a

1. 1
Carl Schreck
Lifecycle Ingredients Climatology Data

2. 2
Lifecycle Ingredients Climatology Data

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

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

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 Climatology Data

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 Climatology Data

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 Climatology Data

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 Climatology Data

9. 9
 Wind shear is defined as the wind vector
difference between the 850 and 200 mb
level (arbitrary)
High westerly shear Low 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 Climatology Data

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 Climatology Data

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 Climatology Data

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 Climatology Data

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

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 Climatology Data

15. 15
Lifecycle Ingredients Climatology Data

16. 16
Lifecycle Ingredients Climatology Data

17. 17
Lifecycle Ingredients Climatology Data

18. 18
Lifecycle Ingredients Climatology Data

19. 19
Lifecycle Ingredients Climatology Data

20. 20
Lifecycle Ingredients Climatology Data

21. 21
Lifecycle Ingredients Climatology Data

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 Climatology Data

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 Climatology Data

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 Climatology Data

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