Early Hurricane Notes ATS 553. Hurricane Classification TROPICAL WAVE: –A trough or cyclonic...

Early Hurricane Notes

ATS 553

Hurricane Classification

• TROPICAL WAVE:– A trough or cyclonic curvature maximum in

the tradewinds


• TROPICAL DISTURBANCE:– A discrete system of apparently organized

convection maintained for a day or more


• TROPICAL STORM:– A warm core tropical cyclone with closed

isobars, rotary circulation, and winds between 34 and 64 knots.

– WHEN THEY GET THEIR “NAME”


• HURRICANE/TYPHOON:– A warm core tropical cyclone with closed

isobars, rotary circulation, and winds of at least 64 knots.

– Does not necessarily have an eye, but often does.

Characteristics:

TD TS H

SFC winds <= 34 kt <= 64 kts > 64 kts

Avg. SFC P 1000mb 990mb 960mb

Vis. Features No eye/wall No eye/wall May have eye

Wind shear > 15 kts < 15 kts 0

Vortex Cyclonic throughout

Anticyclonic above 300mb

Active convection

< 1% 1% 4-5%

500mb T Colder than environment

Warmer than environment

Naming Hurricanes

• In the Atlantic:– A, B, C, D…– Alternate boy-girl– Rotate through six lists– Retire names for especially damaging storms

Eastern Pacific

• Very similar scheme as in the Atlantic

Western Pacific

• Just uses a long list

• In alphabetical order BY THE COUNTRY THAT SUBMITTED THE NAME

• Names can be retired, too.

