The 29th Annual Hurricane Showdown will take place during Thanksgiving Weekend, Friday November 24th through Sunday November 26th with games played on all 3 days.This will allow us to quickly verify. All rosters will be available on our “Teams” tab for reference once verified. Please work with your Member City to ensure your players are indicated appropriately in the NAGAAA Database by First and Last Name, Date of Birth, and current rating based on the most recently approved NAGAAA player ratings questionnaire (Spring 2023).
All Players in C, D, & E Divisions MUST be NAGAAA Rated under the new ratings questions (Spring 2023). the Hurricane Showdown staff will verify player ratings based on what is in the NAGAAA Database. We will not allow anyone to play who does not have a NAGAAA rating in the database. There will be no exceptions!
Powell, M.D., and S.H. Houston, 1996: “Hurricane Andrew’s wind field at landfall in South Florida. Part II: Applications to real -time analysis and preliminary damage assessment” Wea. Forecasting, 11, pp.329-349It was an ambitious experimental program of research on hurricane modification carried out between 1962 and 1983. The proposed modification technique involved artificial stimulation of convection outside the eyewall through seeding with silver iodide. The invigorated convection, it was argued, would compete with the original eyewall, lead to the reformation of the eyewall at larger radius, and thus, through partial conservation of angular momentum, produce a decrease in the strongest winds. A warmer ocean can have intensifying effects because the warmer an ocean is, the easier it is for the liquid water to become vapor and fuel the storm’s clouds. Currently, there are six yearly lists used in rotation found here. If a particularly damaging storm occurs, the name of that storm is retired. Storms retired in 2017 include Harvey, Irma, Maria, and Nate. If there are more storms than names on the list in a given season, an auxiliary name list is used. Lastly, if a storm happens to move across basins, it keeps the original name. The only time it is renamed is in the case that it dissipates to a tropical disturbance and then reforms.The purposes of research are more varied. Onboard scientists direct the aircraft to those parts of the storm of interest, which might not be near the eye of the hurricane. Experiments might be planned to examine the outer rainbands or the hurricane’s interaction with the environment. There are several assumptions made in this chain of logic. The first is that there are too few cloud condensation nuclei (CCN) available naturally. If there aren’t, then adding more wouldn’t change things. The next assumption is that more numerous but smaller cloud drops wouldn’t coalesce into larger drops, even in the turbulent updraft of a hurricane eyewall. And lastly, it assumes that the increased burden on the updraft outweighs the increase in latent heat released when more liquid water reaches the freezing level. If less water is precipitating out, then more will be freezing. The best time to prepare is before hurricane season begins. Make a plan for you and your family about what to do if a hurricane threatens. Put together a hurricane kit. Ensure your house is up to code, and check for problems, such as overhanging branches or missing roof tiles. Check your shutters and other window and door coverings. Once the season begins, stay informed. Check the outlook every day, and if anything is threatening keep updated on the latest advisories.A network of 175 long-term, continuously operating water level stations located throughout the U.S. serving as the foundation for NOAA’s tide prediction products.While one would intuitively expect tropical cyclones to peak right at the time of maximum solar radiation (late June for the tropical Northern Hemisphere and late December for the tropical Southern Hemisphere), it takes several more weeks for the oceans to reach their warmest temperatures. The atmospheric circulation in the tropics also reaches its most pronounced (and favorable for tropical cyclones) at the same time. This time lag of the tropical ocean and atmospheric circulation is analogous to the daily cycle of surface air temperatures – they are warmest in mid-afternoon, yet the sun’s incident radiation peaks at noon.The Australian and South Pacific region (east of 90E, south of the equator) started giving women’s names to the storms for the 1964/1965 season and both men’s and women’s names for the 1974/1975 season. For the 2008/2009 season the three separate name lists of the different BoM forecast centers were consolidated into one list. Volcanic eruptions cause a transient cooling of ocean temperatures as they tend to block some of the incoming sunlight from reaching the surface. These natural eruptions tend to occur randomly and don’t exhibit any clear multi-decadal swings. There is an undeniable drama to hurricanes; their massive scale affecting the lives of thousands, the foreshadowing of impending doom, and their ponderous pace as they approach the shore. This has made them ideal plot elements in many fictional works. Below is an admittedly partial list of some novels, plays, poems, and movies which have used hurricanes as a major dramatic element.That’s a lot of assumptions, and it would have to be proven in computer models first, then in field tests, that they are valid. Otherwise, you would expend a great deal of money and effort, but not change a hurricane sufficiently.
When a tropical disturbance organizes into a tropical depression, the thunderstorms will begin to line up in spiral bands along the inflowing wind. The winds will begin to increase, and eventually the inner bands will close off into an eyewall, surrounding a central calm area known as the eye. This usually happens around the time wind speeds reach hurricane force. When the hurricane reaches its mature stage, eyewall replacement cycles may begin. Each cycle will be accompanied by fluctuations in the strength of the storm. Peak winds may diminish when a new eyewall replaces the old, but then re-strengthen as the new eyewall becomes established.
