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Hurricanes This chapter discusses: 1.Tropical cyclone and hurricane development, structure, and movement 2.Hurricane damages, warning systems, and naming.

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Presentation on theme: "Hurricanes This chapter discusses: 1.Tropical cyclone and hurricane development, structure, and movement 2.Hurricane damages, warning systems, and naming."— Presentation transcript:

1 Hurricanes This chapter discusses: 1.Tropical cyclone and hurricane development, structure, and movement 2.Hurricane damages, warning systems, and naming conventions

2 Tropical Weather & Waves Tropical winds typically blow from the east, and when they encounter a slow moving trough of low pressure, called a tropical wave, the winds initially converge and lift to produce showers and thunderstorms.Tropical winds typically blow from the east, and when they encounter a slow moving trough of low pressure, called a tropical wave, the winds initially converge and lift to produce showers and thunderstorms. In the tropics, since pressure gradient are so weak, streamlines are used to depict the easterly (tropical) wavesIn the tropics, since pressure gradient are so weak, streamlines are used to depict the easterly (tropical) waves Rain showers are located behind the wave.Rain showers are located behind the wave.

3 Structures and Sizes of Hurricanes Tropical cyclone (TC) is the international name for hurricane. TC typically forms from an organized mass of storms initially starting out as a tropical wave. The central area of broken clouds is called the eye, which is surrounded by an eye wall cloud and spiral rain bands, with a total diameter nearing 500 kilometers. Hurricanes can come in many sizes but general are on the order of the meso-alpha scale. Typhoon Tip (1979) was the largest storms with gale force winds (39 mph) that extended out for 675 miles (1087 km) in radius in the Northwest Pacific on 12 October, 1979. The smallest storm was Tropical Cyclone Tracy with gale force winds that only extended 30 miles (48 km) radius when it struck Darwin, Australia, on December 24, 1974. Courtesy of the NWS

4 Hurricane Vertical Wind Profile The low pressure core of the hurricane is surrounded by several thunderstorms, each with updraft and downdraft cycles.The low pressure core of the hurricane is surrounded by several thunderstorms, each with updraft and downdraft cycles. The wind and moisture cycle is repeated as:The wind and moisture cycle is repeated as: - surface moist air converges in a counterclockwise (in the northern hemisphere) pattern at the eye; - rises to create high pressure aloft, condenses, precipitates, dries, diverges outward in a clockwise pattern, sinks, and warms. H L L H

5 3-D Radar Image and Horizontal Wind Profile of Hurricane Several key features of a hurricane are shown in this radar composite image, including overshooting clouds, the area of strongest echoes (heaviest rain), and the eyewall.Several key features of a hurricane are shown in this radar composite image, including overshooting clouds, the area of strongest echoes (heaviest rain), and the eyewall. Cloud tops within the eyewall can reach 16km (52,000 ft).Cloud tops within the eyewall can reach 16km (52,000 ft). Notice the cyclonic wind motion around a hurricane and the highest winds are locate within the eyewall.Notice the cyclonic wind motion around a hurricane and the highest winds are locate within the eyewall.

6 Ingredients Needed for Hurricane Formation Surface Ocean Temperature > 26.5 °C (80 °F) Depth of the warm water > 200 m (600 ft) Forms between 5°- 20° (Coriolis effect is needed) Surface winds convergence (ITCZ) Rising motion (trade wind inversion = bad) Weak upper level wind (high pressure aloft) During El Nino Events, upper-level winds over the Atlantic ocean are stronger.

7 Organized Convection Theory This theory explains that hurricane formation requires cold air above an organized mass of thunderstorms, where the release of latent heat warms the upper troposphere, creating high pressure aloft, which pushes air outward and causes a low to deepen at the surface.This theory explains that hurricane formation requires cold air above an organized mass of thunderstorms, where the release of latent heat warms the upper troposphere, creating high pressure aloft, which pushes air outward and causes a low to deepen at the surface. Air moving toward this low intensifies the cycle and the low pressure will deepen.Air moving toward this low intensifies the cycle and the low pressure will deepen. The stronger winds will generate rougher seas which increase surface friction.The stronger winds will generate rougher seas which increase surface friction. The increase in friction causes the wind to converge and ascend around the center of the storm.The increase in friction causes the wind to converge and ascend around the center of the storm. This set of actions eventually forms a hurricane and is considered a feedback mechanism.This set of actions eventually forms a hurricane and is considered a feedback mechanism.

