DISCUSSION: In the days leading up to the peak intensity of what is now the late Super Typhoon Wutip, there is no question that there several remarkable and historical things which were especially captivating about this tropical cyclone which both formed and dissipated over in the Western Pacific Ocean basin. First off, in going to the previous article from this evening (which can be found within the “Western Pacific Ocean” section under our “Global Regions” section tab), there is a more detailed discussion regarding how Wutip was the most intense tropical cyclone to ever be observed north of the equator during the month of February over the past 70 years (or during the period of modern records). Thus, this was most certainly a very impressive tropical cyclone from a longer-term historical perspective as far as tropical cyclone records are concerned.
However, there were other quite impressive aspects of this tropical cyclone as well on top of its historic record-breaking achievements. One such facet of this storm which was quite impressive from a satellite imagery perspective were some of the neat features which were observed in association with this storm while it was at as well as near super typhoon status. While Super Typhoon was both at and near peak intensity there was a prolonged period during which there were consistent core storm-top cloud features known as “gravity waves” emanating the center of Wutip’s circulation. This is very well captured in the brief visible satellite imagery animation which was produced courtesy of the Himawari-8 satellite imager which is approximately positioned over the Western/Central Pacific Ocean basin(s). To be a bit precise, gravity waves are “ripple-like” cloud features which can sometimes form near and moving away from the center of intense tropical cyclones. They form as a direct result of intense changes in air pressure values in going outward from the eye of the storm. They are essentially a pressure-differential inner-core storm response to rapid changes in atmospheric pressure values over a relatively short distance in comparison to the overall spatial extent of the storm itself.
Thus, this just goes to show that there are often many things which can be studied from any given tropical cyclone which go well beyond the scope of the simple maximum intensity and historical context of any given tropical cyclone.
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© 2019 Meteorologist Jordan Rabinowitz
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
DISCUSSION: We may already be well into 2019 already, however, it is always important to look back on history to be able to better prepare for weather disasters which will occur in the future. In the case of Hurricane Michael which in early to mid-October of 2018, this is such a situation which deserves such an amount of due respect and appreciation for what unfolded. Even though Hurricane Michael was slow to get going as the system developed from a group of relatively disorganized thunderstorms just to the east and northeast of the Yucatan Peninsula in eastern Mexico, the future track and intensity of the storm is arguably what took most Florida and Georgia residents by surprise the most. In the case of Hurricane Michael, this tropical cyclone ended up being such a surprising tropical cyclone since it rapidly intensified much faster than was ever anticipated during most of its history making it a very bad surprise for those who were living and/or vacationing across parts of northwest Florida. Up to this point, it is believed that the storm reached a maximum intensity with 155 mph maximum sustained winds right at landfall which made it a very powerful Category 4 hurricane and with it being 1 mph short of a Category 5 storm.
In digging a little deeper into the impacts of the period both leading up to, during, and after the system’s landfall, it became evident that this storm was incredibly powerful upon seeing images and imagery of different areas which were in the path of this storm before and after it hit. For example, in the imagery attached above within the embedded Tweet (courtesy of Dr. Rick Knabb), you can see how a portion of the landmass of St. Joseph Peninsula State Park which is located just offshore from Port St. Joe, Florida no longer exists after the passage of the storm. It goes without saying that water power (and specifically storm surge from a Category 4 hurricane) is the most powerful natural force on Earth. However, it is worth noting that the power needed to destroy a portion of a coastal inlet and a corresponding beach zone such as this is immense. Thus, it just goes to show that even a relatively compact storm such as Hurricane Michael is more than capable of packing a prolific and a horrific punch on a region which can last for months and years well after the storm has come and gone.
The moral of the story here is to ALWAYS respect the natural power of a tropical cyclone and to never underestimate how intense or powerful a storm may be at landfall since that will nearly always be a factor one would never want to be faced with.
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© 2019 Meteorologist Jordan Rabinowitz
DISCUSSION: When it comes to studying tropical cyclones, there is no debate that there are several very interesting features which to mind with some of the more intense tropical cyclones which come into existence. For example, within the heart of any intense tropical cyclone is the eye of a tropical cyclone. Within the confines of the eye of a tropical cyclone there can sometimes be a series of events which unfold in such a way that there can be smaller-scale features known as misovortices which form within the center and outer portions of the eye. Most often, such microscale features can form within an eye of an intense tropical cyclone due to rapid changes in intensity which occur within the core of an intensifying tropical cyclone.
