Overall Red alert Tropical Cyclone for GITA-18
in Tonga

Impact

Tropical Cyclone GITA-18 can have a high humanitarian impact based on the maximum sustained wind speed,exposed population and vulnerability.

Meteorological source GDACS (JTWC)
Exposed countries Tonga
Exposed population 80 thousand in Category 1 or higher
Maximum wind speed 231 km/h
Maximum storm surge 0.4 m (12 Feb 12:00 UTC)
Vulnerability Medium (Tonga)

GDACS Score

GDACS alert score for Tropical Cyclones is 0.5 (GREEN Alert), 1.5 (ORANGE Alert), 2.5 (RED Alert)
For more info on GDACS alert score click here.
  Wind Storm surge Rainfall GDACS score
GDACS Current 139 km/h 0.3 m n.a. 1.5
GDACS Overall 231 km/h 0.4 m n.a. 1.5

Maximum winds, storm surge, rainfall (Current: over the next 72 h, Overall: entire TC track)

Wind

139 km/h Current

Up to 83000 people in Category 1 strength or higher (see SSHS)

Impact Timeline

Alert Date (UTC) Max Winds (km/h) Population in
Tropical Storm
Population in
Cat. 1 or higher
Countries
Orange 1 09 Feb 2018 00:00 120 390 thousand 80 thousand Tonga
Orange 2 09 Feb 2018 06:00 148 400 thousand 80 thousand Tonga
Orange 3 09 Feb 2018 12:00 148 930 thousand 80 thousand Tonga
Orange 4 09 Feb 2018 18:00 139 830 thousand 80 thousand Tonga

Bulletin Timeline

Alert Date (UTC) Category Max winds
(km/h)
Population in
Tropical Storm
Population in
Cat.1 or higher
Location (lat, lon) Countries
GREEN
1 09 Feb 2018 00:00 Tropical storm 74 260000 people no people -13.8, -175.5 American Samoa
GREEN
2 09 Feb 2018 06:00 Tropical storm 74 260000 people no people -14.3, -174.5 Niue
GREEN
3 09 Feb 2018 12:00 Tropical storm 83 250000 people no people -14.5, -173 Niue
GREEN
4 09 Feb 2018 18:00 Tropical storm 83 250000 people no people -15.3, -171.4 Niue
GREEN
4 10 Feb 2018 06:00 Tropical storm 102 150000 people no people -17.2, -169.1 Niue
GREEN
4 10 Feb 2018 18:00 Category 1 120 1100 people no people -19.7, -168.5 Niue
GREEN
4 11 Feb 2018 06:00 Category 1 130 100000 people no people -21.2, -169.3 Niue
ORANGE
4 11 Feb 2018 18:00 Category 1 139 110000 people 82000 people -21.7, -171.4 Tonga
GREEN
4 12 Feb 2018 18:00 Category 1 148 560000 people <1000 people -21.3, -176.4 Fiji
GREEN
4 13 Feb 2018 18:00 Category 2 157 460000 people no people -21.4, 179.5 Fiji
GREEN
4 14 Feb 2018 18:00 Category 1 148 no people no people -22.9, 175.7
Actual track of the current bulletin
The alert for forecast greater than 3 days is limited to Orange level.



Exposed population

Countries

Country
Tonga

Provinces

Region Province Country Population
Tonga Tonga 98000 people

Populated places

Name Region Province Country City class Population Distance
Nuku'alofa Tonga Capital 24000 people 762 km

Critical infrastructure

Airports, ports, nuclear plants and hydrodams at risk, if affected, are listed below.

Airports

Name IATA Code Elevation (m) Usage Runway type IFR Runway Length (ft) Distance
Fua'amotu International TBU 38 Civ. Paved Yes 8700 767 km
Eua Kaufana EUA unknown 0 771 km
Ono-I-Lau ONU unknown 0 974 km

Ports

Name LOCODE Country Distance
Nuku'alofa TOTBU Tonga 761 km
Eua Island Tonga 767 km

Rainfall

Rainfall accumulation of the past 24h, as detected by the Global Precipitation Measurement mission of NASA. For more information, see https://www.nasa.gov/mission_pages/GPM/main/index.html.

...

StormSurge

0.4 m

The maximum Storm surge height is  0.3m in Fuaamotu, Tonga. This height is estimated for 12 Feb 2018 12:00 UTC .

The JRC has developed an experimental global storm surge model, which is run after each advisory issued by the regional tropical cyclone centres. The calculations are published about 20 minutes after a new advisory is detected by GDACS. The calculations identify the populated places affected by storm surge up to three days in advance, using the forecasted track. When forecasts change, the associated storm surge changes too and alert levels may go up or down. All links, data, statistics and maps refer to the latest available calculation. If the calculation for the last advisory is not completed, the latest available calculation is shown.

Locations affected by Storm surge (14 locations). Calculation based on advisory number 4 of 09 Feb 2018 18:00:00 UTC. (Simulation using 0.5 minute resolution)

Alert Date (UTC) Name Country Storm surge height (m)
12 Feb 2018 12:00 Fuaamotu Tonga  0.3
12 Feb 2018 12:00 Mua Tonga  0.3
12 Feb 2018 12:00 Fatumu Tonga  0.3
12 Feb 2018 12:00 Kolonga Tonga  0.3
12 Feb 2018 12:00 Niutoua Tonga  0.3
12 Feb 2018 12:00 Ohonua Tonga  0.3
12 Feb 2018 14:00 Foui Tonga  0.3
12 Feb 2018 12:00 Nukunuku Tonga  0.3
12 Feb 2018 12:00 Houma Tonga  0.3
12 Feb 2018 12:00 Pea Tonga  0.3
12 Feb 2018 12:00 Nuku'alofa Tonga  0.3
09 Feb 2018 01:00 Mua Wallis and Futuna  0.1
09 Feb 2018 01:00 Mata-Utu Wallis and Futuna  0.1
09 Feb 2018 13:00 Fuailalo Samoa  0.1