WEATHER BRIEF FOR TBEC

12 November 2013,Nuku’alofa

‘Ofa Fa’anunu

Tonga Met ServiceMINISTRY OF INFRASTRUCTURE

RAINFALL

Mean annual rainfall for Tonga's main islands (1971-2000)

2453

2374

2150

1619

1721

0 500 1000 1500 2000 2500 3000

Niuafo'ou

Keppel

Vava'u

Ha'apai

Tongatapu

Isla

nd g

roup

mm

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC0

50

100

150

200

250

FUA'AMOTU AVERAGE RAINFALL FOR 1971-2000

AVERAGE

MONTH

MM

DRY DRY

Seasonal Cycles

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Seasonal Cycles

NIUAFOOU NIUATOPUTAPU VAVAU

HAAPAI NUKU’ALOFA

NFO = ABOVE 1001MMNTT = ABOVE 864MMVAV= ABOVE 8I3MMHAP= ABOVE 580MMTBU = ABOVE 565MM

TROPICAL CYCLONES

What is a tropical cyclone?

Tropical Cyclone = wind circulation around a centre > 34kts

Warnings Wind speed

Gale warning = 34-47kt

Storm warning = 48-63kt

Hurricane warning = >64kt

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A Tropical Cyclone will be categorized as per the Australian and South Pacific

Category System as follows: Category Potential damage

10-Min Mean Wind Maximum 3-Sec Gust

Category 1 (Tropical Cyclone)

(Negligible house damage. Damage to some crops and trees. Boats may drag anchor e. g. TC CILLA)

63 – 87 km/hr (34 – 47 knots)

Less than 125 km/hr (Damaging Winds)

Category 2 (Tropical Cyclone)

(Minor house damage. Significant damage to trees. Heavy damage to crops. Risk of

power failure. Small boats my break anchor e. g. TC HINA)

88 – 117 km/hr (48 – 63 knots)

125-169 km/hr (Destructive Winds)

Category 3 (Severe Tropical Cyclone)

(Some roof and structural damage. Power failure likely e. g. TC KINA)

118 – 157 km/hr (64 – 85 knots)

170-224 km/hr (Very Destructive Winds)

Category 4 (Severe Tropical Cyclone)

(Significant roofing loss and structural

damage, Dangerous airborne debris e. g TC WAKA)

159 – 200 km/hr (86 – 110 knots)

225-279 km/hr (Very Destructive Winds)

Category 5 (Severe Tropical Cyclone)

(Extremely dangerous with widespread destruction. e. g. TC HETA)

Over 200 km/hr) (Over 110 knots)

Over 280 km/hr (Very Destructive Winds)

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Impacts and Extremes

Average number of tropical cyclones per season (66 years)

El Nino 1.88 La Niňa 1.63 Neutral 1.64

All seasons

1.74

Tropical Cyclone Outlook for 2013/14

Average to Below average no of TCs expected in the SW Pacific (mod confidence);

TC risk is higher than normal for the countries west of and around the Dateline;

4 to 8 named tropical cyclones expected this season;

Average to above average activity for Tonga

Tropical Cyclone Outlook for 2013/14

Chance of getting a cyclone in Tonga this season is 114% (High). Likely 2

Severe TC Risk for Tonga 171% (Very High);

Cyclone formation and track will most likely be from west to north quadrant

TC Season for 2013/14 similar conditions to

1981/82 - TC Isaac (Severe – C&S Tonga) 1984/85 - TC Lance (Storm), TC Drena

(Storm) both N.Tonga, TC Eric (Severe – C&S Tonga)

1990/91 – TC Sina (Severe – C&S Tonga), TC Val (Severe – Northern Tonga)

1996/97 – TC Hina (Severe Southern Tonga), TC Keli (June) (Severe N.Tonga)

2001/02 – TC Waka (Severe N&C Tonga)

TSUNAMI

2 natural cuts in the reef

PACCSAP Project

Nukualofa

Sea flooding already affectsNuku’alofa from subsidence even before the tsunami arrives

After modeling

• Confirmed extreme tsunami risk for Tongatapu

• There are wave depths of >10m in places and several km inland depending on local topography.

• Nuku’alofa and eastern Tongatapu are most vulnerable.

• Warning times will be very limited (10-25 minutes)

• There are several small pockets of safer (higher) ground

WILL NOT WORK IN A

LOCAL EVENT

Detecting a local tsunami

• Tonga seismic network problematic (5 seismic stations) & no direct access by warning center

• Earthquake data from USGS

• Geological Survey Unit send an automatic message through HYDRA system (often can receive a preliminary center & magnitude quicker than PTWC)

• Warning center looking to using earthquake intensity meters to measure ground shaking as an early warning indicator

• Sea Level monitoring equipment to be improved through SPCR Project

Current warnings

1) Urgent Tsunami Alert

– Ready made and ready to go (TMS)

2) Tsunami Warning

- As received by PTWC

(3) Local Earthquake Bulletin – Anything above 4.5M and below 70km depth

(4) PTWC international SMS direct to mobile

phone

Future warnings (from later 2014)

1) Urgent Tsunami Warning (ready made)

2) Tsunami Warning (when verified)

(3) Local EQ Advisory (4.5 <M<7.5) <50km

(4) Regional EQ Advisory (M>7.5) <50km

(5) Distant EQ Advisory

(6) Tsunami No threat Advisory

(7) Tsunami Marine Warning

Disseminating the warnings

• 24hr SMS mobile alert service via 1 Telecom provider (Digicel) to selected users relevant to the warning system

• Live broadcast on national radio (Radio Tonga) – national coverage (both MET and NEMO)

• Activation of sirens in place

• Met Service Website

• Email distribution

• Telefone/fax

KALAA’U

KALA’AUFAHEFA

THIS ROCK IS THOUGH TO BE BROUGHT BY A TSUNAMI

Things to do in an earthquake or tsunami in Tonga

• When there is an earthquake find something solid and lie down next to it. Do not go underneath table or bed etc

• If the earthquake is strong enough for you to loose balance, move away from the coast immediately a tsunami might be on its way in less than 15mins

Things to do in an earthquake or tsunami in Tonga

• Move inland by 1 mile and wait there. Listen to radio. If no radio then wait there for an hour

• Know where you live. Be aware of high strong buildings. Even tall trees you can climb

• If you are on a small island, move to the centre of the island a find a strong tree to climb

Things to do in an earthquake or tsunami in Tonga

• Be aware of what the wildlife and animals are doing. Often their senses are keener than humans

• If u are at sea and you hear a tsunami warning stay out at sea, you are safe there

• Do not drive when evacuation your home….WALK!!

Things to do in an earthquake or tsunami in Tonga

• Teach your family about tsunami and where to evacuate. You should not pickup your school children from school in an event of a tsunami

• All tsunami are dangerous. Large or Small. Heed warnings at all times

• Tsunami is not just one wave. It is a series of waves and the first is not necessarily the biggest

Things to do in an earthquake or tsunami in Tonga

• If you see the tide receding after a major earthquake..RUN!!

• Do not attempt to go and see a tsunami. On level ground, when you see a tsunami is usually too late to escape

MALO AUPITO