Hurricane Intense storm of tropical origin Winds >64 knots
(74mph) Forms: Warm Northern Atlantic Eastern North Pacific
Oceans
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Eye Eye Wall Spiral Rain bands
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Eye: Calm As move into eye: Air temperature: Increases Wind
speeds: Slow or Slacken Rainfall: Ceases or Stops Sky appearance:
Sky brightens
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Eye Wall: Adjacent to the eye Thunderstorms Whirl around the
center and upward (15km or 49,000)
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Spiral Rain bands: Surface winds: Increase in speed Blow
counterclockwise (Northern Hemisphere) Inward toward its
center
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Hurricanes form: Over warm tropical waters Light winds converge
Humidity is high in a deep layer WINDS ALOFT ARE WEAK Driving
Force: latent heat Hurricane strength: Grow in strength Decrease in
strength
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Hurricanes mostly form over tropical oceans EXCEPT: Southern
Atlantic & Eastern South Pacific North Pacific and North
Atlantic Steered by EASTERLY winds and move WEST
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Hurricane Path: Swing north around the subtropical high Caught
in the westerly flow Actual path: Determined: storm structure and
interaction with the environment Eastern North Pacific: normally
westward away from the coast
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The Hawaiian Islands: Direct path of many eastern Pacific
hurricanes and tropic storms Weaken before hits islands
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Question: Northward moving hurricane over the Atlantic survives
longer than its counterpart at the same latitude over the Eastern
Pacific The surface water over the Atlantic is much warmer
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When on approach from the east: Highest winds are usually on
its north (poleward) Winds propelling storm push added with winds
on the north side and subtract from the winds on the south
(equator) side.
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Gloria 9/27/1985 Moving northward but the net transport of
water directed eastward toward the coast Ekman Spiral and Coriolis
North wind caused a net transport of water toward the shore
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Swells Large waves (10-15m or 33-49ft) Move outward away from
the storm Damage Wind Waves High Seas Flooding
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Flooding (Most destructive) Aided by the low pressure of the
storm Low pressure regions ocean level rise meter Storm Surge High
water + high winds and the net transport of water toward the coast
Storm Surge- abnormal rise of several meters in the ocean level,
which engulfs low-lying areas
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Storm Surge Before During
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Other Damage Tornadoes ~ US hurricanes tornadoes Why? Not quite
known. Surface topography may play a role by initiating the
convergence and so the rising of surface air.
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Hurricane Watch Poses a direct threat to an area 24-48 hours
before the storm arrives National Hurricane Center (Florida)
Pacific Hurricane Center (Hawaii) Hurricane Warning Appears to
strike an area within 24 hours
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Saffir-Simpson Scale Tropical Depression Tropical Storm (given
name) Ranked from 1-5 Category 1- Lowest rank Category 3- Major
hurricane Category 5- Severe damage
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ScaleCentral PressureWindsStorm SurgeDamage mbin.mi/hrknotsftm
198028.9474-9564-824-5~1.5 Damage mainly to trees, shrubbery, and
unanchored mobile homes 2965-97928.5-28.9196-11083-956-8~2.0-2.5
Some trees blown down; major damage to exposed mobile homes, some
damage to roofs of buildings
3945-96427.91-28.47111-13096-1139-12~2.5-4.0 Foliage removed from
trees; large trees blown down; mobile homes destroyed; some
structural damage to small buildings
4920-94427.17-27.88131-155114-13513-18~4.0-5.5 All signs blown
down; extensive damage to roofs, windows, and doors; complete
destruction of mobile homes; flooding inland as far as 10km (6mi);
major damage to lower floors of structures near shore. 5<
920< 27.17>155>135>18>5.5 Severe damage to windows
and doors, extensive damage to roofs of homes and industrial
buildings; small buildings overturned and blown away; major damage
to lower floors of all structures less than 4.5m (15ft) above sea
level within 500m of shore.
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Assigned tropical storm strength Previous naming methods:
Latitudes and longitudes Letters of the alphabet (WWII) By 1953
Female names used using the alphabet
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1978 Eastern Pacific used both male and female 1979 North
Atlantic began this alternating practice as well Names retired
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Hurricanes are tropical cyclones with winds that exceed 64
knots (74mph) Consists of a mass organized thunderstorms that
spiral in toward the extreme low pressure of the storms eye Storms
are given a name at the Tropical Storm category The energy source
that drives hurricanes comes from primarily a release of latent
heat
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In the Northern Hemisphere Hurricanes blow counterclockwise
around the eye In the eye the weather is calm, no rain, no wind,
sunny Eye wall: Intense rain, wind, and thunderstorm Hurricanes
develop in warm tropical waters Hurricanes can spawn tornadoes
Weaken over cold water and land
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Hurricane damage Storm Surge, Wind, Flooding Usually the most
damage is caused by huge waves and flooding with the storm surge
causes the most damage Difference between hurricane and typhoon
Location: western North Pacific areas- typhoon Australia and India-
cyclones