Typhoon Wutip, a powerful tropical cyclone in the Pacific Ocean, surpassed Typhoon Higos as the strongest February typhoon on record just two days ago. The journey since then, hasn't been all that great. Wutip has now moved into a very hostile environment allowing it to weaken rapidly back to a tropical storm. One of the major factors to Wutip's rapid decrease in strength was the presence of what meteorologists call wind shear.
Before we get into how wind shear affects tropical cyclones, let us first dive into what exactly wind shear is. Wind shear as defined by the National Oceanic and Atmospheric Association (NOAA) is the variation of the wind's speed or direction over a short distance within the atmosphere. Typically wind shear is most observed in the higher latitudes of the atmosphere as well as close to the jet stream (30,000 feet). But, it also plays a major role in the strength and structure of tropical cyclones.
A favorable environment for a tropical cyclone would be an area where ocean temperatures are at or above 80° F and little to no wind shear. When wind shear is not present, the low pressure center has the best opportunity to become vertically aligned from the surface all the way up to the upper-levels of the atmosphere.
Tropical cyclones are known as heat engines. They are powered by the large amount of heat energy released by the warm water of the ocean. With a vertically aligned center of circulation, the flow and transport of this heat is uniform throughout the entire system. This will not only allow the tropical cyclone to stay in tact, but for further strengthening to occur.
As we saw from Typhoon Wutip, it entered a section of the Pacific Ocean where no wind shear was present allowing it to rapidly strengthen into a category 4 typhoon. Then after undergoing an eyewall replacement cycle (ERC), it would further strengthen into a powerful category 5 hurricane with 1-minute sustained winds of 160 mph and have a minimal central pressure of 915 millibars.
However, in an environment where wind shear is present, a storm’s core structure becomes vertically tilted instead of vertically stacked. A vertically-titled system will have a much higher level of difficulty drawing in the warm moist air from the ocean. This decreases the chances for the system to develop and strengthen. Wind shear basically rips the tropical cyclone.
Sometimes to the point where the low-level circulation can be seen spinning across the ocean's surface by satellite. Wind shear tore apart Hurricane Lee (2018) saving Hawaii from a catastrophic situation. And now we are seeing wind shear take it's toll on what was Typhoon Wutip. Below is a current satellite image of what was Typhoon Wutip as well as the outlook provided by the Joint-Typhoon Warning Center. A tropical cyclone that was once a powerful category 5 typhoon, has now been stripped of it's thunderstorm activity due to strong wind shear aloft.
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© 2019 Meteorologist Joey Marino