As shown in the graphic and animated Twitter graphic below (courtesy of the NOAA Satellites Twitter account), you can clearly see one such example of this as found in association with Super Typhoon Jebi back on 31 August 2018. Note how within the eye of Super Typhoon Jebi you can clearly see the presence of what appears to be a four-pointed star cloud “dancing” around the center of Super Typhoon Jebi. Such small and interesting patterned clouds form within the eye of an intense tropical cyclone as a result of incredibly small-scale wind fluctuations and minor pressure fluctuations within the center of an intense tropical cyclone. As impressive as such gorgeous misovortices are, the presence of such cloud features within the heart of a tropical cyclone are a direct indication of an incredibly intense tropical cyclone being in place and/or quickly developing when such features are present.
Thus, despite the natural majesty and beauty associated with such features within intense tropical cyclones, the underlining message here is the fact that it is imperative to always respect the natural power of such storms. Moreover, in such situations when an intense tropical cyclone is developing such features, it is essential to respect and heed the advice of local emergency officials if such a storm is heading or is expected to head in your direction.
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© 2019 Meteorologist Jordan Rabinowitz
DISCUSSION: Although it has now already been a few months since Hurricane Florence smacked into the coastal and semi-coastal sections of the Carolinas, there is still much to be gained from this event and much learning which is still yet to come in the context of furthering current and future scientific knowledge. Having said that, it is worth noting that even though a good portion of the rainfall from Hurricane Florence unfolded somewhat closer to the Mid-Atlantic coastline, there was more to the Florence flooding situation that meets the eye. For example, as shown in the animated Tweet graphic attached below (courtesy of the United States Geological Survey), rainfall gauge measurements certainly are a useful reflection of the reality which unfolded in association with the coastal approach and eventual landfall of Hurricane Florence.
Regardless of how you approach the overall evaluation of this storm, Hurricane Florence was a storm which would forever change the lives and memories of millions of people living across coastal and semi-coastal sections of North Carolina, South Carolina, and beyond. Moreover, the fact that the major flooding event which ensued and progressed further inland with time is a testament of the mammoth extent of the deep moisture which flowed inland with the landfall of the mammoth circulation associated with Hurricane Florence. This is perfectly shown in the spiking of the rainfall accumulations which is shown by way of the highlighted dots within the map along the path of Hurricane Florence. You can also see how various rainfall gauges were observed to be below or above flood stage. By scanning the periphery of this animated graphic, you can see how the flooding extended far inland from the inland which exacerbated the complications associated with rescue and recovery operations to occur in the wake of the passage of a weakening Hurricane Florence.
Thus, this animated graphic just goes to show that tropical cyclone rainfall events can (as they have many times before) extend very far inland from a given coastline and Hurricane Florence was absolutely no exception to this rule in any context. Therefore, whenever you are presented with a situation defined by an incoming flooding event which is projected to have major impacts on a given region you are living in or visiting, it is imperative to always follow the recommendations and advice of regional emergency officials.
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© 2019 Meteorologist Jordan Rabinowitz
DISCUSSION: Even though a lot of the northern hemisphere is early in the heart of the 2018 – 2019 Winter season, it is still important to take in and reflect upon various aspects of the recently concluded 2018 Atlantic and East Pacific hurricane seasons. One of the bigger issues when it comes to intense tropical cyclones which many people do not consider right away is the inherent threat with coastal beach erosion as well as overall land destruction during a close encounter or even a direct landfall. During such events, whether it be a close call or a direct strike, tremendous coastal and even semi inland damaged can often quite easily occur as a result of both the wind and storm surge associated with a powerful tropical cyclone. One such example and incredibly humbling example of this scenario unfolding happened to occur in association with Hurricane Walaka over in the Central Pacific Ocean (i.e., the Central Pacific Ocean basin being considered to also be counted in conjunction with East Pacific tropical cyclones).
Well to the north and west of the Hawaiian Islands (i.e., roughly 550 miles or so away), there is a more isolated and remote island known as East Island which was in the path of a departing Hurricane Walaka. As shown in the graphic above (courtesy of the NASA Earth Observatory), this island happened to be a remote sanctuary for local and regional wildlife from across parts of the Central Pacific. However, as Hurricane Walaka approached the island from the distance, the incoming storm surge was powerful enough (even at a substantial distance from the remote sanctuary island) to nearly completely overwhelm the associated inlets and coastal regions surrounding this island. In doing so, Hurricane Walaka proved that a given tropical cyclone does not need to even relatively close to inflict tremendous damage on an island or island chain for that matter.