The USAF planes are the workhorses of the hurricane hunting effort. They are often deployed to a forward base, such as Antigua, and carry out most of the reconnaissance of developing waves and depressions. Their mission in these situations is to look for signs of a closed circulation and any strengthening or organizing that the storm might be showing. This information is relayed by satellite to the hurricane specialists who evaluate this information along with data from other platforms.The “right side” is in reference to the storm’s direction of movement in the Northern Hemisphere. If a hurricane is moving to the west, the right side would be to the north of the storm, if it is heading north, then the right side would be to the east of the storm. In the Southern Hemisphere, this is reversed since a tropical cyclone’s winds spiral around its center clockwise there as opposed to counterclockwise in the Northern Hemisphere. So south of the Equator the “dirty side” is the “left side” of the cyclone.Evaporation from the sea surface fuels tropical storms and hurricanes. Over relatively calm water (such as for a developing tropical depression or disturbance), in theory, an oil slick could suppress evaporation if the layer is thick enough, by not allowing contact of the water to the air. References: Neumann, C.J., B.R. Jarvinen, C.J. McAdie, and J.D. Elms (1993): Tropical Cyclones of the North Atlantic Ocean, 1871-1992, Prepared by the National Climatic Data Center, Asheville, NC, in cooperation with the NHC, Coral Gables, FL, 193pp. Hurricane forecasters estimate tropical cyclone strength from satellite using a method called the Dvorak technique. Vern Dvorak developed the scheme in the early 1970s using a pattern recognition decision tree (Dvorak 1975, 1984). Utilizing the current satellite picture of a tropical cyclone, one matches the image versus a number of possible pattern types: Curved band Pattern, Shear Pattern, Eye Pattern, Central Dense Overcast (CDO) Pattern, Embedded Center Pattern or Central Cold Cover Pattern. If infrared satellite imagery is available for Eye Patterns (generally the pattern seen for hurricanes, severe tropical cyclones and typhoons), then the scheme utilizes the difference between the temperature of the warm eye and the surrounding cold cloud tops. The larger the difference, the more intense the tropical cyclone is estimated to be.Although rarer, some East Pacific names have been retired from the list. The climatology of this basin has most hurricanes moving away from the shore, so chances are rare that these storms would adversely affect people necessitating the name be retired.But what does get interesting is flying through the hurricane’s rainbands and the eyewall, which can get a bit turbulent. The eyewall is a donut-like ring of thunderstorms that surround the calm eye. The winds within the eyewall can reach as much as 200 mph [325 km/hr] at the flight level, but you can’t feel these aboard the plane. But what makes flying through the eyewall exhilarating and at times somewhat scary, are the turbulent updrafts and downdrafts that one hits. Those flying in the plane definitely feel these wind currents (they sometimes makes us reach for the air-sickness bags). These vertical winds may reach up to 50 mph [80 km/hr] either up or down, but are actually much weaker in general than what one would encounter flying through a continental supercell thunderstorm. But once the plane gets into the calm eye of a hurricane like Andrew or Gilbert, it is a place of powerful beauty: sunshine streams into the windows of the plane from a perfect circle of blue sky directly above the plane, surrounding the plane on all sides is the blackness of the eyewall’s thunderstorms.
A rare South Atlantic storm in 2004 was post facto given the name Catarina. Another such system in 2010 was designated Anita after the fact. Starting in 2011, a name list was begun for the South Atlantic basin using mostly Brazilian designations.
The Northwest Pacific basin, similar to the Australian/Southwest Pacific basin, experiences a change in location of tropical cyclones without a total change in frequency. Pan (1981), Chan (1985), and Lander (1994) detailed that west of 160°E there were reduced numbers of tropical cyclone genesis with increased formations from 160E to the dateline during El Niño events. The opposite occurred during La Niña events. Again there is also the tendency for the tropical cyclones to also form closer to the equator during El Niño events than average.Ocean temperatures in the region where most Atlantic hurricanes form and develop have been trending upwards as the Earth has gradually warmed since the mid-19th Century (top panel, Fig. 1). In addition to trending upwards, ocean temperatures show large multi-decadal climate swings from cooler to warmer than average. This becomes clearer when the warming trend is removed (middle panel). Atlantic hurricane activity has responded to these swings in a variety of ways. For example, the number of Atlantic major hurricanes (Saffir-Simpson categories 3–5) is greater during periods of warmer than usual temperatures (bottom panel).
In the Atlantic basin, tropical cyclone names are “retired” (not to be used again for a new storm) if it is deemed to be quite noteworthy because of the damage and/or deaths it caused. This is to prevent confusion with a historically well-known cyclone and a current one in the Atlantic basin. Sometimes names are removed for other reasons, such as cultural considerations or politics. The following list gives the names that have been retired and the year of the storm in question.
Lyons, W.A., and C. S. Keen (1994): “Observations of lightning in convective supercells within tropical storms and hurricanes” Mon. Wea. Rev., 122, pp.1897-1916Chen, S.A., and W.M. Frank (1993): “A numerical study of the genesis of extratropical convective mesovortices. Part I: Evolution and dynamics” J. Atmos. Sci., 50, pp.2401-2426Hurricane Warning – Hurricane warnings are issued 36 hours in advance and are announced when hurricane force winds are expected somewhere within the specified area in association with a cyclone. This warning can remain in effect in the face of other hazards, such as flooding even if the winds drop to below hurricane force.An upper atmospheric perturbation known as the Madden-Julian Oscillation (MJO) can travel around the globe on a time-scale of weeks. As its positive phase passes over an area it can bring favorable conditions for convection, while its negative phase can suppress it. This can affect forming tropical cyclones either giving them a boost or hindering them.