Western Pacific typhoon names

Names in the five lists below are used sequentially from year to year

I II III IV V

Contributed by

Name Name Name Name Name

Cambodia Damrey Kong-rey Nakri Krovanh Sarika

China Longwang Yutu Fengshen Dujuan Haima

DPR Korea Kirogi Toraji Kalmaegi Maemi Meari

Hong Kong, China

Kai-tak Man-yi Fung-wong

Choi-wan Ma-on

Japan Tembin Usagi Kammuri Koppu Tokage

Lao PDR Bolaven Pabuk Phanfone Ketsana Nock-ten

Macau, China

Chanchu Wutip Vongfong Parma Muifa

Malaysia Jelawat Sepat Rusa Melor Merbok

Micronesia Ewiniar Fitow Sinlaku Nepartak Nanmadol

Philippines

Bilis Danas Hagupit Lupit Talas

RO Korea Kaemi Nari Changmi Sudal Noru

Thailand Prapiroon Vipa Megkhla Nida Kularb

U.S.A. Maria Francisco Higos Omais Roke

Viet Nam Saomai Lekima Bavi Conson Sonca

Cambodia Bopha Krosa Maysak Chanthu Nesat

China Wukong Haiyan Haishen Dianmu Haitang

DPR Korea Sonamu Podul Pongsona Mindulle Nalgae

Hong Kong, China

Shanshan Lingling Yanyan Tingting Banyan

Japan Yagi Kajiki Kujira Kompasu Washi

Lao PDR Xangsane Faxai Chan-hom Namtheun Matsa

Macau, China

Bebinca Vamei Linfa Malou Sanvu

Malaysia Rumbia Tapah Nangka Meranti Mawar

Micronesia Soulik Mitag Soudelor Rananim Guchol

Philippines

Cimaron Hagibis Imbudo Malakas Talim

RO Korea Chebi Noguri Koni Megi Nabi

Thailand Durian Ramasoon Hanuman Chaba Khanun

U.S.A. Utor Chataan Etau Kodo Vicente

Viet Nam Trami Halong Vamco Songda Saola

Western Pacific typhoon names

Names in the five lists below are used sequentially from year to year

I II III IV V

Contributed by

Name Name Name Name Name

Cambodia Damrey Kong-rey Nakri Krovanh Sarika

China Longwang Yutu Fengshen Dujuan Haima

DPR Korea Kirogi Toraji Kalmaegi Maemi Meari

Hong Kong, China

Kai-tak Man-yi Fung-wong Choi-wan Ma-on

Japan Tembin Usagi Kammuri Koppu Tokage

Lao PDR Bolaven Pabuk Phanfone Ketsana Nock-ten

Macau, China

Chanchu Wutip Vongfong Parma Muifa

Malaysia Jelawat Sepat Rusa Melor Merbok

Micronesia Ewiniar Fitow Sinlaku Nepartak Nanmadol

Philippines Bilis Danas Hagupit Lupit Talas

RO Korea Kaemi Nari Changmi Sudal Noru

Thailand Prapiroon Vipa Megkhla Nida Kularb

U.S.A. Maria Francisco Higos Omais Roke

Viet Nam Saomai Lekima Bavi Conson Sonca

Cambodia Bopha Krosa Maysak Chanthu Nesat

China Wukong Haiyan Haishen Dianmu Haitang

DPR Korea Sonamu Podul Pongsona Mindulle Nalgae

Hong Kong, China

Shanshan Lingling Yanyan Tingting Banyan

Japan Yagi Kajiki Kujira Kompasu Washi

Lao PDR Xangsane Faxai Chan-hom Namtheun Matsa

Macau, China

Bebinca Vamei Linfa Malou Sanvu

Malaysia Rumbia Tapah Nangka Meranti Mawar

Micronesia Soulik Mitag Soudelor Rananim Guchol

Philippines Cimaron Hagibis Imbudo Malakas Talim

RO Korea Chebi Noguri Koni Megi Nabi

Thailand Durian Ramasoon Hanuman Chaba Khanun

U.S.A. Utor Chataan Etau Kodo Vicente

Viet Nam Trami Halong Vamco Songda Saola

Other Basins

• Use other schemes

• Usually just short lists that they rotate through as needed

Historically:

• Prior to WWII, storms were named after the patron saint of the day.

• Post WWII, various schemes:– Phonetic alphabet (alpha, bravo, charlie..)– Animals (Antelope, Bear, Cat, Dog…)– Adjectives (Aggressive, Blusterly…)– All Female Names starting in the mid 1950s– Male names started in 1979

Tropical Cyclones vs. Midlatitude Cyclones

• Strongest Winds:– MC: Jet Stream– TC: Surface


• Core Temperature:– MC: Cold core (trough)– TC: Warm core (LHR in eyewall, subsidence

in eye)


• Structure:– MC: Asymmetric, fronts– TC: Symmetric, no fronts


• Scale:– MC: Synoptic scale– TC: Mesoscale in size, synoptic scale in

duration

Why Winds Decrease With Height In A Hurricane

ATS 553

Warm Core Systems

Temperature Gradient!

From Above…

What if this were a regular warm front?

• What would the Thermal Wind relationship tell us about how winds would be changing with respect to height?


• Wind speeds at the surface would be weak.

• Aloft, there would be a Midlatitude Jet Stream!

Winds would be getting more positive with height!


Wind Speed

Hei

gh

t

0

But This Is NOT a Midlatitude Cyclone

Strong Surface Winds

With height, these winds DECREASE due to the Thermal

Wind Relationship!

Strong Surface Winds…

…get weaker with height…

…even reverse aloft..

…to create the upper-level anticyclone!

Wind Profile:

Wind Speed

Hei

gh

t

0

Hurricane Cookbook

• 1. High SSTs (at least 26°C)– Flux of sensible and latent heat

– Hurricanes do NOT “seek out” warm water

Hurricane Cookbook

• 2. Coriolis Force (at least 5° off of the equator)– Hurricanes are in CYCLOSTROPHIC

balance, not GEOSTROPHIC BALANCE– However, Coriolis Force keeps the winds from

just following directly into the region of low pressure when it first forms.

– Hurricanes don’t FORM at the equator.– Hurricanes don’t CROSS the equator!

Hurricane Cookbook

• 3. Instability– Rules out subtropical highs, which are regions

of sinking motion and high stability

– KNOW WHY SINKING MOTION IS ASSOCIATED WITH INCREASED STABILITY!

Hurricane Cookbook

• 4. No wind shear– Redistributes vertical profile of latent heat

release, setting up the wrong circulation patterns

– TUTT—Tropical Upper Tropospheric Trough

TUTT– June thru August

Hurricane Cookbook

• 5. High relative humidities through midlevels of the troposphere– Helps reduce the impact of entrainment.– Individual Cumulus towers are easily

destroyed by entrainment of dry air.

Hurricane Cookbook

• 6. An initial disturbance– Unorganized groups of thunderstorms

organize into tropical storms.

– Typically these are West African Squall Lines or other disturbances in the AEJ.

Saffir-Simpson Scale

Early Hurricane Notes ATS 553. Hurricane Classification TROPICAL WAVE: –A trough or cyclonic...

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