 DISCUSSION: On June 25, the National Hurricane Center (NHC) issued the first advisory of the 2019 Eastern Pacific Hurricane season when an area of low pressure and thunderstorms officially strengthened into a Tropical Depression. The Eastern Pacific hurricane season starts on June 1, the same date as the Atlantic Hurricane season also begins. The tropical depression which at the time was called One-E is the first tropical storm of the season in the Pacific Ocean. One-E began as a low-pressure system off the southwestern coast of Mexico when the NHC first took notice of it on June 19. One-E began to move out toward open ocean westward and on the 25th developed a defined center of circulation with sustained winds at 30 nautical miles per hour (knots) or 35 miles per hour.
One-E officially became Alvin as it strengthened into a Tropical Storm on the 26th at the sustained windspeed of 35 knots. Alvin, according to the NHC, is the third latest date of the development of the first storm in the Pacific Ocean basin since 1966. Alvin made a westerly track as it increased in intensity with maximum sustained winds at about 55 knots. Alvin was the strongest during the afternoon of the 27th before weakening gradually as it moved westward into some of the more colder waters of the Pacific and was not be able to sustain energy for development and dissipate. Tropical storms generally weaken if the sea-surface temperature is at 80 degrees Fahrenheit or below, as there is less energy available for usage as temperature decreases. 80 degrees Fahrenheit is vital for tropical cyclogenesis (the creation and evolution of tropical cyclones) as warmer water is able to evaporate quickly and the water vapor rises up and cools down which releases the latent heat (the heat needed to convert liquid to gas or vapor) which is the main engine of the storm as it condenses. In addition, 80 degrees Fahrenheit is vital for this process as deep convection is not as possible at lower temperatures which is vital as deep convection is when the temperature of an imaginary parcel of air is warmer than the surrounding up to and above 500 millibars. Deep convection is usually affiliated especially with tropical cyclones due to the fact that the amount of energy that is released and absorbed in the storms is crucial in the thunderstorms and evaporation needed to sustain the cyclone. Alvin officially became dissipated on the morning of 29th as it became a remnant low. A remnant low is a low pressure system which involves the remains of the tropical storms and hurricanes. Alvin was never a concern to hit land due to the westward track it was taking. However, we at the Global Weather and Climate Center would like to remind you to be prepared this hurricane season by listening to warnings issued by the National Weather Service as well as to have emergency food and water for about fourteen days, blankets, batteries, flashlights, sandbags and boards for windows ready if a hurricane or tropical storm is expected to hit your area and you cannot evacuate. To learn more about tropical cyclones click here! ©2019 Meteorologist JP Kalb
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 DISCUSSION: The Atlantic hurricane season officially runs between 1 June and 30 November. Although, the past five years have seen at least one named system before 1 June including this year (Subtropical Storm Andrea). In general, relatively few storms form in the early part of the season (or before the start of the season) compared to later in the season (~September). Between 1851 and 2015, there have been 112 tropical storms (maximum sustained winds 34–64 kt) and 37 hurricanes (winds >64 kt) in May–June in the Atlantic compared to 578 tropical storms and 398 hurricanes in September. The source of energy for tropical cyclones is the evaporation of water from the ocean, and warmer water provides more energy for evaporation. In addition, water has an enormous heat capacity, so it takes a long time for water to warm up. Hence, the largest reason why there are usually relatively few storms early in the season is because the water has not had a chance to warm up yet where tropical cyclones typically form.
If a storm does form early in the season, an important question to ask is where in the basin is it most likely to form. Water tends to warm faster in the western part of the tropical Atlantic, so early season storms tend to form in the Gulf of Mexico, in the Western Caribbean, or near the east coast of the U.S. The graphic above shows the origin point (red dots) and tracks of all storms that have formed between 1 and 10 June during 1851–2015. All the storms in the Atlantic basin originated in the western part of the basin. The hurricane season in the east Pacific begins earlier (15 May) than that in the Atlantic, so there is also a cluster of storm formation in the East Pacific. The bottom line is that early storm formation in the Atlantic basin tends to occur where impacts on land are relatively likely. Finally, another important question to ask is whether there is any correlation between early season and later season activity. In other words, can storm activity in May–June be used as a predictive tool for activity during the peak of the hurricane season? Unfortunately, there is very little correlation between activity in different parts of the hurricane season. Conditions could be conducive to storm formation for an extended portion of the hurricane season, or they could be especially active for a month or so and be especially hostile to storm formation the next month; it varies from season to season. Despite usually fewer storm formations in the early part of the hurricane season, it is important to always be prepared if you live in a hurricane-prone region, especially considering early season storm formations tend to occur close to land in the western part of the basin. Remember it only takes one storm to be catastrophic. To learn more about tropical cyclones click here! ©2019 Meteorologist Dr. Ken Leppert II  GOES-16 true color satellite imagery showing Hurricane Florence's landfall near Wrightsville Beach, North Carolina on September 14, 2018. The National Hurricane Center reported Florence had sustained winds of 90 mph at landfall and was moving slowly westward at 6 mph. With the recent start of hurricane season and an active 2018 season, names like Florence and Michael come to mind. Katrina (2005), Maria (2017) - two of the top five deadliest hurricanes in U.S. history. But, do hurricane names affect how you prepare and evacuate?