Our sun has 11-year and 22-year cycles in sunspot and magnetic activity, which affects the solar wind and Earth’s magnetic field. It may also exhibit longer scale variability in its output. Along with changes in comic ray activity, this may alter Earth’s cloud cover in subtle ways and drive changes in ocean heat content.Names retired before the 2000 season come from the name lists used by the Joint Typhoon Warning Center. Since 2000, the names removed come from the name lists used by the Japan Meteorological Agency. Most of the retired names inflicted significant damage to the nations affected.
Gray, W.M., W.M. Frank, M.L. Corrin, C.A. Stokes (1976): “Weather modification by carbon dust absorption of solar energy” J. Appl. Meteor., 15, pp.355-386It would take a tremendous amount of whichever substance you choose to alter the energy balance over a wide swath of the ocean in order to have an impact on a hurricane. One would hope that this substance would eventually disperse or disintegrate and not have a terrible impact on the earth’s ecology. Knowing where to place it would also be tricky. You don’t want to heat up the wrong area of the atmosphere or you could put more energy into the cyclone. These proposals would require a great deal of precisely-timed, coordinated activity to spread the layer, while running the risk of doing more harm than good. Many computer simulations should be run before any field test were tried.
The mean annual damage from hurricanes in the US is 9.5 billion dollars, when we adjust not only for inflation but for the increase in value of real goods in average households. Hurricane damage varies greatly from year to year, depending on the number and strength of hurricanes making landfall, but there does not seem to be a long-term trend in adjusted damage over the last century.
This lack of inner core lightning is due to the relative weak nature of the eyewall thunderstorms. Because of the lack of surface heating over the ocean ocean and the “warm core” nature of the tropical cyclones, there is less buoyancy available to support the updrafts. Weaker updrafts lack the super-cooled water (e.g. water with a temperature less than 0° C or 32° F) that is crucial in charging up a thunderstorm by the interaction of ice crystals in the presence of liquid water (Black and Hallett 1986). The more common outer core lightning occurs in conjunction with the presence of convectively-active rainbands (Samsury and Orville 1994).
A post-tropical cyclone is a former tropical cyclone that no longer possesses sufficient characteristics to be considered a tropical cyclone, such as convection at its center. Post-tropical cyclones can continue producing heavy rains and high winds. Former tropical cyclones that have become fully extra-tropical, sub-tropical, or remnant lows, are three classes of post-tropical cyclones.Oftentimes, hurricane specialists become curious about disturbances in the tropics long before they form into tropical depressions and are given a tropical cyclone number. In order to alert forecasting centers that they are investigating such a disturbance and that they wish to have it tracked by the various forecast models, the specialist will attach a 9-series number to it. The first such disturbance of the year will be designated 90, the next 91, and so on until 99. After that, they restart the sequence with 90 again. The purpose of these numbers is to clarify which disturbance they are tracking as there are often more than one happening at the same time.The ocean’s primary direct response to a hurricane is a cooling of the sea surface temperature (SST). How does this occur? When the strong winds of a hurricane move over the ocean they churn-up much cooler water from below. The net result is that the SST of the ocean after storm passage can be lowered by several degrees Celsius (up to 10° Fahrenheit).
To further clarify matters, each number is accompanied by a two-letter code designating which tropical cyclone basin the disturbance is in. “AL” is used for the Atlantic basin (including the Caribbean Sea and Gulf of Mexico), “EP” for the Eastern Pacific, “CP” for Central Pacific, and “WP” for the Western Pacific.In March, 2004 a hurricane DID form in the South Atlantic Ocean and made landfall in Brazil. But this still leaves the question of why hurricanes are so rare in the South Atlantic. Though many people might speculate that the sea surface temperatures are too cold, the primary reasons that the South Atlantic Ocean gets few tropical cyclones are that the tropospheric (near surface to 200mb) vertical wind shear is much too strong and there is typically no inter-tropical convergence zone (ITCZ) over the ocean (Gray 1968). Without an ITCZ to provide synoptic vorticity and convergence (i.e. large scale spin and thunderstorm activity) as well as having strong wind shear, it becomes very difficult to nearly impossible to have genesis of tropical cyclones.