Attached here is an excerpt from the original article which was published by the NASA Earth Observatory concerning the historical and ecological context behind East Island and what Hurricane Walaka meant to the situation overall:
“The Operational Land Imager on Landsat 8 captured these natural-color images of East Island on September 11 (left) and October 13, 2018 (right). The storm washed away the 11-acre strip of sand and gravel, and only two slivers of land have re-emerged since the hurricane struck. Storm surges also deposited sand and debris across Tern Island, which is northwest of East Island.
East Island is part of the French Frigate Shoals, one of the most significant coral reef systems in Papahānaumokuākea. The archipelago formed millions of years ago when a deep-sea “hotspot” created underwater volcanoes, which eventually rose to the ocean’s surface to became islands. While East Island was uninhabited by people, it provided nesting grounds for the threatened Hawaiian green sea turtles and pupping grounds for endangered monk seals, of which there are only 1,400 in the world.
Scientists believe many of the animals had already left the island before the hurricane hit because it was the end of turtle and seal breeding season. However, unhatched turtle nests were likely affected. Researchers must wait until next year to return to the islets for a more extensive survey of the impact on wildlife. In the meantime, a marine debris team worked within the Monument zone in early November to remove more than 160,000 pounds of lost or abandoned fishing nets and plastic that could endanger marine animals.
East Island is not the first island to disappear from the French Frigate Shoals. Whale-Skate Islet was lost to erosion in the 1990's, while Trig Island eroded earlier in 2018—a common occurrence in sand-dominated ecosystems. Scientists believe the mammals adapted to the ecosystem changes at Whale-Skate and Trig by finding new breeding locations, so they expect the same to happen now that East Island is gone.”
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© 2018 Meteorologist Jordan Rabinowitz
Taking a Look Back at the 2018 Atlantic Hurricane Season (Credit: NOAA NWS National Hurricane Center, NWS Key West)
Discussion: As November comes to a close, so does the 2018 Atlantic Hurricane Season. This season produced fifteen named storms. Among those fifteen storms, eight of them were hurricanes. This hurricane season produced two major hurricanes out of the eight that formed. A major hurricane is defined as a category three or higher on the Saffir-Simpson wind scale. The Saffir-Simpson wind scale measures a hurricane’s sustained wind speed.
This Hurricane season will be remembered in particular for Hurricanes Florence and Michael that caused significant damage to the southeastern United States. Hurricane Florence was one of two major hurricanes this season. It formed on August 31st, 2018 and as it made its way across the Atlantic it strengthened into a category 4 hurricane with sustained winds of 130 miles per hour. It maintained its strength until the track took the storm into an area of wind shear. Wind shear can tear apart the hurricane causing the structure to become asymmetrical and weaken. Florence made landfall in North Carolina on as a category one hurricane and moved slowly over the Carolinas producing torrential rainfall and devastating flooding. Many rivers across the Carolinas came close or actually broke their rainfall records. It took many weeks and in some places a month for the waters to recede and the rivers to fall below flood stages.
Hurricane Michael was the second of two major hurricanes this season. It formed in the Caribbean Sea on October 2nd, 2018 and traveled slowly through the Gulf of Mexico. Once in the Gulf of Mexico, it rapidly intensified and became a major hurricane on October 9th, 2018. Hurricane Michael reached a peak intensity of a high-end category four hurricanes with maximum sustained winds of 155 miles per hour. On October 10th, 2018, Hurricane Michael made landfall on the Florida panhandle near Mexico Beach, Florida. Michael caused widespread damage across the panhandle with a fourteen-foot storm surge that washed houses away and strong winds that destroyed buildings and foundations. Michael was the fourth strongest storm to make landfall in Florida since Hurricane Andrew in 1992 in regard to its wind speed. It was also the third strongest hurricane in regard to its central pressure with a minimum central pressure of 919 millibars to make landfall since Hurricane Camille in 1969.
