DISCUSSION: There is no debate that the Friday morning landfall of Tropical Cyclone Fani brought about truly horrific consequences for a good portion of the eastern half of the subcontinent of India. Having said that, with most of the worst of the event having unfolded and concluded up to this point in time, is most certainly worth it and necessary to take a look back and see how this event unfolded. More specifically, it is often most interesting to evaluate how and to what extent the physical structure of a given tropical cyclone evolves during its lifetime and more specifically during its landfall and post-landfall period(s), respectively.
Through utilizing the Cooperative Institute for Meteorological Satellite Studies (CIMSS) Morphed Integrated Microwave Imagery at CIMSS (MIMIC), there are several more profound insights which can be gained from this recent and historic tropical cyclone which formed and intensified within the Bay of Bengal (i.e., to the south and east of eastern India). First off, upon analyzing the pre-landfall phase of Tropical Cyclone Fani, you can clearly see how it maintained a structurally-sound eye and eye-wall. You can determine the fact that it had a structurally-sound eye-wall by seeing how towards the beginning of the brief loop, there was a relatively consistent coverage of yellow to red-colored banding around the clear eye which indicates the presence of deeper convection surrounding the immediate center of the storm’s circulation. Thus, as you may suspect, this was around the time at which Tropical Cyclone Fani was near and around the period of peak intensity. After that time, upon a bit closer investigation, you can also see how there was a slight widening of the average diameter of the eye in the hours leading up to the landfall of Tropical Cyclone Fani. A gradual widening of an eye during the last 24 hours preceding a landfall is quite common with tropical cyclones around the world (under most environmental circumstances) and is most often an indication of a process known as an eyewall replacement cycle occurring. During this process, the common consequences to an average tropical cyclone is that there is a widening of the eyewall, a corresponding increase in the size of maximum wind speed field, and sometimes a weakening of the maximum wind speeds by at least 5 to 15% of the original maximum sustained wind speeds. Once the storm made landfall, you can then observe how the storm fully broke down in terms of its organization and that the eye collapsed quickly which is an inevitable factor when a tropical cyclone interacts with any sizable landmass. Such landmass interactions degrade the internal structure and organization of a tropical cyclone since this interaction cuts off the critical inflow of warm, moist air towards the center of the storm. Thus, this process facilitates a rapid weakening of the storm from that point forward and this is exactly what you are seeing with Tropical Cyclone Fani during the post-landfall phase of this tropical cyclone as it moved northward towards southern Bangladesh. To learn more about other tropical cyclone events and stories from around the world, be sure to click here! © 2019 Meteorologist Jordan Rabinowitz
0 Comments
Understanding the Historical Context of Tropical Cyclone Fani (Imagery credit: Himawari-8 Imager)5/3/2019 
DISCUSSION: Over the past couple of days, millions of people from around the world were witnesses to an increasingly scary situation in the context of the robust intensification and the approach of Tropical Cyclone Fani to an eventual landfall in eastern India. From a historical perspective, this was an incredibly impressive event on all accounts. First, despite the relatively commonality of tropical cyclones forming in this region of the world (i.e., across the northern and/or southern Indian Ocean), it is not all that often that the subcontinent of India or any other adjacent countries get in the path of such a powerful tropical cyclone. That being said, such events do occasionally occur and when they do, there are often substantially noticeable and lasting impacts.