In addition to hurricane-favorable conditions such as temperature and humidity, many repeating atmospheric phenomenon contribute to causing and intensifying tropical cyclones. For example, African Easterly Waves (AEW) are winds in the lower troposphere (ocean surface to 3 miles above) that originate and travel from Africa at speeds of about 3-mph westward as a result of the African Easterly Jet. These winds are seen from April until November. About 85% of intense hurricanes and about 60% of smaller storms have their origin in African Easterly Waves. Reference: The Deadliest, Costliest, and Most Intense United States Tropical Cyclones from 1851 to 2006 (and other Frequently Requested Hurricane Facts) NOAA Technical Memorandum NWS TPC-5 April 15, 2007, Eric S. Blake, Edward N. Rappaport, Christopher W. Landsea. A rare hurricane near Hawaii in 1950 was called Hiki (Hawai’ian for Able). In 1957, three storms were detected in the Central Pacific, and the military forecast centers called them Kanoa, Della and Nina. In 1959, another hurricane threatened the islands and the Weather Bureau designated it “Dot”. The next year an official name list for tropical cyclones was drawn up for the Northeast Pacific basin. In 1978, both men’s and women’s names were utilized, and in 1979 a separate list was created for the Central Pacific (from 140°W to 180°W) using Hawaiian names.Reference: Powell, M.D., S.H. Houston, and T.A. Reinhold, 1996:”Hurricane Andrew’s Landfall in South Florida, Part I: Standardizing measurements for documentation of surface wind fields.” Wea. Forecast. v.11, p.329-349There have been proposals to tow icebergs to the Atlantic and cool sea surface temperatures, or to pump deep water to the surface. The problem with this is both the size scale and the movement of the hurricane, not to mention the track uncertainty and ecological implications. Attacking weak tropical waves or depressions before they have a chance to grow into hurricanes isn’t promising either. About 80 of these disturbances form every year in the Atlantic basin, but only about 5 become hurricanes in a typical year. There is no way to tell in advance which ones will develop. If the energy released in a tropical disturbance were only 10% of that released in a hurricane, it is still a lot of power. The hurricane police would need to dim the whole world’s lights many times a year. These official forecasts are later verified and then consolidated into a “best track” for the storm. The Best Track has a center position and maximum wind speed value for each six-hour time that represents the official NHC estimate of the location and intensity of a tropical cyclone. Values of central pressure and the radii of hurricane-force and gale-force winds may also be included as well as other significant events, such as landfall or peak intensity, especially if they occur other than the six-hourly times.
To convert this to your local time it is necessary to subtract the appropriate number of hours for the Western Hemisphere or add the correct number of hours for the Eastern Hemisphere. And don’t forget the extra hour adjustment for Daylight Savings Time or Winter Time over Standard Time for your zone.
Although Wragge’s naming practice lapsed when his Queensland weather bureau closed in 1903, forty years later the idea inspired author George R. Stewart. In his 1941 novel “Storm”, a junior meteorologist named Pacific extratropical storms after former girlfriends. The novel was widely read, especially by US Army Air Forces and Navy meteorologists during World War II. When Reid Bryson, E.B. Buxton, and Bill Plumley were assigned to a USAAF base on Saipan in 1944 they had to forecast any tropical cyclones affecting operations. They decided (à la Stewart) to name them after their wives. In 1945, the armed services publicly adopted a list of women’s names for typhoons of the western Pacific using the names of officers’ wives assigned to forward forecast centers on Guam and the Philippines. However, the Air Forces were unable to persuade the U.S. Weather Bureau (USWB) to adopt a similar practice for Atlantic hurricanes.References: Hawkins, H.F., and D.T. Rubsam (1968): “Hurricane Hilda, 1964 : II Structure and budgets of the hurricane on October 1, 1964” Mon. Wea. Rev., 104, pp.418-442
Saharan dust storms have a similar effect on the Atlantic climate as the dust blows westward in the trade-winds off the African continent and blocks sunlight from reaching the ocean surface. Saharan dust storms are strongly seasonal, but can also exhibit multi-decadal swings that can cause similar swings in Atlantic ocean temperatures.
If the storm passes through an area of high vertical wind shear or dry air the storm could be weakened. However, if it continues to pick up moisture from a warm environment, then it could become a major hurricane.Here is a list of tropical cyclones that have crossed from the Atlantic basin to the Northeast Pacific and vice versa. To be considered the same tropical cyclone an identifiable center of circulation must be tracked continuously and the cyclone must have been of at least tropical storm strength in both basins (i.e. sustained winds of at least 34 kt, or 18 m/s). This record only goes back to 1923. Before the advent of geostationary satellite pictures in the mid-1960s, the number of Northeast Pacific tropical cyclones was undercounted by a factor of 2 or 3. Thus the lack of many of these events during the 1960s and earlier is mainly due to simply missing the Northeast Pacific TCs. Well, we all found out the answer in 2005 and 2020. In those years, when they ran through the name list they then use the Greek alphabet : Alpha, Beta, Gamma, Delta, Epsilon,… etc. . In 2020, they made it to a Iota on the list. Since several Greek-letter storms that year were damaging enough to have their names retired, it was decided to scrap this scheme and instead come up with an auxiliary name list each year. The same was done for the East Pacific name lists. Emanuel, K.A. (1993): “The physics of tropical cyclogenesis over the Eastern Pacific. Tropical Cyclone Disasters J. Lighthill, Z. Zhemin, G. J. Holland, K. Emanuel (Eds.), Peking University Press, Beijing, 136-142
Recent research describes two distinct types of Atlantic climate drivers: 1) Internal variability is caused by natural processes within the atmosphere and ocean climate system. 2) External variability is caused by forces outside of the atmosphere/ocean climate system.