8 Hurricane development process has been proposed similar to a heat engine cycle, fueled by warm moist input air and the release of heat when it converts to cool dry air.Hurricane development process has been proposed similar to a heat engine cycle, fueled by warm moist input air and the release of heat when it converts to cool dry air. Hurricane is taken heat energy at the surface and transforming it into kinetic energy.Hurricane is taken heat energy at the surface and transforming it into kinetic energy. Differences in the input and output temperatures determine the amount of work on the ocean and winds that is performed.Differences in the input and output temperatures determine the amount of work on the ocean and winds that is performed. The greater the difference, the stronger the tropical system.The greater the difference, the stronger the tropical system. Hence, the warmer the ocean surface, the lower the minimum pressure, the stronger the wind speed.Hence, the warmer the ocean surface, the lower the minimum pressure, the stronger the wind speed. Cold (Tropopause) Warm and Moist (Sea Surface) Temperature Difference

9 Hurricane Stages of Development tropical disturbance (tropical wave) – a semi-organized mass of thunderstorms generally with a cyclonic wind shift; wind speed < 20 knots (< 23 mph). tropical depression – an organized mass of thunderstorms with a weak low-level cyclonic circulation; wind speed ranges from 20 - 34 knots (23 - 39 mph). tropical storm – a more organized system of thunderstorms with cyclonic low-level winds; wind speed ranges from 35 - 64 knots (40 - 74 mph). hurricane - A well developed cyclonic system with winds exceeding 64 knots (> 74 mph).

10 Hurricanes vs. Extratropical Cyclones Extratropical Cyclones (ETC) are cold core lows.Extratropical Cyclones (ETC) are cold core lows. Intensify with heightIntensify with height Hurricanes (TC) are warm core lows.Hurricanes (TC) are warm core lows. Weaken with heightWeaken with height Center of the storm:Center of the storm: ETC – rising motionETC – rising motion TC – sinking motionTC – sinking motion IsobarsIsobars ETC – not as circularETC – not as circular TC – circular and tighterTC – circular and tighter

11 Hurricane Movement Global patterns of tropical cyclone formation and movement have been recorded on this figure, which notes regional names for these systems.Global patterns of tropical cyclone formation and movement have been recorded on this figure, which notes regional names for these systems. Travel speeds for the hurricane my range from 10 to 50 knots, but they may also stall over a region and cause destructive flooding.Travel speeds for the hurricane my range from 10 to 50 knots, but they may also stall over a region and cause destructive flooding.

12 Erratic Paths of Hurricanes Historical charts of hurricane location may reveal erratic, and hard to predict, patterns of movement.Historical charts of hurricane location may reveal erratic, and hard to predict, patterns of movement. As this figure shows, hurricanes may occasionally double back.As this figure shows, hurricanes may occasionally double back. Usually, once a tropical system enters into the middle latitudes, it turns to the northeast and increase in the system s speed. Further, when removed from the ocean and without a moisture source to supply energy, they may still continue an inland journey.Further, when removed from the ocean and without a moisture source to supply energy, they may still continue an inland journey. In the North Atlantic, on average 3 storms per year move inland and bring damaging winds and rain.In the North Atlantic, on average 3 storms per year move inland and bring damaging winds and rain.

13 North Atlantic Hurricanes Composite infrared imagery of Hurricane Georges reveals the pattern of a seasonal threat for Central and North America coastlines.Composite infrared imagery of Hurricane Georges reveals the pattern of a seasonal threat for Central and North America coastlines. Tropical cyclones at the same latitude survive longer in the Atlantic than Pacific Ocean because of warmer Atlantic Ocean waters.Tropical cyclones at the same latitude survive longer in the Atlantic than Pacific Ocean because of warmer Atlantic Ocean waters.

14 Annual average of tropical systems developing in the Atlantic basin and the numbers of those storms turning into hurricanes.

15 Climatological Areas of Origin and Typical Hurricane Tracks by Month Over the Atlantic Ocean Basin

16 The average cumulative number of Atlantic and Eastern Pacific systems Eastern Pacific Basin tends to form more named systems, hurricanes, and more intense tropical storms. Most Eastern Pacific systems tend to move out to sea and have no adverse effect on society with the exception of rip currents along the coast.

