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 09:00 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 148 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

148 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

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
3 10 Feb 2018 00:00 Tropical storm 102 250000 people no people -15.8, -170.1 Niue
GREEN
3 10 Feb 2018 12:00 Category 1 130 55000 people no people -18.1, -168.7 Niue
GREEN
3 11 Feb 2018 00:00 Category 1 139 12000 people no people -20.3, -168.9 Niue
ORANGE
3 11 Feb 2018 12:00 Category 1 148 100000 people 82000 people -21.4, -170.8 Tonga
ORANGE
3 12 Feb 2018 12:00 Category 1 148 560000 people 83000 people -21.3, -175.6 Tonga
GREEN
3 13 Feb 2018 12:00 Category 2 157 550000 people no people -21.1, -179.9 Fiji
GREEN
3 14 Feb 2018 12:00 Category 2 157 no people no people -21.9, 176.2
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 771 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 780 km
Eua Kaufana EUA unknown 0 789 km
Ono-I-Lau ONU unknown 0 910 km

Ports

Name LOCODE Country Distance
Nuku'alofa TOTBU Tonga 770 km
Eua Island Tonga 786 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 09:00 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 3 of 09 Feb 2018 12:00:00 UTC. (Simulation using 0.5 minute resolution)

Alert Date (UTC) Name Country Storm surge height (m)
12 Feb 2018 09:00 Fuaamotu Tonga  0.3
12 Feb 2018 09:00 Mua Tonga  0.3
12 Feb 2018 09:00 Fatumu Tonga  0.3
12 Feb 2018 09:00 Kolonga Tonga  0.3
12 Feb 2018 09:00 Niutoua Tonga  0.3
12 Feb 2018 09:00 Ohonua Tonga  0.3
12 Feb 2018 12:00 Foui Tonga  0.3
12 Feb 2018 10:00 Nukunuku Tonga  0.3
12 Feb 2018 10:00 Houma Tonga  0.3
12 Feb 2018 10:00 Pea Tonga  0.3
12 Feb 2018 10:00 Nuku'alofa Tonga  0.3
09 Feb 2018 14:00 Fuailalo Samoa  0.1
09 Feb 2018 01:00 Mua Wallis and Futuna  0.1
09 Feb 2018 01:00 Mata-Utu Wallis and Futuna  0.1