In the case of Tropical Cyclone Fani, this was a large and powerful tropical cyclone which at its period of peak intensity (i.e., within the 12 to 24 hours prior to its landfall in eastern India) had maximum sustained winds of around 150 mph with gusts to around 190 mph. Thus, making it an incredibly large and dangerous tropical cyclone which was being estimated as a storm which would have the potential to forever change the lives of hundreds of millions of people as and beyond the point at which it makes landfall. To put this storm in context, the last tropical cyclone to impact the subcontinent of India was Tropical Cyclone Hudhud back in October 2014 as a severe tropical cyclone. Despite the fact that Fani was a somewhat weaker system at the time of landfall than Hudhud, Fani was a MUCH larger system with a lot more water being carried along with it. Thus, the major concern and still a major ongoing concern is the continued flooding and flash flooding threat across northern India, Bangladesh and beyond. The major rainfall production will continue even as this storm weakens and gradually gets absorbed by the larger-scale atmospheric flow across southern Asia. Having said all the above, it still goes without saying that Tropical Cyclone Fani will most definitely go down in the record books as being one of the likely top ten worst tropical storms to impact the subcontinent of India in recorded history. To learn more about other tropical cyclone events from around the world, be sure to click here! © 2019 Meteorologist Jordan Rabinowitz 
DISCUSSION: Tropical cyclone (hereafter TC) intensity continues to be a fundamental forecasting challenge and despite the multitude of data outlets at the ready, real-time analysis does not always allow for precise estimates. However, a positive that arises with many datasets is the ability to further examine the true intensity and track of a previous season’s TCs. This analysis is known as a retrospective analysis (or reanalysis) and it is exactly what is done with each TC that formed in the previous season. Recently, Hurricane Matthew (Atlantic) was reclassified as a category 5 hurricane on the Saffir-Simpson scale at landfall which made it the fourth category 5 hurricane to impact United States soil in recorded history (the previous three were the Labor Day Hurricane of 1935, Camille in 1969, and Andrew in 1992). In real time, peak wind speeds in the eyewall of Matthew were estimated to be 155 mph but the post-season reanalysis revealed that peak wind speeds were in fact closer to 160 mph. A small change such as this may seem small on paper so it does beg the question, “what is the real importance of such a small upgrade?”
To understand the previous question, one must understand the procedure and subsequent impact of retrospective analyses. For brevity, the most significant points during the reanalysis run is explained. During a real-time observation and forecast, forecasters ingest large quantities of data from several ground-based and satellite-based products in order to generate a more profound analysis of the ongoing TC. These include observations from aircraft reconnaissance, surface station-reported winds, cloud-top based satellite intensity estimates and, if close enough to land, Doppler radar velocities, among many other viable datasets. These “raw” datasets are then quality-controlled to mask out any noise or contamination in the data fields and are then passed through post-processing routines to generate the accurate analysis fields. Ultimately, all of the available products are given consideration and are consulted simultaneously for any positive or negative discrepancies compared to the estimates during real-time. In the case of hurricane Michael, the peak wind speed of 160 mph was detected using a combination of the aforementioned datasets, and this peak occurred as the storm was nearing landfall near Mexico Beach, FL. As mentioned previously, some of the data used in a reanalysis may not have been made readily available during the real-time event which further enhances the significance of a reanalysis. In short, real-time analyses of TCs can be a significant challenge for forecasters to make a precise estimate on TC track and intensity given the pressures of pushing out timely forecasts for the general public. However, going back to re-examine storms with the potential to access more data than what was made available during a real-time event allows for the forecasters to return and appropriately adjust the TC’s. As the availability and portability of weather data continues to expand, more tools and reference datasets would continue to aid forecasters in making more accurate predictions for TC track and intensity in years to come. To learn more about other interesting tropical cyclone topics and events from around the world, click here! © 2019 Meteorologist Brian Matilla 
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. To learn more about other interesting tropical cyclone topics and events from around the world, click here! © 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.
To learn more about other tropical cyclone-related topics from around the world, click here!
© 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. To learn more about other tropical cyclone-related topics from around the world, click here! © 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. To learn more about other tropical cyclone topics from around the world, click here! © 2019 Meteorologist Jordan Rabinowitz An Interesting Assessment of Hurricane Florence's Rainfall Event Via Regional Rainfall Gauges1/6/2019 
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. To learn more about other tropical cyclone events from around the world, click here! © 2019 Meteorologist Jordan Rabinowitz How Can A Tropical Storm Erase an Island from the World Map? (Credit: NASA Earth Observatory)12/9/2018  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.” To gain access to the original article in its entirety, click here! To learn more about other interesting global tropical cyclone topics, click here! © 2018 Meteorologist Jordan Rabinowitz  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! To learn more about other tropical cyclone stories from around the world, be sure to click here! © 2018 Meteorologist Shannon Scully |
Archives
May 2019
|
RSS Feed