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Tropical Cyclone Steering Change

Global warming affects large scale weather patterns and the weather systems embedded within such as tropical cyclones (also called hurricanes and typhoons). Research has documented several recent changes in tropical cyclone steering such as increased stalling and shifts toward higher latitudes.

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Climate science at a glance

  • There have been changes in virtually every measure of tropical cyclone activity in the Atlantic since the 1970s, including tropical cyclone steering.[1]
  • Models show that in a warmer climate, storms generate at higher latitudes (closer to the poles) and travel larger distances, which means storms reach their maximum intensity at higher latitudes.[2][3][4]
  • The fingerprint of human-caused climate change has been found in the slowdown, or stalling, of tropical cyclones worldwide.[5]
  • Slower-moving tropical cyclones carry bigger flood risks.[6]
  • Some areas, including densely populated coastal cities, could experience changes in risk due to larger storms moving toward the poles.[3]

Background

What is tropical cyclone steering?

The movement of a hurricane from one location to another is known as hurricane propagation. When it comes to forecasting the movement of tropical cyclones, the average winds in various atmospheric layers are the dominant "steering forces" - also called steering winds or currents. Tropical cyclones are steered like sailboats. The taller the sail, the more higher level winds can steer it, the stronger the storm, and the more it’s influenced by upper level winds. If a storm stays fairly weak, it would slide under the upper level flow and be steered by lower level winds. 

What is tropical cyclone translation speed?

Translation speed is the forward speed of tropical cyclones. Steering winds influence tropical cyclone translation speeds. A cyclone's forward speed is important because the slower a tropical cyclone moves, the longer its influence time, and the greater the impact it can have due to heavy rain and strong winds. When a tropical cyclone slows or stop, it is said to "stall". The unprecedented rainfall totals associated with the stall of Hurricane Harvey over Texas in 2017 provide a notable example of the relationship between regional rainfall amounts and tropical-cyclone translation speed.


Global tropical cyclone steering trends and climate change

  • (Zhang et al. 2020Coumou et al. 2018; and Coumou et al. 2015): Observational data indicates a general slowdown of atmospheric summer circulation in the mid-latitudes.[7][8] Models also support this pattern.[9]
  • (Kossin 2018): The forward speed of tropical cyclones - known as translation speed - has slowed globally.[5]
  • (Gutmann et al. 2018): The global slowdown of tropical cyclones has intensified tropical cyclone rainfall and may be linked to human-caused warming.[10]
  • (Studholme and Gulev, 2018): Data show a poleward migration of tropical cyclone lifetime maximum intensity in the NH of 0.1° lat decade−1 and in the SH of 0.45° lat per decade in hemispheric averages.
  • (Tamarin-Brodsky and Kaspi, 2017): Models show that in a warmer climate, storms are not only generated more poleward, but they actually also travel larger distances, which means storms reach their maximum intensity at higher latitudes. These changes are due to stronger upper-level winds and increased atmospheric water vapor.[2] 
  • (Kossin 2014): The latitude at which tropical cyclones reach their greatest intensity is gradually shifting from the tropics toward the poles at rates of about 33 to 39 miles per decade.[3]
  • (Kossin et al. 2010): There has been a substantial increase in virtually every measure of tropical cyclone activity in the Atlantic since the 1970s, including tropical cyclones steering.[1] These increases are linked, in part, to higher sea surface temperatures in the region that Atlantic tropical cyclones form in and move through.

Global studies attribute changes in tropical cyclone steering to climate change

  • (Kossin 2018): Tropical cyclones worldwide have increasingly stalled, their forward speed decreasing, over the past 70 years, due to a slowing in steering patterns attributed to global warming.[5]
  • (Baldini et al. 2016): The mean track of Cape Verde tropical cyclones has shifted gradually north-eastward from the western Caribbean toward the North American east coast over the last 450 years. Since about 1870, these shifts were largely driven by anthropogenic greenhouse gas and sulfate aerosol emissions.[4]

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Arctic Amplification
Extreme Heat and Heat Waves
Glacier and Ice Sheet Melt
Global Warming
Greenhouse Gas Emissions
Land Ice and Snow Cover Decline
Land Surface Temperature Increase
Permafrost Thaw
Precipitation Falls as Rain Instead of Snow
Sea Ice Decline
Sea Surface Temperature Increase
Season Creep/ Phenology Change
Snowpack Decline
Snowpack Melting Earlier and/or Faster
Atmospheric Moisture Increase
Extreme Precipitation Increase
Runoff and Flood Risk Increase
Total Precipitation Increase
Atmospheric Blocking Increase
Atmospheric River Change
Extreme El Niño Frequency Increase
Gulf Stream System Weakening
Hadley Cell Expansion
Large Scale Global Circulation Change/ Dynamical Changes
North Atlantic Surface Temperature Decrease
Ocean Acidification Increase
Southwestern US Precipitation Decrease
Surface Ozone Change
Surface Wind Speed Change
Drought Risk Increase
Land Surface Drying Increase
Intense Atlantic Hurricane Frequency Increase
Intense Cyclone, Hurricane, Typhoon Frequency Increase
Intense Northwest Pacific Typhoon Frequency Increase
Tropical Cyclone Steering Change
Wildfire Risk Increase
Coastal Flooding Increase
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Winter Storm Risk Increase
Coral Bleaching Increase
Habitat Shift or Decline
Parasite, Bacteria and Virus Population Increase
Pine Beetle Outbreaks
Heat-Related Illness Increase
Infectious Gastrointestinal Disease Risk Increase
Respiratory Disease Risk Increase
Vector-Borne Disease Risk Increase
Storm Intensity Increase
Tornado Risk Increase
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