Terminology

Terminology

Tropical disturbance - cluster of thunderstorms, weak pressure gradients, no real rotation

Tropical depression - at least one closed isobar, windsless than 39 mph

Tropical storm - a depression with winds stronger than 39-73 mph

Hurricane - winds stronger than 74 mph

Anita (September 1977) in central Gulf of Mexico

Notice the apparent guidance by the Azore High

A Suggestive Overview

SST and Tropical Systems

A weather system for which a tropical cyclone forecast center (NHC, CPHC, or JTWC) is interested in collecting specialized data sets and/or running model guidance.

Once a system has been designated as an invest, data collection and processing is initiated on a number of sites (eg. Naval Research Laboratory, U. Wisc. Cooperative Institute for Meteorological Satellite Studies (UW-CIMSS).

Designation as an invest does not correspond to any particular llikelihood of development of the system into a tropical cyclone.

“Invest”

Saffir-Simpson Scale -1

Tropical Storm 39-73 mphHurricanes:

Category 1 74-95 mph Minor damage to buildings; damage tounanchored mobile homes, signs; somecoastal flooding and minor pier damage.

Category 2 96-110 mph

Some damage to building roofs, doors and considerable damage to mobile homes; flooding, damaged piers, small unprotected craft may break moorings, some trees blown down.

(See text p 157)

Category 3 111-130 mph Damage to small residences and utility buildings. large trees blown down. Mobile homes destroyed. flooding near coast destroys smaller structures, larger structures damaged by floating debris. - Examples: Keith 2000, Fran 1996, Opal 1995

Category 4 131-155 mph Some complete roof structure failure on small residences; major erosion of beach areas; Terrain may be flooded well inland. - Examples: Hugo 1989 and Donna 1960

Category 5 156 mph and up Complete roof failure on many residences and industrial buildings; some complete building failures; small utility buildings blown over or away; flooding causes major damage to lower floors of all structures near the shoreline. Massive evacuation of residential areas may be required. - Examples: Katrina, Andrew(FL) 1992, Camille 1969

Saffir-Simpson Scale (cont.)

Surge

Saffir-Simpson Scale (Summary)

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Highest activity: NH western tropical PacificLowest activity: SH Atlantic

Global Hurricane Tracks 1995-2005

Hurricanes around the globe.

Global “Hurricane Seasons”

Atlantic: TS & Hurricanes 1851-2004 (1325)

North Atlantic Climatology

10

10

Average Cumulative Number/Yr

Atlantic Eastern Pacific

(www.nhc.noaa.gov/pastprofile.shtml)

Vertical Shear Over Atlantic









June Sept

OctAug

Atlantic: Shear and SST









August September

Named=yellow; hurricanes=green; cat 3 or greater = red

Atlantic TS & Hurricanes 1851-2004

Prevailing Tracks





250mb 850mb

July



Surface Temp

August







September







October







November







Hurricane Strikes 1926-2005

Western Gulf

Eastern Gulf

“Return Period”

Scales of Motion



Scales of Motion (2)







Structure (Mature)




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extratropical tropical

“Life Cycles”










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Midlatitude Cyclone

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Terminology