World Meteorological Organization RA V TROPICAL CYCLONE COMMITTEE FOR THE SOUTH PACIFIC AND THE SOUTH-EAST INDIAN OCEAN Seventeenth Session Nouméa, New Caledonia, France, 23 to 26July 2018 RA V/TCC-17/Doc. 4.2(x) Submitted by: RAV TCC Members XX.VI.2018 DRAFT 1 AGENDA ITEM NO.4: REVIEW OF THE 2016/2017 AND 2017/2018 CYCLONESEASONS AGENDA ITEM NO.4.2: COUNTRY REPORT AGENDA ITEM NO.4.2.(X): SAMOA Members who have experienced impacts of tropical cyclones and/or other severe weather events during these two seasons will be invited to submit to the session concise reports on operations, functioning, interactions and coordination with stakeholders, and lessons learned from their National Warning Systems and Services during these events, including measures already taken as a consequence and proposals. The Committee may wish to review these reports and discuss operational matters and shortcomings with a view to improving national early warning services. 1. Impacts related of tropical cyclones or other severe weather events SAMOA TROPICAL CYCLONE SEASON NOVEMBER 2016 - APRIL 2017 1.1 INTRODUCTION The season 2016-2017 officially start from 1 st November 2016 until 30 th April 2017 with a total of 22 tropical disturbances were monitored within the region together with disturbances formed over Australia region and moved over the region. From these 22 disturbances, there were 4 named tropical cyclone monitored on the month of February (TC Bart), April (TC Cook) and May (TC Donna, TC Ella) In overall, the most active period of the season in terms of cyclone formation actually occurred outside the official bounds of the season, with both Severe Tropical Cyclone Donna and Tropical Cyclone Ella being named in May 1.1.1 (a) TROPICAL DEPRESSION 05F (23/12/2016-01/01/2017) A low pressure system was analyzed southeast of Samoa near Southern Cooks on the 22nd of December 2016, then later upgraded into a Tropical Depression on the next day. The system remained as a Tropical depression until it was downgraded into a low pressure system on the 28th as it moved south-southeast to the south of Southern Cooks before drifting southwestward. Samoa was not directly impact by the aforesaid system but an active convergence which was also links to it with associated massive cloud band caused heavy downpour across the Samoa island chain on the 31st. No special weather bulletin was issued, however, a heavy warning was issued on the early morning on the 23rd until the first day of January 2017. A broad area of low pressure was
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 2 located south of the island but an active cloud band with embedded severe thunderstorms was over Samoa associated with the above mentioned convergence zone. Rainfall observation recorded a tremendous amount of rainfall throughout the country where nearly all stations recorded more than 100mm/24hrs on the 31st Dec 2016, the highest rainfall amount was recorded from the Northwest of Savai'i of 258.2mm and three other stationsrecorded more than 200mm.This event leads to severe flooded to low lying areas and unexpected level of overflow rivers and small streams. Figure1.1.1: SMD Surface Streamline analysis. Figure1.1.2: Satellite image. (b) TROPICAL DEPRESSION 09F (08/02/2017-13/02/2017) On Monday 06th of February 2017, a Tropical Disturbance 09F was analysed a few hundred miles southeast of Fiji along the trough extending from Solomon Is.The system was upgraded into a Tropical Depression on the 10th Feb with no further development as it remained nearly stationary to the southeast of Fiji Island. An active feeding cloud band spiral towardstd09f resulted into strong cross equatorial northwest flow and a convergence zone over Samoa. This system lead to the issuance of a heavy rain warning and the Small Craft advisory due to gusty winds and developing swells on the 8th Feb, wind advisory was later enforced on the next day. Surface observation revealed the severity of the system where four Manual and AWS station recorded more the 100mm/24hrs rainfall amount on the 9th Feb with the highest of 138.4mm from Afimalu station (central highland-upolu Island)and observed the maximum wind of 46kmph (25knots) at the northern facing shore.