The Atlantic meridional overturning circulation, which transports ocean heat from the tropics to higher latitudes and can cause substantial climate swings in the Atlantic region and beyond as this circulation increases or decreases. The idea here is to spread a layer of sunlight absorbing or reflecting particles (such as micro-encapsulated soot, carbon black, or tiny reflectors) at high altitude around a hurricane. This would prevent solar radiation from reaching the surface and cooling it, while at the same time increase the temperature of the upper atmosphere. Being vertically oriented, tropical cyclones are driven by energy differences between the lower and upper layer of the troposphere. Reducing this difference should reduce the forces behind hurricane winds. Currently, SLOSH basins are being updated at an average rate of 6 basins per year. SLOSH basin updates are ultimately governed by the Interagency Coordinating Committee on Hurricanes (ICCOH). ICCOH manages hazard and post-storm analysis for the Hurricane Evacuation Studies under FEMA’s Hurricane Program. Updates are driven by a number of different factors such as: changes to a basin’s topography/bathymetry due to a hurricane event, degree of vulnerability to storm surge, availability of new data, changes to the coast, and the addition of engineered flood protection devices (e.g. levees).Hurricanes have occurred outside of the official six month season , but these dates were selected to encompass the majority of Atlantic tropical cyclone activity (over 97%). When the Weather Bureau organized its new hurricane warning network in 1935 it scheduled a special telegraph line to connect the various centers to run from June 15th through November 15th. Those remained the start and end dates of the ‘official’ season until 1964, when it was decided to end the season on November 30th, and in 1965, when the start was moved to the beginning of June. These changes made the Atlantic hurricane season six months long and easier for people to remember.
Sometimes these updates include higher grid size resolution to improve surge representation, increasing areas covered by hypothetical tracks for improved accuracy, conversion to updated vertical reference datums, and including the latest topography or bathymetric data for better representation of barrier, gaps, passes, and other local features.Please note that seats are not always available on every flight, and that there is a limit of two seats per media outlet on a given flight. NOAA maintains a lengthy list of requests to fly aboard their aircraft during hurricane missions. If a hurricane is threatening landfall, local media will be given the first opportunity to fly. Due to the dynamics of hurricanes, flight plans can and do change right up until the last minute and flights are often cancelled. All of your contact information (cell numbers, pagers, home/office numbers) is extremely helpful in alerting you to changes.
Even though the major hurricanes (the category 3, 4 and 5 storms) comprise only 21% of all US landfalling tropical cyclones, they account for 83% of all of the damage.
The “extra-tropical” in extra-tropical cyclone refers to the latitudes 35°N to 65°N (or °S). However, the term refers to cyclones that get their energy from the horizontal temperature contrasts that exist in the atmosphere. Extra-tropical cyclones are low-pressure systems generally associated with cold fronts, warm fronts, and occluded fronts. They are asymmetrical and have a cold core.
Attacking weak tropical waves or depressions before they have a chance to grow into hurricanes isn’t promising either. About 80 of these disturbances form every year in the Atlantic basin, but only about 5 become hurricanes in a typical year. There is no way to tell in advance which ones will develop. If the energy released in a tropical disturbance were only 10% of that released in a hurricane, it’s still a lot of power, so that the hurricane police would need to dim the whole world’s lights many times a year.
Willoughby, H.E., J.A. Clos, and M.G. Shoreibah (1982): “Concentric eye walls, secondary wind maxima, and the evolution of the hurricane vortex” J. Atmos. Sci., 39, pp.395-411Neumann, C.J. (1993): “Global Overview” – Chapter 1″ Global Guide to Tropical Cyclone Forecasting, WMO/TC-No. 560, Report No. TCP-31, World Meteorological Organization; Geneva, Switzerland
Human beings are used to dealing with chemically complex biological systems or artificial mechanical systems that embody a small amount (by geophysical standards) of high-grade energy. Because hurricanes are chemically simple –air and water vapor – introduction of catalysts is unpromising. The energy involved in atmospheric dynamics is primarily low-grade heat energy, but the amount of it is immense in terms of human experience.
Storm Intensity – Hurricane intensity refers to the amount of energy a hurricane is carrying with it. Hurricane intensity and size are not closely related.
For a couple decades NOAA and its predecessor tried to weaken hurricanes by dropping silver iodide – a substance that serves as an effective ice nuclei – into the rainbands of the storms. During the STORMFURY years, scientists seeded clouds in Hurricanes Esther (1961), Beulah (1963), Debbie (1969), and Ginger (1971). The experiments took place over the open Atlantic far from land. The STORMFURY seeding targeted convective clouds just outside the hurricane’s eyewall in an attempt to form a new ring of clouds that, hopefully, would compete with the natural circulation of the storm and weaken it. The idea was that the silver iodide would enhance the thunderstorms of a rainband by causing the supercooled water to freeze, thus liberating the latent heat of fusion and helping a rainband to grow at the expense of the eyewall. With a weakened convergence to the eyewall, the strong inner core winds would also weaken quite a bit. For cloud seeding to be successful, the clouds must contain sufficient supercooled water (water that has remained liquid at temperatures below the freezing point, 0°C/32°F). Neat idea, but in the end it had a fatal flaw. Observations made in the 1980s showed that most hurricanes don’t have enough supercooled water for STORMFURY seeding to work – the buoyancy in hurricane convection is fairly small and the updrafts correspondingly small compared to the type one would observe in mid-latitude continental super or multicells.