17 Australian Hurricanes Image credit: Navy Research Lab Cyclone Monica at peak intensity at 0130 GMT April 24, 2006, the strongest storm in 2006 Australia TC season-180 mph sustained winds with gusts of 215 mph, and an estimated central SLP of 879 mb pressure. Notice the clockwise rotation of tropical cyclone Monica. Southern hemisphere low pressure systems spin clockwise. Image credit: Navy Research Lab

18 The Brazilian hurricane on March 26, 2004 was the first officially recorded tropical system in the south Atlantic. The surface winds were estimated about 65 knots (~75 mph). The South Atlantic is generally not a favorable environment where tropical cyclones can form where the water temperatures are generally too cool and the vertical wind shear too strong. It was unofficially named Catarina by the weather community. Brazilian Unnamed Hurricane

19 Societal Impacts During 2004 and 2005, 8 hurricanes made landfall over Florida and Gulf Coast states. Hurricane Ivan made landfall on 15 September 2004 with winds of 121 mph and a central pressure of 945 mb. The sea level along the Alabama coast rose to 16 ft above normal causing property damage over 14 billions.

20 Hurricane Damage & Warning Hurricanes have their highest wind speeds on the side where storm pushing winds amplify cyclonic, or counterclockwise, rotational winds.Hurricanes have their highest wind speeds on the side where storm pushing winds amplify cyclonic, or counterclockwise, rotational winds. In coastal areas, flooding is aggravated by the hurricane low pressure triggering higher tides and Ekman transport piling up water.In coastal areas, flooding is aggravated by the hurricane low pressure triggering higher tides and Ekman transport piling up water. The combination of high water, high winds, and enhance transport of water creates a storm surge.The combination of high water, high winds, and enhance transport of water creates a storm surge. Huge waves, high seas, and flooding cause the most damage with a land falling hurricanes and not the high winds.Huge waves, high seas, and flooding cause the most damage with a land falling hurricanes and not the high winds.

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22 Hurricane Watch & Warning The National Hurricane Center in Florida issues a hurricane watch 24 to 48 hours before a threatening storm arrives, and if it appears that the storm will strike within 24 hours, a hurricane warning is issued.The National Hurricane Center in Florida issues a hurricane watch 24 to 48 hours before a threatening storm arrives, and if it appears that the storm will strike within 24 hours, a hurricane warning is issued. While some consider the warning area too large, causing unneeded evacuation, such evacuations have saved many lives.While some consider the warning area too large, causing unneeded evacuation, such evacuations have saved many lives. Hurricane Hugo, with peak winds near 174 knots, caused tremendous damage.Hurricane Hugo, with peak winds near 174 knots, caused tremendous damage.

23 Hurricane Saffir-Simpson Winds In 1989 Hugo caused nearly $7 billion in damages in the U.S., killing 49 in the Caribbean and United States.In 1989 Hugo caused nearly $7 billion in damages in the U.S., killing 49 in the Caribbean and United States. Current classification of hurricanes is based on their wind speed, however, and not on human or property damage.Current classification of hurricanes is based on their wind speed, however, and not on human or property damage. Hurricanes range from category 1 to 5, with winds of 64 to more than 135 knots.Hurricanes range from category 1 to 5, with winds of 64 to more than 135 knots.

24 Hurricane Scale

25 Hurricane Names and Cost Category 5 Hurricane Andrew (1992) was the costliest US storm, but it ranks as less intense than 1935 and 1969 hurricanes.Category 5 Hurricane Andrew (1992) was the costliest US storm, but it ranks as less intense than 1935 and 1969 hurricanes. Hurricane names are chosen from an alphabetical list of male and female names for the Atlantic and Pacific, some of which are retired if the storm was especially damaging.Hurricane names are chosen from an alphabetical list of male and female names for the Atlantic and Pacific, some of which are retired if the storm was especially damaging.

26 Names for Atlantic and Eastern North Pacific tropical systems Atlantic Ocean Basin Name List for Tropical Systems Eastern Pacific Ocean Basin Name List for Tropical Systems

27 Likelihood for Landfall Between 1900 and 2010, only three category 5 hurricanes have made landfall along the Gulf or Atlantic.Between 1900 and 2010, only three category 5 hurricanes have made landfall along the Gulf or Atlantic. Numerous category 1, and less damaging storms, that do make landfall may not cause much damage, but bring needed rainfall.Numerous category 1, and less damaging storms, that do make landfall may not cause much damage, but bring needed rainfall.

