Hurricanes are among the deadliest and most damaging weather phenomena on Earth. However, in 2021, they remain a mystery – and it is difficult to predict. People are usually given only minutes to take cover from winds that can exceed 400 miles per hour. It is one of the most frustrating and stagnant problems in meteorology. why?
Hurricanes are relatively common in the central part of the United States, averaging about a thousand per year. The area known as Tornado Alley, from central Texas to eastern Nebraska and Iowa, is hardest hit, especially during the months of April, May, and June.
Hurricanes also sometimes occur in our country. However, there is a significant difference: they are less powerful here. But in the United States, hurricanes are a serious problem and they are getting worse. Global warming is causing more and more deadly tornadoes, and they are increasingly occurring in a wider area than in the past.
Direct link to global warming
In a recent study, James Elsner of Florida State University described how hurricanes become more powerful. And the increase in hurricane strength is significant: 5.4 percent annually from 1994 to 2016. His findings are backed by official storm reports from US weather agencies, all of which show an upward trend in hurricane strength and also indicate that hurricanes are taking increasingly longer time and wider paths.
The study shows a direct link between warming and the number and strength of hurricanes: a combination of increased heat and humidity, available potential energy by convection (CAPE) and increased wind shear. Simply put, when heat, humidity, and erratic winds converge at the highest levels, you get stronger tornadoes.
Conditions that cause hurricanes will be facilitated by a variable jet stream. Due to the rapid warming of the Arctic, the difference in temperature between the north and south has narrowed. This reduces pressure differences between the arctic and mid-latitudes, and softens the winds of the jet stream.
Just as slow-flowing rivers usually follow a meandering path, the slow-flowing jet stream also tends to meander more. Large north-south ripples in the jet stream generate energy in the atmosphere. Incidentally, it’s the same process that was also responsible for the polar vortex that hit the United States earlier this year.
More and more intense, but hardly any progress in predictions in the past ten years
In recent decades, tornadoes have changed, too – they are relatively less common in Oklahoma, Texas and Kansas, and are the traditional Alley Tornado, but are more common in Illinois and other states along the Mississippi River and east.
More and more severe, however, and this is an additional problem, and therefore not better to predict. exactly the contrary. In 2011, the average time people got tornado warnings was about 13 minutes. But now that’s down to 8.4 minutes. Think about it: If you have less than nine minutes to prepare, what else can you do?
It’s not that we declined to predict – there are more hurricanes. But no real progress has been made in the past ten years. This lack of progress in hurricane warnings is frustrating when you consider how adept meteorologists are at predicting other severe weather, including tornadoes. In 2019, the National Hurricane Center’s forecast three days before the storm were more accurate than the 1990 forecast one day before.
Why is it so hard to predict?
Why is it difficult to predict when a hurricane will occur? Scientists know that tornadoes mainly consist of massive and violent thunderstorms, especially violent storms that spin like small tornadoes. These storms are especially common in the central and southeastern parts of the United States, where warm moist air from the Gulf of Mexico meets dry air from the western and southwestern mountains. They will form mainly in the spring and early summer.
The problem is that meteorologists can look at two giant thunderstorms that look identical, and only one of them will cause a tornado. This is also why the false alarm rate of tornado warnings is so high: forecasters can’t easily tell when a storm that looks like it might trigger a hurricane will actually do it.
Scientists understand the ingredients needed to create the kind of supercelled storms that produce the most powerful tornadoes. There are four. You need a lot of moisture in the atmosphere and a lot of wind shear, or changes in wind speed and direction (this creates a storm). You also need atmospheric instability, which can cause air currents, and upward or upward movement of air which rotates around the storm along a vertical axis.
But what causes a hurricane occurs on a much smaller scale – perhaps at the level of individual particles in the atmosphere – and is strongly influenced by the characteristics of local geography. Even trees can disrupt surface circulation, unlike grasslands, and this can affect hurricane formation. Weather conditions that lead to a tornado in Oklahoma will not necessarily cause a tornado in Alabama.
We don’t even know how that happens
Many storms even produce rotating winds without creating an actual hurricane. The question meteorologists are trying to solve is, how, when and why these rotating winds move to a point where you have a very narrow, intense vortex that we call a hurricane.
It is possible (but not counterintuitive) that tornadoes form from the bottom up. They will start as a turbulence on the ground and then connect upwards with a thunderstorm. Being a small vortex on the surface comes into contact, for whatever reason, with the rising current in a thunderstorm. And then you get an effect like a snowboarder spinning: she pulls her arms in, stretches and spins faster and faster.
But it’s also possible for tornadoes to descend from a storm cloud – or a combination of both. It looks like a tornado is forming all the way from top to bottom in one go.
And now, scientists don’t know. why? Currently, weather radar cannot get a good glimpse of the rapid conditions at a relatively low altitude that lead to tornadoes. The processes that determine whether tornadoes form or not appear to occur on a time scale of a minute or less, only tens of meters from the surface, an area that is difficult to scan with radar.
The solution still looks like science fiction at the moment
The only way to improve hurricane forecasts, researchers say, is to take it head-on. Hurricane forecasts have become very good in recent decades because scientists have been able to study their every move intensely. It helps that they move slower than hurricanes and last for days. We can fly planes in and out of a hurricane’s eye wall and collect all kinds of data.
On the other hand, tornadoes are smaller and short-lived. The scientists who study don’t have that wealth of data to take into account their predictions. To make matters worse, tornadoes easily damage scientific equipment. Any kind of sensor is often destroyed before they can sample whatever it is you hope to collect. So it is very difficult to get a complete data set for the phenomenon.
What we need is another hack. One that makes it possible to model and simulate every molecule of the atmosphere. Such molecular modeling may sound like science fiction now, but it may be possible in the future. There are specialized branches of physics where they do it literally, modeling any molecule, but usually in very small sizes, down to a cubic centimeter at most. It is a matter of expanding this capacity over time.