1. 1 Carl Schreck Lifecycle Ingredients ClimatologyData

2. 2 Lifecycle Ingredients ClimatologyData

3. 3  Winds < 35 kts  Numbered, but not named  Semi-organized group of thunderstorms Lifecycle Ingredients ClimatologyData

4. 4  Winds 35–63 kts  ≈ 11 per year in the Atlantic  Named  More circular/spiral, but no eye Lifecycle Ingredients ClimatologyData

5. 5  Winds ≥ 64 kts  ≈ 6 per year in the Atlantic  Eye develops  Different names around the world:  Hurricane in the Atlantic and East Pacific  Typhoon in West Pacific  Cyclone in Indian Ocean and South Pacific  “Tropical Cyclone” is the generic/scientific term Lifecycle Ingredients ClimatologyData

6. 6  Winds ≥ 96 kts  ≈ 2-3 per year in the Atlantic  Category 3–5 on the Saffir–Simpson Scale  Strong and dangerous storms  Well-defined, circular eye Lifecycle Ingredients ClimatologyData

7. 7  Deep warm ocean layer  Warm oceans are the energy source for hurricanes  But hurricanes can mix cold water upward if the warm water is too shallow  Conditionally unstable atmosphere  Warm air rises, but only if it’s warmer than its surroundings  Moist mid-troposphere  Dry air 2-3 km from the surface can cause cold downdrafts ww2010.atmos.uiuc.edu Lifecycle Ingredients ClimatologyData

8. 8  Pre-existing convection  Needs organized thunderstorms to get things going  Cyclonic low-level vorticity  Counter-clockwise spinning winds help organize the thunderstorms  Associated with low pressure  Weak vertical wind shear  Tilting winds can knock the storm over Lifecycle Ingredients ClimatologyData

9. 9  Wind shear is defined as the wind vector difference between the 850 and 200 mb level (arbitrary) High westerly shearLow easterly shear In general, low values (< 20 kt) of vertical wind shear are desired. Bad – convection torn apart Good – latent heat can concentrate in one area Courtesy of C.C. Hennon, UNC Asheville Lifecycle Ingredients ClimatologyData

10. 10  Thunderstorm systems with wave-like properties  Move westward with a period of 3–6 days  Common over West Africa  Provides storms with cyclonic vorticity and convection Berry et al. (2007, Mon. Wea. Rev.) Lifecycle Ingredients ClimatologyData

11. 11  Warm Ocean Temperatures  Supply of Tropical Waves from Africa  10°N to 20°N  20°W to 60°W or 80°W Lifecycle Ingredients ClimatologyData

12. 12  Dry air from Sahara can weaken storms  Dust blocks the sun and cools the ocean Zipser et al. (2009, BAMS) climate.nasa.gov Lifecycle Ingredients ClimatologyData

13. 13 Knapp et al. (2010, BAMS) Lifecycle Ingredients ClimatologyData

14. 14  Bars depict number of named systems (open/yellow), hurricanes (hatched/green), and category 3 or greater (solid/red), 1886-2004 nhc.noaa.gov/climo Lifecycle Ingredients ClimatologyData

15. 15 Lifecycle Ingredients ClimatologyData

16. 16 Lifecycle Ingredients ClimatologyData

17. 17 Lifecycle Ingredients ClimatologyData

18. 18 Lifecycle Ingredients ClimatologyData

19. 19 Lifecycle Ingredients ClimatologyData

20. 20 Lifecycle Ingredients ClimatologyData

21. 21 Lifecycle Ingredients ClimatologyData

22. 22  Historical record of tropical cyclone locations and intensities  Constructed after each season by the warning agencies  Best estimate using all available data nhc.noaa.gov Lifecycle Ingredients ClimatologyData

23. 23  Weather stations  Buoys  Ships  Radar  Aircraft Reconnaissance  Visible/Infrared Satellites  Microwave satellites  Satellite estimates account for vast majority of the record Courtesy of Jack Beven (NOAA/NHC) Lifecycle Ingredients ClimatologyData

24. 24  Weather stations  Buoys  Ships  Radar  Aircraft Reconnaissance  Visible/Infrared Satellites  Microwave satellites  Satellite estimates account for vast majority of the record Courtesy of Jack Beven (NOAA/NHC) Lifecycle Ingredients ClimatologyData

25. 25 Which image on the right is the closest match for this image of Hurricane Katrina?