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Hurricane Hurricane characteristicscharacteristics

Sustained winds of 120 km or moreSustained winds of 120 km or more Sea level pressure < than 990 mbSea level pressure < than 990 mb Varying sizes but cloud shield Varying sizes but cloud shield

usually > 400 km diameterusually > 400 km diameter Warm tropical waters > 27°C (~80)Warm tropical waters > 27°C (~80) Atlantic SeasonAtlantic Season

June – NovemberJune – November Peak: Mid August – Early OctoberPeak: Mid August – Early October

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Hurricane movement & Hurricane movement & dissipationdissipation

Controlled by large Controlled by large surface pressure surface pressure systemssystems Steered by orientation Steered by orientation

and position of and position of subtropical highsubtropical high

Controlled by upper-Controlled by upper-level flowlevel flow

Vary by time of yearVary by time of year Will dissipate over Will dissipate over

land or colder waterland or colder water

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Hurricane genesisHurricane genesis

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Hurricane DevelopmentHurricane Development Coriolis ForceCoriolis Force

Atlantic Formation Atlantic Formation usually between 10 – usually between 10 – 20°N20°N

Water above 27°CWater above 27°C Little wind shearLittle wind shear

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TornadoesTornadoes

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Levels of stormLevels of storm One closed isobar: One closed isobar:

Tropical Depression Tropical Depression (receives number)(receives number)

60 km/h winds:60 km/h winds:Tropical Storm Tropical Storm (receives name)(receives name)

120 km/h winds: 120 km/h winds: HurricaneHurricane

These vary These vary worldwideworldwide

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LandfallsLandfalls

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Storm surge and wind Storm surge and wind variabilityvariability

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Climate change and Climate change and hurricaneshurricanes

????A sign of the futureOr natural variability

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Problems with the Saffir Problems with the Saffir Simpson ScaleSimpson Scale

Pre-landfall Warning ScalePre-landfall Warning Scale Was the storm as strong as advertised?Was the storm as strong as advertised?

Uniform RatingUniform Rating Focuses on wind speed and accompanying Focuses on wind speed and accompanying

surgesurge SURGE discrepancies!SURGE discrepancies! Duration?Duration?

Size?Size? Precipitation?Precipitation? GustsGusts

Surface friction, topographySurface friction, topography