28 Decade Saffir-Simpson Scale All 1,2,3,4,5 Major 3,4,5 12345 1851-186085510196 1861-187086100151 1871-188076700207 1881-189089410225 1891-190085530218 1901-1910104400184 1911-1920104430217 1921-193053320135 1931-194047611198 1941-1950869102410 1951-196081530178 1961-197035411146 1971-198062400124 1981-199091410155 1991-200036401145 2001-2006 6 26101597 1851-2006110737518327996 Average Per Decade7.14.74.81.20.217.96.2 U.S. Hurricane Strikes by Decade

29 30 Costliest Contiguous U.S. Hurricanes from 1900 - 2006 (unadjusted) RANKHURRICANEYEARCATEGORYDAMAGE (U.S.) 1KATRINA (SE FL, SE LA, MS)20053$81,000,000,000 2ANDREW (SE FL/SE LA)1992526,500,000,000 3WILMA (S FL)2005320,600,000,000 4CHARLEY (SW FL)2004415,000,000,000 5IVAN (AL/NW FL)2004314,200,000,000 6RITA (SW LA, N TX)2005311,300,000,000 7FRANCES (FL)200428,900,000,000 8HUGO (SC)198947,000,000,000 9JEANNE (FL)200436,900,000,000 10ALLISON (N TX)2001TS5,000,000,000 11FLOYD (Mid-Atlantic & NE U.S.)199924,500,000,000 12ISABEL (Mid-Atlantic)200323,370,000,000 13FRAN (NC)199633,200,000,000 14OPAL (NW FL/AL)199533,000,000,000 15FREDERIC (AL/MS)197932,300,000,000 16DENNIS (NW FL)200532,230,000,000 17AGNES (FL/NE U.S.)197212,100,000,000 18ALICIA (N TX)198332,000,000,000 19BOB (NC, NE U.S)199121,500,000,000 19JUAN (LA)198511,500,000,000 21CAMILLE (MS/SE LA/VA)196951,420,700,000 22BETSY (SE FL/SE LA)196531,420,500,000 23ELENA (MS/AL/NW FL)198531,250,000,000 24GEORGES (FL Keys, MS, AL)199821,155,000,000 25GLORIA (Eastern U.S.)19853900,000,000 26LILI (SC LA)20021860,000,000 27DIANE (NE U.S.)19551831,700,000 28BONNIE (NC,VA)19982720,000,000 29ERIN (NW FL)19982700,000,000 30ALLISON (N TX)1989TS500,000,000 30ALBERTO (NW FL,GA,AL)1994TS500,000,000 30FRANCES (TX)1998TS500,000,000 30ERNESTO (FL,NC,VA)2006TS500,000,000

30 30 Costliest Contiguous U.S. Hurricanes from 1900 - 2006 (adjusted for 2006 standard of living, population growth and wealth normalization) RANKHURRICANEYEARCategoryDamage (Millions) 1SE Florida/Alabama19264$164,839 2N Texas (Galveston)19004104,330 3KATRINA (SE LA, MS, AL)2005385,050 4N Texas (Galveston)1915471,397 5ANDREW (SE FL/LA)1992558,555 6New England1938341,122 7SW Florida1944340,621 8SE Florida/Lake Okeechobee1928435,298 9DONNA (FL/Eastern U.S.)1960428,159 10CAMILLE (MS/LA/VA)1969522,286 11WILMA (S FL)2005321,630 12BETSY (SE FL/LA)1965318,749 13DIANE (NE U.S.)1955118,073 14AGNES (NW FL, NE U.S.)1972118,052 15HAZEL (SC/NC)1954417,339 16CHARLEY (SW FL)2004417,135 17CAROL (NE U.S.)1954316,940 18IVAN (NW FL, AL)2004316,247 19HUGO (SC)1989416,088 20SE Florida1949315,398 21CARLA (N & Central TX)1961414,920 22SE Florida/Louisiana/Alabama1947414,406 23NE U.S.1944313,881 24S Texas1919413,847 25SE Florida1945312,956 26RITA (SW LA/N TX)2005311,865 27FREDERIC (AL/MS)1979310,781 28FRANCES (SE FL)2004210,168 29NC/VA193328,603 30DORA (NE FL)196428,066

31 30 Most Intense Contiguous U.S. Hurricanes from 1851 - 2006 (by lowest observed central pressure) CATEGORYMINIMUM PRESSURE RANKHURRICANEYEAR(at landfall)MillibarsInches 1FL (Keys)1935589226.35 2CAMILLE (MS/SE LA/VA)1969590926.84 3KATRINA (SE LA, MS)2005392027.17 4ANDREW (SE FL/SE LA)1992592227.23 5TX (Indianola)1886492527.31 6FL (Keys)/S TX1919492727.37 7FL (Lake Okeechobee)1928492927.43 8DONNA (FL/Eastern U.S.)1960493027.46 9LA (New Orleans)1915493127.49 9CARLA (N & Central TX)1961493127.49 11LA (Last Island)1856493427.58 11HUGO (SC)1989493427.58 13FL (Miami)/MS/AL/Pensacola1926493527.61 14TX (Galveston)1900493627.64 15RITA (SW LA/N TX)2005393727.67 16GA/FL (Brunswick)1898493827.70 16HAZEL (SC/NC)1954493827.70 18SE FL/SE LA/MS1947494027.76 19N TX1932494127.79 19CHARLEY (SW FL)2004494127.79 21GLORIA (Eastern U.S.)1985394227.82 21OPAL (NW FL/AL)1995394227.82 23FL (Central)1888394527.91 23E NC1899394527.91 23AUDREY (SW LA/N TX)1957494527.91 23TX (Galveston)1915494527.91 23CELIA (S TX)1970394527.91 23ALLEN (S TX)1980394527.91 29New England1938394627.94 29FREDERIC (AL/MS)1979394627.94 29IVAN (AL, NW FL)2004394627.94 29DENNIS (NW FL)2005394627.94

