1. Global Change Impacts: SE U.S. Weather & Climate Judith Curry Georgia Institute of Technology

2. The “hockey stick” curve (IPCC, 2001) Global surface temperatures for the last 100 years are unprecedented in the last millennia Mann et al. (1999)

3. Attribution of warming from climate model experiments Warming after 1970 is attributed to greenhouse gases Meehl et al, 2004: J. Climate.

4. Impacts of global warming on SE U.S. weather & climate a) Increase in mean surface temperature b) More severe and longer lasting droughts c) Sea level rise d) Increased hurricane activity

5. 0.5±0.25ºC Sea surface temperature in global tropics Increase of 1 o F in global tropical SST since 1970

6. Global increase in hurricane intensity Webster, Holland, Curry, Chang, Science, 9/16/05 # of cat 4+5 hurricanes has doubled globally since 1970

7. Relationship between # of Atlantic storms and sea-surface temperature 1 o F increase in temperature --> +5 tropical storms

8. SST TS AMO: quasiperiodic peaks 1880, 1950, (2020) ABO: minima 1935, 1955, 1975, 1995, (2015) AGW: global warming trend since 1970 |----------------------------| |------------------------------| |----- Atlantic multidecadal oscillation (AMO)

9. Peak Periods of N. Atlantic Hurricane Activity 1945-1955 1995-2005 #Tropical storms 115 165 # Hurricanes 74 112 # Category 3+4+5 41 45 # Category 4+5 19 28

10. 2005 Atlantic Hurricane Records o Total named storms: 28 (21) Hurricanes: 15 (12) Category 5 storms: 4 (2) Strongest storm: 185 mph (Wilma) Total damages: > US $200B

11. http://weatherunderground.com/tropical 2005 season: Five Gulf Category 4-5 storms

12. Hurricane Katrina Sea surface temperatureDepth of warm layer Hurricane Katrina intensified when it crossed the warm, deep Loop Current R. Scharoo

13. Systematic lengthening of the North Atlantic hurricane season 1851-2005, 10 yr running mean Since 1915, there is an increase of 4.8 days/decade

14. U.S. Landfalling Hurricanes 1851-2004, 10 yr running mean P. Agudelo SST

19. 100 mph 120 mph 140 mph 160 mph

20. TC-Induced Tornado Climatology NE Quadrant is preferred location– ambient helicity is maximized (Novlan and Gray 1974)(McCaul 1991) 74% of post-landfall tornadoes reported from 1964 to 1983 were associated with outer-band convection (Weiss 1987) Optimum range for outer-band tornadoes is 120 to 240 miles from the center of the TC (Spratt et al. 1997) 87% of all tornado-producing TC make landfall in the Gulf rather than the Atlantic (Hagemeyer and Hodanish 1995). Hurricane-induced tornadoes NE quadrant is preferred location for tornadoes Optimum range for tornadoes is 120-240 miles from eye 87% of all hurricane-induced tornadoes assoc. with landfall in the Gulf

21. 2. Tornadoes can occur several days after landfall. ** Hurricane Ivan made landfall in Gulf Shores, AL at 1:50 am on 09/16/04. The last tornado occurred ~ 49 hours after landfall & ~ 1,000 mi from landfall! Why are TC-Induced Tornadoes Important? Tornadoes can occur several days after landfall Hurricane Ivan made landfall in Gulf Shores, AL at 1:50 a.m. 9/16/04. The last tornado occurred 49 hours later, 1000 mi from initial landfall.

22. 3 landfalls since 1851 (but none since 1900); but substantial increases in the number of storms increases the probability of a GA landfall Landfall on GA coast has potential for big storm surge owing to shallow shelf Barrier islands at extra risk associated with sea level rise Heavy rainfall associated with storms that make landfall in the Gulf Tornadoes likely to be spawned in GA by intense storms that make landfall in the Gulf; this will become more likely as storm intensity increases and a higher proportion of storms enter the Gulf Risks to Georgia