References: Graham, N. E., and T. P. Barnett, 1987: Sea surface temperature, surface wind divergence, and convection over tropical oceans. Science, No.238, pp. 657-659.References: Weatherford, C. and W.M. Gray (1988): “Typhoon structure as revealed by aircraft reconnaissance. Part II: Structural variability” Mon. Wea. Rev., 116, pp.1044-1056The Southwest Indian and Australian/Southeast Indian basins have very similar annual cycles with tropical cyclones beginning in late October/early November, reaching a peak in activity from mid-January to early May. The Australian/Southeast Indian basin February lull in activity is a bit more pronounced than the Southwest Indian basin’s lull.
In the Atlantic basin, tropical cyclone names are “retired” (not to be used again for a new storm) if it is deemed to be quite noteworthy because of the damage and/or deaths it caused. This is to prevent confusion with a historically well-known cyclone with a current one in the Atlantic basin. Sometimes names are removed for other reasons, such as cultural considerations or politics.
For much of history, tropical cyclones were only given designations post facto. After they had come ashore and done much destruction, they would be commemorated by being named either for the Saint’s feast day they happened on (such as the San Felipe hurricanes in 1876 & 1928) or by some characteristic (the Salty hurricane 1810, the Yankee hurricane 1935).
Fitzpatrick, P.J., J.A. Knaff, C.W. Landsea, and S.V. Finley (1995): “A systematic bias in the Aviation model’s forecast of the Atlantic tropical upper tropospheric trough: Implications for tropical cyclone forecasting” Wea. Forecasting, 10, pp.433-446
Now for a more rigorous scientific explanation of why this would not be an effective hurricane modification technique. The main difficulty with using explosives to modify hurricanes is the amount of energy required. A fully developed hurricane can release heat energy at a rate of 5 to 20×10 watts and converts less than 10% of the heat into the mechanical energy of the wind. The heat release is equivalent to a 10-megaton nuclear bomb exploding every 20 minutes. According to the 1993 World Almanac, the entire human race used energy at a rate of 10 watts in 1990, a rate less than 20% of the power of a hurricane.
Figure 1 shows SSTs ranging between 25-27°C (77-81°F) several days after the passage of Hurricane Georges in 1998. As Figure 1 illustrates, Georges’ post-storm ‘cold wake’ along and to the right of the superimposed track is 3-5°C (6-9°F) cooler than the undisturbed SST to the west and south (i.e. red/orange regions are ~30°’C [86°’F]). The magnitude and distribution of the cooling pattern shown in this illustration is fairly typical for a post-storm SST analysis.TC tornadoes are often spawned by unusually small storm cells that may not appear particularly dangerous on weather radars, especially if the cells are located more than about 60 miles from the radar. In addition, these small storms often tend to produce little or no lightning or thunder, and may not look very threatening visually to the average person. Furthermore, the tornadoes are often obscured by rain, and the storm cells spawning them may move rapidly, leaving little time to take evasive action once the threat has been perceived. (McCaul et al. 1996, Spratt et al. 1997).There is no debate that hurricane activity is strongly linked to short-term climate swings that last for approximately a year (ENSO) and for tens of years (known as “multi-decadal variability”), but there is an ongoing scientific debate about longer-term (30+ years) climate trends: how much is due to natural phenomena, how much is due to human activities, and how they affect tropical cyclone activity.
Four hurricanes occurred simultaneously on two occasions. The first occasion was August 22, 1893, and one of these eventually killed 1,000- 2,000 people in Georgia and South Carolina. The second occurrence was September 25, 1998, when Georges, Ivan, Jeanne and Karl persisted into September 27, 1998 as hurricanes. Georges ended up taking the lives of thousands in Haiti. In 1971 from September 10 to 12, there were five tropical cyclones at the same time; however, while most of these ultimately achieved hurricane intensity, there were never more than two hurricanes at any one time.