32 25 Deadliest Contiguous U.S. Hurricanes from 1851 - 2006 (causing 25 or greater fatalities) RANKHURRICANEYEARCATEGORYDEATHS 1TX (Galveston)190048000 a 2FL (SE/Lake Okeechobee)192842500 b 3KATRINA(SE LA/MS)200531500 4LA (Cheniere Caminanda)189341100-1400 c 5SC/GA (Sea Islands)189331000-2000 d 6GA/SC18812700 7AUDREY (SW LA/N TX)19574416 h 8FL (Keys)19355408 9LA (Last Island)18564400 e 10FL (Miami)/MS/AL/Pensacola19264372 11LA (Grand Isle)19093350 12FL (Keys)/S TX19194287 j 13LA (New Orleans)19154275 e 13TX (Galveston)19154275 15New England19383 256 15CAMILLE (MS/SE LA/VA)19695256 17DIANE (NE U.S.)19551184 18GA, SC, NC18984179 19TX18753176 20SE FL19063164 21TX (Indianola)18864150 22MS/AL/Pensacola19062134 23FL, GA, SC18963130 24AGNES (FL/NE U.S.)19721122 f 25HAZEL (SC/NC)19544 95 Notes: aCould be as high as 12,000 bCould be as high as 3000 cTotal including offshore losses near 2000 dAugust eTotal including offshore losses is 600 fNo more than

33 Records of the 2005 Atlantic Hurricane Season (Source: NOAA) Most Numerous: * 27 named storms (previous record: 21 in 1933) * 14 hurricanes (previous record: 12 in 1969) * Four major hurricanes hitting the U.S. (previous record: three in 2004) * Three Category 5 hurricanes (previous record: two in 1960 and 1961) * Seven tropical storms before August 1 (previous record: five in 1997) * Two-year consecutive total of tropical storms: 42 (previous record: 32 most recently in 1995-96) * Two-year consecutive total of hurricanes: 25 (previous record: 21 in 1886-87) * Two-year consecutive total of major hurricanes: 13 (ties record in 1950-51) * Two-year consecutive major hurricane landfalls: Seven (previous record: five in 1954-55) * Two -year consecutive Florida major hurricane landfalls: Five (previous record: three in 1949-50) * Three-year consecutive total of tropical storms: 58 (previous record: 43 most recently in 2002-04) * Three-year consecutive total of hurricanes: 31 (previous record: 27 in 1886-88) * Three-year consecutive total of major hurricanes: 16 (ties record in 1949-51 and 1950-52) Costliest: *Hurricane: Katrina (at least $80 billion) - (previous record Andrew, $26.5 billion - 1992 dollars) Deadliest: *U.S. hurricane since 1928: Katrina (at least 1,300) Strongest: * Hurricane in the Atlantic Basin: Wilma 882 millibars (mb) - (previous record: Gilbert at 888 mb) * Three of the six strongest hurricanes on record: Wilma 882 mb (1st), Rita 897 mb (4th), Katrina 902 mb (6th) * July hurricane: Emily (155 mph top sustained winds) - (previous record: Dennis (150 mph) in 2005; Hurricane #1 (140 mph) in 1926

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35 Track positions for Hurricane Katrina, 23-30 August 2005.

36 GOES-12 visible image of Hurricane Katrina over the central Gulf of Mexico at 1745 UTC 28 August 2005, near the time of its peak intensity of 150 kt.

37 Hurricane Wilma Rapid Intensification Over 72 hours 10/19/0510/20/05 10/17/0510/18/05

38 Selected pressure observations and best track minimum central pressure curve for Hurricane Wilma, 15-25 October 2005. Estimates during the extratropical stage are based partially on analyses from the NOAA Ocean Prediction Center. Vertical lines denote landfalls.


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