Overall this Hurricane season was pretty active this year. Tropical Storm Alberto kicked the season off early on May 25th, 2018 making landfall in Florida. Seven of the fifteen named storms were subtropical at a point in their lifetime. A named storm that has characteristics of a non-tropical storm is called a sub-tropical storm. These seven storms this season all became tropical storms and three of them intensified to hurricane status. For the first time since 2008, the Atlantic saw four named storms existing in the Atlantic basin together. Florence, Helene, Isaac, and Joyce all co-existed for a period of time this season. With the 2018 Hurricane season finished, it is never too early to begin making preparations for next summer. It’s important to have a plan in place if you live in hurricane-prone areas because it only takes one storm to cause significant damage. Being prepared and tuned into your local and government weather service offices is a great way to be ready for the 2019 season! For more information on having a hurricane ready plan click here!
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© 2018 Meteorologist Shannon Scully
What is the Meaning and Importance Behind a Tropical Cyclone's Outflow? (Imagery credit: Himawari-8 Satellite Imager)
DISCUSSION: Year in and year out, millions of people all over the world bear witness to the formation of tropical cyclones in tropical ocean basin across the globe. During some of the more intense tropical cyclones which form during a given year, there are often some neat satellite imagery-based signature features which can be greatly appreciated even by the general public. One such example of an interesting feature which will often occur in association with tropical cyclones of variable intensities, but most often in association with major hurricanes (i.e., across the tropical Eastern and/or Central Pacific Ocean as well as the tropical Atlantic Ocean is upper-level outflow.
Upper-level outflow associated with a tropical cyclone is particularly interesting since it will always flow in the opposite direction from the more intense cyclonic (anticyclonic) winds which occur with tropical cyclones which form within the Northern (Southern) Hemisphere. However, the big question which many people will often inquire about in association with upper-level outflow tied to more intense tropical cyclones is why the upper-level winds from in the opposite direction of the low/mid-level wind flow regime. As is often the case with many interesting scientific conundrums in life, the answer to this question is actually very simple. And that answer is a result of a basic atmospheric dynamics principle and fundamental law of atmospheric physics. This basic atmospheric dynamic principle is the fact that above any low-pressure center is a high-pressure center and above any high-pressure center is always going to be a nearby low-pressure center. Effectively, this fundamental principle is what allows the atmosphere to always remain at or closer to a dynamically-stable state of atmospheric balance over both shorter-term and longer-term periods.
When it comes to observing upper-level outflow associate with a tropical cyclone via satellite imagery, it is often photogenic and almost mesmerizing to watch. Moreover, upper-level outflow is often found to be quite attention-grabbing despite the storm encapsulated within the symmetric outflow (or sometimes asymmetric outflow depending on the given situation at hand) being quite powerful towards the surface of the Earth. Thus, this just goes to show that even the more interesting and curious details of a larger weather event can be quite interesting to understand on a more profound level.
To learn more about this particular issue, please also visit our GWCC Kid's Corner, which can be found right here!
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© 2018 Meteorologist Jordan Rabinowitz
How Historic Was Hurricane Michael Really? (Photo Credit: The Weather Channel and the National Hurricane Center)
DISCUSSION: Earlier this month, on October 10, 2018, Hurricane Michael made landfall along the Panhandle of Florida, over the city of Mexico Beach. Michael made landfall as a strong Category 4 storm, with maximum sustained winds of 155 mph. In addition to the strong winds, Hurricane Michael’s central pressure was exceptionally low, at 919 mb. The winds, combined with storm surge as high as 12 feet in some areas, lead to devastating destruction of land and property along the path of the hurricane. Due to all of this, Hurricane Michael is already being called a historical event, but just how rare is an event like Hurricane Michael.
For starters, it is rare for a hurricane to make landfall in the continental United States as a Category 4 or greater. Since 1851 there have only been 27 hurricanes to do so, with the greatest number making landfall over Florida, as can be seen in the image above. However, despite this, since the United States began keeping a record of hurricanes there has never been a Category 4 or 5 hurricane to make landfall along the Florida panhandle. Therefore, the location that Michael made landfall by itself makes it historic.
Aside from its location, it was also the first hurricane to make landfall in the United States in the month of October as a Category 4 or higher storm since Hurricane Hazel 64 years ago. Hurricane Hazel was a Category 4 hurricane when it made landfall near the border of North Carolina and South Carolina on October 15, 1954. Its estimated maximum winds were between 130 mph and 150 mph and had storm surge that reached 18 feet along portions of North Carolina. The storm then moved northward into Canada, where it dropped 11 inches of rainfall in Toronto.