The World Meteorological Organization (WMO) generates and maintains the list of hurricane names- a list of male and female names that are used on a six-year rotation. These names help to identify individual hurricanes (especially when there are multiple occurrences at once) and be able to communicate a message of safety more effectively. Here are the list of Atlantic hurricane names for 2019: Andrea, Barry, Chantal, Dorian, Erin, Fernand, Gabrielle, Humberto, Imelda, Jerry, Karen, Lorenzo, Melissa, Nestor, Olga, Pablo, Rebekah, Sebastien, Tanya, Van, Wendy. The only time hurricane names are not reused is when a storm is deadly or costly enough that its name would be inappropriate to use again. However, this naming convention may have also played into gender stereotypes. Social scientists have come to believe that feminine-named hurricanes have led to more deaths due to underestimating their risk and perceiving them as less dangerous. Certain names may play into corresponding societal roles and expectations of that sex. Male-sounding names are thought to be perceived as “intense” and “strong”. A study by the University of Illinois found that over 6 decades of hurricanes, female hurricane names had the highest death rates – as much as 3x for strong hurricanes. (There seemed to be little effect on femininity or masculinity of milder storms). For example, when asked if fictional hurricane “Alexander” or “Alexandra”, it was found that Alexander was deemed the “riskier” storm. Hurricanes did indeed have female-only names up until the late 1970’s due to their unpredictable nature, but was deemed a sexist practice. Opponents of the study say there are other factors that determine whether people are likely to evacuate: prior evacuations, having children and/or pets, and perceived structure of your home. Regardless, these findings may have important implications in the future about how storm preparedness is conveyed, especially with warming-based impacts. To learn more about tropical cyclones and other social science topics, click here! ©2019 Meteorologist Sharon Sullivan  The Atlantic hurricane season starts on June 1stof every year. Sometimes we can see storms before that date, or after that date – but subtropical storm Andrea was the first named storm of the 2019 season, and it came 11 days early!
Andrea formed just southwest of Bermuda on May 20th, 2019. The National Hurricane Center (NHC) put out their first warning of the storm and said that it would never reach above 73 miles per hours sustained winds. The storm continued on its track for some time, but never developed into anything more than a storm. Two days after the NHC put out their forecast, the storm dissipated and turned into a tropical depression with sustained winds that were less than 39 mph. Why didn’t Andrea form into a major storm? The most straightforward reason is that it formed well before the hurricane season started, which means that some of the “ingredients” for hurricane development weren’t present. The “ingredients” needed for a hurricane to form include a combination of the following conditions. First, we need a spot of convection off the equator. Convection can be explained by storms that produce severe weather, like heavy rain and thunderstorms.This is because if we want a storm to form, we need some sort of rotation, which comes from the Coriolis force. The Coriolis force doesn’t have any effect on storms (or weather) when it is isolated close to the equator the equator. This means that most storms form around 15 degrees’ latitude. When examining this condition in the context of Andrea, the the first ingredient is missing because she was located at 28 – 33 degrees North of the equator. The second ingredient necessary for a major storm to form is warm sea surface temperatures. The ideal temperature is about 26 degrees C. This allows the storm to use the warm waters and turn it into energy to intensify the storm. When looking at a sea surface temperature (SST) map of the ocean for Andrea, we can see that it formed in an area where the SST’s were around 27 degrees, and it quickly moved into colder water, which preventedt the storm from becoming stronger. Third, th next element that is required for a major storm is relatively low wind shear. This means you want a little amount of wind shear in the area – too much will destroy the storm, not enough and the storm won’t form. When Andrea moved closer to Bermuda the stronger wind shear, the storm started to “crumble” or fall apart. It became asymmetric and ruined the formation of the storm. One other thing you would need is a moist environment. If there isn’t a lot of water vapor in the environment, then it is really hard for astorm to form. If the storm moves into an area where the environment is really dry, the storm will likely fall apart and weaken. In this case Andrea moved into a region of dryer air. Overall the weather was just not ready to form a storm this early in the season, so Andrea ended up weakening. But now, we look forward to the start of the hurricane season! To learn more about other tropical cyclone events and stories from around the world, be sure to click here! © 2019 Weather Forecaster Allison Finch 
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 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 |
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