Bess 1974 was retired after the season and replaced with Bonnie. In 1979, new name lists featuring both sexes were introduced and Bess was added back. In 1982, Bess was again retired and replaced with Brenda.The first use of a proper name for a tropical cyclone was by Clement Wragge, an Australian forecaster late in the 19th century. He first designated tropical cyclones by the letters of the Greek alphabet, then started using South Sea Island girls’ names. When the newly constituted Australian national government failed to create a federal weather bureau and appoint him director, Wragge began naming cyclones “after political figures whom he disliked. By properly naming a hurricane, the weatherman could publicly describe a politician (who perhaps was not too generous with weather-bureau appropriations) as ‘causing great distress’ or ‘wandering aimlessly about the Pacific.’ (Dunn and Miller 1960)
Central Dense Overcast (CDO) – This is the cirrus cloud shield that results from the thunderstorms in the eyewall of a tropical cyclone and its rainbands. Before the tropical cyclone reaches hurricane strength (33 m/s, 64 kts, 74mph), typically the CDO is uniformly showing the cold cloud tops of the cirrus with no eye apparent. Once the storm reaches the hurricane strength threshold, usually an eye can be seen in either the infrared or visible channels of the satellites. Tropical cyclones that have nearly circular CDO’s are indicative of favorable, low vertical shear environments. This table summarizes the occurrence of the last hurricane and major hurricane to directly hit the most populated coastal communities from Brownsville, Texas to Eastport, Maine. There are many illustrative examples of the uncertainty of when a hurricane might strike a given locality. After nearly 70 years without a direct hit, Pensacola, Florida was hit directly by Hurricane Erin in 1995 and major Hurricane Ivan in 2004 within 10 years. Miami, which expects a major hurricane every nine years, on average, has been struck only once since 1950 (in 1992). Tampa has not experienced a major hurricane since 1921. The Region IV Naming Committee has a rather large file folder of nominated names that have already been submitted. The next time the need arises and it’s a storm affecting mainly the United States, the Committee will be casting about for a replacement tropical cyclone name. They will take out this file to make a selection. But as we say, it’s pure chance from there.
Florida is no stranger to significant TC tornado activity. Among the larger outbreaks in recent Florida history are those produced by Agnes in 1972 (Hagemeyer 1997; Hagemeyer and Spratt 2002), Opal in 1995 (Sharp et al., 1997), and Charley, Frances and Ivan in 2004. Florida also gets many tornadoes from subtropical storms or TCs having hybrid characteristics, such as Josephine in 1996.
The previous record was during Hurricane Beulah, which spawned a reported 115 tornadoes in southeast Texas during the first several days after its landfall in September 1967 (Orton 1970). Frances of 2004 is close behind in third place, with 106 tornadoes, and Rita of 2005 is in fourth place with 92.References: Molinari, J., P.K. Moore, V.P. Idone, R.W. Henderson, and A.B. Saljoughy (1994): “Cloud-to-ground lightning in Hurricane Andrew” J. Geophys. Res., pp.16665-16676
Examples of natural internal forces are oceanic oscillations such as ENSO, meridional overturning circulation, and Saharan dust storms that blow mineral dust over the tropical Atlantic. The effects of the El Nino/Southern Oscillation are discussed in another section in detail.
The climatic fluctuation in the Pacific Ocean known as the El Niño-Southern Oscillation (ENSO) can affect Atlantic tropical cyclone development by increasing or decreasing (depending on ENSO phase) the vertical wind shear over the western side of the basin.
The primary purpose of reconnaissance is to track the center of circulation, these are the co-ordinates that the National Hurricane Center issues, and to measure the maximum winds. But the crews are also evaluating the storm’s size, structure, and development and this information is also relayed to hurricane specialists via satellite link. Most of this data, which is critical in determining the hurricane’s threat, cannot be obtained from satellite.A few Central Pacific names have been retired from their list. Most of them were removed for inflicting damage or adversely affecting the Hawaiian Islands. However, some have moved into the western Pacific to cause destructions, prompting their retirement.
Reference: Willoughby, H.E., D.P. Jorgensen, R.A. Black, and S.L. Rosenthal (1985): “Project STORMFURY: A scientific chronicle 1962-1983” Bull. Amer. Meteor. Soc., 66, cover and pp.505-514
The Australian/Southwest Pacific shows a pronounced shift back and forth of tropical cyclone activity with fewer tropical cyclones between 145° and 165°E and more from 165°E eastward across the South Pacific during El Niño (warm ENSO) events. There is also a smaller tendency to have the tropical cyclones originate a bit closer to the equator. The opposite would be true in La Niña (cold ENSO) events. See papers by Nicholls (1979), Revell and Goulter (1986), Dong (1988), and Nicholls (1992). The western portion of the Northeast Pacific basin (140°W to the dateline) has been suggested to experience more tropical cyclone genesis during the El Niño year and more tropical cyclones tracking into the sub-region in the year following an El Niño (Schroeder and Yu 1995), but this has not been completely documented yet. It was hypothesized to absorb sunlight and transfer heat such as black carbon, but it has not been carried out in real life. Additionally, it would likely have negative environmental and ecological consequences, and if added in the wrong place, it could even intensify the storm. Now add in the uncertainty in the track, which is currently 100 miles (160 km) at 24 hours and you have to increase your cool patch by 24,000 sq mi (38,000 sq km). For the iceberg towing method you would have to increase your lead time even more (and hence the uncertainty and area cooled) or risk your fleet of tugboats getting caught by the storm.
Maybe the time will come when men and women can travel at nearly the speed of light to the stars, and we will then have enough energy for brute-force intervention in hurricane dynamics. Tropical cyclones tend to be symmetrical. This means the winds should be the same in all quadrants at a given distance from the center. However, most hurricanes are moving, and the storm’s motion will be added to or subtracted from those winds creating an asymmetric structure. The side where the motion is added to the winds is called the “dirty side” as the weather is rougher and more dangerous there. Landsea, C.W., G.A. Vecchi, L. Bengtsson, and T. R. Knutson, 2010: Impact of Duration Thresholds on Atlantic Tropical Cyclone Counts. Journal of Climate, 23(10), 2508-2519. The Northwest Pacific basin has tropical cyclones occurring all year round regularly. There is no official definition of typhoon season for this reason. There is a distinct minimum in February and the first half of March, and the main season goes from July to November with a peak in late August/early September. There are a number of different seasonal forecasts currently being issued for various basins. Some of these are fairly new, while the oldest and most well known (Prof. Bill Gray’s forecast from Colorado State[CSU]) has been issued for almost four decades. Over the last twenty years, seasonal forescasts have been issued by the National Oceanic and Atmospheric Administration (NOAA), and Tropical Storm Risk (TSR).