Hurricane Michael’s minimum central pressure also makes it unique. Since 1851 there have only been two storms, The Florida Keys Labor Day Storm in 1935 and Hurricane Camille in 1969, that had a lower central pressure at landfall. The Labor Day storm made landfall as a Category 5 storm with a central pressure of 892 mb in the Florida Keys. It then turned to the northeast and made a second landfall as a Category 2 storm near Cedar Key Florida. Hurricane Camille was also a Category 5 when it made landfall along the Mississippi coast with a central pressure of 900 mb. Its maximum wind speed was not recorded because the wind instruments in the path of the storm were destroyed but winds along the coast were estimated to be 200 mph. Hurricane Michael also beat Hurricane Katrina’s minimum central pressure which was 920 mb, though not by much. Katrina, which devastated New Orleans in 2005, had been a Category 5 storm with a minimum pressure of 902mb the day before landfall but at the time of landfall on Aug 29 it had weakened to a Category 3 and its minimum pressure increased.
The location, time of year, and the minimum central pressure of the Hurricane Michael for sure make it an historical event. However, these factors alone will likely not be the only reasons Hurricane Michael will live in infamy. In the following weeks, months, and years we will continue to examine the storm and likely find other factors that will add to the historic nature of this event. Even more, we do not know the economic impact the storm had, and the amount of property and loved ones lost.
Additional information about memorable hurricanes to hit the US can be found at: https://www.nhc.noaa.gov/outreach/history/
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© 2018 Meteorologist Sarah Trojniak
Inside Edge on What Helped Hurricane Michael to Rapidly Intensify Leading up to Landfall. (Imagery credit: Meteorologist Stu Ostro)
DISCUSSION: There is no question that Hurricane Michael shocked the state of Florida and the rest of the world for that matter on the morning of October 10th, 2018. It goes without saying that Hurricane Michael will undoubtedly go down in history as one of the top five most intense hurricanes to make a direct hit on the contiguous United States as far back as records go. Having said that, it is even more interesting to learn more about and why Hurricane Michael managed to intensify so quickly and so close to the official point of landfall in northeast Florida as this system did. This is complicated and yet, at the same time represents a perfect example of a classic tropical cyclone intensification scenario.
To get into the factors which went into how and why Hurricane Michael intensified as quickly and abruptly just before its landfall near Mexico Beach, Florida, there are some atmospheric and environmental fundamentals which must exist. It is imperative to establish the fact that for a hurricane to intensify and/or rapidly intensify at any point in time, there must always be sufficiently warm sea-surface temperatures in place both under and out ahead of an approaching tropical cyclone. In the case of Hurricane Michael, there was more than sufficiently warm sea-surface temperatures spread across the northeastern Gulf of Mexico out ahead of the forward approach of Hurricane Michael. Hence, the first major piece was most certainly in place for this tropical cyclone.
The second major environmental factor which is key and essential for tropical cyclone intensification is the presence of little to no vertical wind shear both surrounding the immediate location of the intensifying tropical cyclone and out ahead of the given tropical cyclone. In the case of Hurricane Michael, the main concern regarding the presence of vertical wind shear was when this system was developing both near and just to the north of the Yucatan Peninsula in eastern Mexico. However, as this storm continued to move northward with time, the issues pertaining to the presence of vertical wind shear subsided rather quickly as the storm’s inner and outer core organized rather quickly with time which limited the vertical wind shear threat and concerns thereof. Thus, the second piece of the puzzle was most certainly in place for then intensification of Hurricane Michael.
The third major piece which is important and is critical both ahead and during a period of intensification and/or rapid intensification of a tropical cyclone is to have an effective and consistent outflow channel both surrounding and out ahead of a strengthening tropical cyclone. This consistent outflow surrounding an intensifying tropical cyclone is important since this allows a tropical cyclone to vent all the excess “cloud debris” and excess heat energy which is always being released both above and surrounding the convective inner and outer portions of a developing and/or mature tropical cyclone. As shown in the animated graphic attached above, there was most certainly an effective outflow channel in place with Hurricane Michael which allowed for this outflow channel to be maintained incredibly well with Michael right up to the point of landfall.
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© 2018 Meteorologist Jordan Rabinowitz