA defines storm surge as an abnormal rise of water generated by a storm, over and above the predicted astronomical tide.  However, the winds and rainfall totals associated with strong hurricanes present hazardous situations even if you are distanced from the coast, floodplain, or a river.  Even if you are generally unaffected by a storm, the damage around you could leave you without adequate resources to get you through the devastation that follows. Major hurricane landfalls have resulted in power and clean water loss that can last over a month. Therefore, it is important to pay attention to the guidance of local authorities, especially when your area is under a hurricane warning. Reviewing FEMA’s evacuation tips (http://m.fema.gov/during-hurricane) are also a good guide.

Q: Isn’t the hurricane forecast cone always wrong for south Florida? In recent years, the cone has been over us and the storm has missed us.

A: The NationalHurricaneCenter forecast cone is designed for a hurricane to travel outside the cone 33% of the time. In other words, the cone is supposed to contain the center of the storm only two out of three times. The last five years of errors at each forecast time (12-120 hours) are used for the drawing of the cone. Lets say from 2010-2014, two out of three storms are forecasted at 24 hours to be at least 50 miles away from where the storm actually travels  and at 48 hours, the errors are at least 80 miles for 2 out of 3 storms. This information is all you need to make your own 48-hour cone. It is important to remember how this cone is made and what its purpose is. The forecast cone provides a general guide for where the center of the storm will be located. However, a hurricane is felt well outside the cone even if the center stays inside the cone. But remember, we should only expect the storm to stay in the cone 2 out of 3 times.

Q: Are we getting better at forecasting hurricanes?

A: In recent years, both intensity and track forecast errors have decreased but track forecasts have improved at a much faster rate. Since the cone is based on the past five years of track forecast errors, we can see this improvement with a smaller cone. The 2009 cone uses 2004-2008 data and the 2015 cone uses 2010-2014 data. Notice how the smaller errors make a smaller cone.

Q: I heard it’s an El Nino year. Does that mean no hurricanes in Florida?

A: During El Nino years, there are about 2 named storms less in the entire AtlanticBasin compared to an average year. This drop in the number of storms is caused by higher wind shear values throughout the Caribbean and Gulf of Mexico during El Nino years.  Wind shear describes how the winds change with height and when surface winds are blowing at a different speed or direction than winds aloft, it is not good for storm development. However, having less storms on average does not prevent hurricanes from affecting Florida during El Nino years. In fact, 1992 was an El Nino year where we experienced Hurricane Andrew.

Q: It’s now August and we have not seen any hurricanes. Does that mean it is going to be a quiet hurricane season for Florida?

A: Since 1851, south Florida (area between TampaBay and Key West) has only experienced two hurricanes in June and two hurricanes in July. However, there have been 13 hurricanes in August, 17 hurricanes in September, and 23 hurricanes in October. The season is just getting going in August so a quiet June and July does not mean anything for the season as a whole.

Q: How will climate change affect hurricanes in Florida?

A: This is a frequently discussed topic and the short answer is we don’t know. Recent studies have suggested that the future climate will have less frequent storms but stronger hurricanes. Although these studies indicate these results have a high level of uncertainty.  One thing is for sure is the sea level is rising along the coast of Florida. If sea levels continue to rise with climate change, then the storm surge impacts associated with hurricanes will surely worsen.

Q: The water has been warmer than average off the coast of Florida and it has not rained a lot lately. Does that mean there is more moisture and ocean heat available for hurricanes?

A: These local conditions in Florida are such a small piece to the larger puzzle of hurricane strengthening and formation. There have been no scientific studies that have proven these pre-season conditions in and around Florida are correlated with more storms and stronger storms. Global atmospheric patterns and large-scale weather systems have been shown to affect hurricane season activity much more than local weather.

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