Storm Track – A storm track is a representation of a tropical cyclone’s predicted path, location, and intensity over its lifetime. The best track contains the cyclone’s latitude, longitude, maximum sustained winds, and minimum sea level pressure at 6-hour intervals.
Bender, M.A., R.J. Ross, R.E. Tuleya, and Y. Kurihara (1993): “Improvements in tropical cyclone track and intensity forecasts using the GFDL initialization system” Mon. Wea. Rev., 121, pp.2046-2061Typically, for someone visiting the tropics during June through November, the chance to experience (or even be threatened by) a hurricane is very small.
Some people have proposed seeding the inflow layer of a hurricane with granules of some hygroscopic substance. The hope is that these granules will help form tiny cloud droplets, many more than would form naturally. This would tend to ‘lock up’ the moisture in small droplets, rather than allowing the formation of large drops, which tend to fall out as rainfall. This would cause a weight burden on the inflow, and reduce the hurricane’s winds.
The eastern portion of the Northeast Pacific, the Southwest Indian, the Southeast Indian/Australian, and the North Indian basins have either shown little or a conflicting ENSO relationship and/or have not been looked at yet in sufficient detail.P-Surge is available whenever a hurricane watch or warning is in effect. It is posted on the NHC webpage within approximately 30 minutes after the advisory release time.
Over the past 100 years and longer, the Atlantic hurricane environment has displayed climate swings known as “multi-decadal variability”, and hurricane activity has followed these swings. For example, in the 1940s through 1960s, ocean temperatures were warmer and hurricane seasons were more active than usual. This situation reversed during the 1970s and 1980s, which was a period of cooler ocean temperature and quieter than usual hurricane seasons. Since around the mid-1990s, we’ve been in another period of warmer than usual ocean temperatures and heightened hurricane activity.
NHC and CPHC issue an official forecast, every six hours, of the center position, maximum one-minute surface (10 meter [33 ft] elevation) wind speed (intensity), and radii of the 34 knot (39 mph,63 kph), 50 knot (58 mph,92 kph), and 64 knot (74 mph,117 kph) wind speeds in four quadrants (northeast, southeast, southwest, and northwest) surrounding the cyclone.
Holland, G.J. (1993): “Ready Reckoner” – Chapter 9, Global Guide to Tropical Cyclone Forecasting, WMO/TC-No. 560, Report No. TCP-31, World Meteorological Organization; Geneva, Switzerland
Weatherwise prints annual summaries of both the Atlantic and Northeast Pacific basins which are less technical than the Monthly Weather Review articles, but come out months earlier.
Thankfully in this case “very rare” does not mean “once in a lifetime”. Recently, scientists in AOML’s Hurricane Research Division (HRD) were able to get a better idea of how much SST cooling occurs directly under a hurricane by looking at many storms over a 28 year period. By combining these rare events, HRD scientists put together a “composite average” of ocean cooling directly under the storm.
If you’re wondering, “what is UTC time?”, or “what is GMT time?”, or “What is Z time?”, the answer is they are time schemes. Universal Time Coordinated (UTC) used to be Greenwich Mean Time and Zulu Time (Z). This is the time at the Prime Meridian given in hours and minutes on a 24 hour clock. Most satellite pictures will give the time code next to the time taken with a UTC, GMT, or Z, but they are the same time zone. The conversion table for local times can be found below.
A cyclone retains its ATCF code designation as long as it remains a distinct tropical vortex. Even if it becomes a named tropical storm or hurricane the software will still track it by its ATCF code.Hurricane Awareness week runs from May 25th through May 31st and is a great time to get your hurricane kit and plans up to date. The Atlantic hurricane season is June 1st to November 30th. In the East Pacific, it runs from May 15th to November 30th. For more information: When is Hurricane Season?
If you measure the total kinetic energy instead, it comes out to about 1.5 x 10 watts per day, or ½ of the world-wide electrical generating capacity. It would seem that although wind energy seems to be the most obvious energetic process, it is actually the latent release of heat that feeds a hurricane’s momentum.
The Northeast Pacific basin has a broader peak with activity beginning in late May or early June and going until late October or early November with a peak in storminess in late August/early September. The National Hurricane Center’s official dates for this basin are from May 15th to November 30th.Surprisingly, not much lightning occurs in the inner core (within about 100 km or 60 mi) of the tropical cyclone center. Only around a dozen or less cloud-to-ground strikes per hour occur around the eyewall of the storm, in strong contrast to an overland mid-latitude mesoscale convective complex which may be observed to have lightning flash rates of greater than 1000 per hour maintained for several hours.