LifeSecure recently sat down with Meteorologist Mark McGinnis from Fair Skies Consulting to ask some pressing questions from our readers following the publication of our blog, What We Can Learn from Hurricane Harvey.
1. What are some facts about Hurricanes that not many people know?
Hurricanes and tropical storms impact areas far from the Atlantic Ocean and the Gulf of Mexico. Now, clearly, our coastline is impacted more than inland areas. On the map below is the track of every tropical system from 1851 to 2017. Here are a couple of takeaways. If you live on the United States coast from Texas north to Maine, you live in an area impacted by hurricanes. Second, as hurricanes move inland and weaken, they have impacted areas far from the ocean; like Nebraska, Wisconsin, Illinois, and Michigan. These inland impacts can include flooding and severe weather – tornadoes and damaging winds.
Figure 1 Atlantic Tropical Tracks 1851-2017
2. What are the most aggressive dangers Hurricanes often produce?
There are two: extreme wind and water. Let’s focus on wind first. The most destructive winds within a hurricane are found in the eyewall. The eyewall is a circle of thunderstorms that surround the eye of the hurricane. Below is a satellite picture of Hurricane Florence with the eyewall highlighted by a red circle I added.
Figure 2 Satellite of Hurricane Florence
It is within this small area that the most intense winds of a hurricane are found. When the eyewall reaches the coast, significant to catastrophic wind damage is possible based on the intensity of the hurricane.
The strong winds and lower pressure in the eye of a hurricane can pile water as the hurricane approaches a coastline. This area of abnormally high water is called the storm surge. Storm surge fluctuates with each hurricane, but the primary factors that build storm surge are wind speed, low pressure, momentum, coastline shape, and shallowness of the coast. Our stronger hurricanes like Katrina and Camille had storm surge over 20 feet. When water is this deep and moving quickly, buildings are totally destroyed and people drown. Storm surge is the number one killer in hurricanes. Here are some before and after pictures of storm surge.
Figure 3 Picture courtesy of the United States Geological Survey
The other aspect of water is flooding rain. As we saw in Houston with Hurricane Harvey and in North Carolina with Hurricane Florence, when a hurricane, or any tropical system – tropical depression, tropical storm or hurricane, stalls, tremendous amounts of rain can fall. In the case of Harvey and Florence, record-setting and life-threatening rains resulted. Harvey set the Texas state record for rainfall and the United States rainfall record for most rain from one storm – over 5 FEET! In September 2018, Florence set rainfall records in North and South Carolina. The map below contains the rainfall records from tropical systems for each of the lower 48 states.
Figure 4 State Rainfall Maximums from Tropical Systems
3. How accurate are weather predicting systems in the 2010’s?
The National Hurricane Center produces all official forecast products for tropical systems in the Atlantic Ocean and the Eastern Pacific Ocean. These forecasts are for the benefit of the citizens of the United States and all countries in the tropical Atlantic basin. This includes our neighbors in Central America, Canada, Mexico, the Caribbean islands, Bahamas, and Bermuda. Tropical forecasts have improved significantly over the last 30 years. As research continues and we learn more about tropical systems, we can more accurately understand and predict their movements. The forecast path improvement is quite noticeable in figure 5. This chart analyzes forecast track errors over time. Note how the slope declines from left to right on all time periods.
Figure 5 Average Track Errors 1970 to 2010
For example, the 72-hour forecast (yellow line) had a forecast error of 450 miles. So, the three-day forecast was typically 450 miles off – not very good. In 2010, the same 72-hour forecast was reduced to 125 miles. The 24-hour forecast (red line) error in 1970 was over 100 miles and by 2010 reduced to less than 50 miles.
The intensity forecast has not seen a similar improvement. There is still much to learn regarding all of the processes involved with tropical system intensities. Figure 6 shows the forecast error tracked over time. There is improvement, but it is at a much slower rate.
Figure 6 Forecast Intensity Errors
These improvements in tropical system forecasting save lives. The National Hurricane Center works very hard at improving the science and communications of tropical forecasting. Thankfully, it is working. Check out this link.
It is every forecast for Hurricane Florence – from the eastern Atlantic Ocean to North Carolina. It visually shows the consistently accurate Florence forecasts.
With more than 20 years of severe weather forecasting and communications experience, Mark McGinnis is a true authority in forensic meteorology. As the founder and owner of Fair Skies Consulting, LLC, McGinnis provides his customized services as a Certified Consulting Meteorologist.
In a hurricane, severe storm, or flood you may have to evacuate or shelter-in-place with the aid of hurricane survival kits. Water-related disasters, such as hurricanes, storms, and floods are among the most common types of emergencies. It is important to have a hurricane kit, a storm kit or a flood kit in order to be prepared. Severe hurricanes and storms can force people to shelter in place for hours, days, or even weeks. Hurricane kits include emergency supplies such as breathing protection, first aid, water and food, light and communication tools, and more to get you through a storm and the aftermath of a storm.