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 3 Figure1.2.1: SMD Surface Streamline analysis. Figure1.2.2: ASCAT pass observed more than 25knot to the North of the island. Figure1.2.3: Satellite image shows deep convection over Savaii. (c) TROPICAL DEPRESSION 12F & 14F (17/02/17-23/02/17) On Saturday 18 th Feb 2017,two cyclonic circulation along the SPCZ axis was formed south of Fijiwater and both advanced into a Tropical Depression without further intensification. The coupling of the two tropical depression caused TD14Fto move east northeast towards south of Samoa while TD12F being pushed west of Fiji on the 22nd of Feb. Another low pressure system was also located just southeast of Samoa at the meantime, causing a tighten pressure gradient over Samoa, resulted in extremely wet weather condition and gusty north-westerly winds flow. A massive band of convective cloud covers Samoa island from the 19th-23rd of Feb 2017 and produced a wide-spreadamount of rainfall and gusty winds across the island. Wind advisory, Heavy rain warning and small crafts advisory was valid on the 17th Feb before the arrival of the expected weather condition. Highest rainfall amount was recorded from Afimalu on the 17th Feb of 126.0mm and Lepiu on the 19th & 23rd Feb of 122.5mm and 107mm. Strong and gusty winds recorded on the Northern side of 57.9kmph (30.3knots) on the 20th Feb and 59.5kmph (32.1knots) on the 22nd of Feb 2016.
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 4 SAMOA Figure1.3.1: Fiji Met Isobar Figure: 1.3.2: VIS Satellite image. Figure: ASCAT pass shows strong Northwest winds moving over Samoa. (d) TROPICAL DEPRESSION 19F (04/04/2017-07/04/2017) An active portion of the SPCZ was located just North of Samoa with embedded low pressure system on the 02nd of April later strengthen into a Tropical depression 19F on the 4th as it progress Southeast near east of the island. However, an active cloud band associated with a convergence zone lies over the island which was also links to TD19F. All warnings and advisory were valid on the 04th of April afternoon (Wind advisory, Heavy rain warning & Small Craft advisory).
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 5 Maximum wind strength of (61kmph) 33knots was observed at the eastern side of Upolu and widespread rainfall recorded across the group (Lepiu: 169.5mm, Afimalu: 130.2mm &Nafanua: 115.4mm) Figure1.4.1: SMD Surface streamline analysis Figure 1.4.2: Enhance satellite image (d) TROPICAL CYCLONE ELLA(TD22F) (09/05/2017-12/05/2017) Tropical Disturbance 22F was upgraded and named tropical cyclone Ellaby RSMC Nadi on the 09th May 2017when it located approximately about 176km to the South of Samoa. However, TC Ella storm and gale force wind field diameter was too small, did not cause any damage over Samoa aside from rainfall activities. No special weather bulletin was issued except the heavy rain warning and small crafts advisory was enforced on the 9th May 2017. Surface observation depicted minimum impact from the aforementioned system where winds strengthen was below our strong wind advisory. Highest rainfall was recorded from Lepiu of 121mm/24hrs and the only station above 100mm/24hrs. Figure1.5.1: SMD Forecast Track. Figure:1.5.2: Himawari-8 products.
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 6 Figure1.5.3: ASCAT pass SAMOA TROPICAL CYCLONE SEASON NOVEMBER 2017 - APRIL 2018 2.2 INTRODUCTION Tropical Cyclone Gita was the only severe weather events to impact Samoa that occurred within 2017-2018 Tropical Cyclone Season and the only named system to enter Samoa Area of responsibility from six name Tropical cyclone which caused a lot of damages across the region. (a)tropical Disturbance 02F& TD03F (16/12/2017-19/12/2017) Two Tropical Disturbance (02F & 03F) was formed just southwest of Samoa and to the Northeast of Fiji Is, first TD02F on the 17th of Dec then TD03F on the 18th. Both system moved east-southeast near south of Samoa and dissipated further southeast, unfortunately a broad convective cloud located over the island produced gusty winds. Wind advisory, heavy rain warning and small crafts advisory was issued on the 17th of Dec 2018 and it was maintained until the 20th Dec 2017 Strong and gusty Northwest winds was observed from Faleolo airport and Apia station, recorded 56kmph(30knots) and 59.5kmph(32knots) with the highest rainfall of 88mm from Tiavi AWS station.
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 7 SAMOA Figure2.1.1: FMS Isobaric Analysis. Figure2.1.2: Himawari-8 product Figure2.1.3 ASCAT pass (b)tropical CYCLONE GITA (TD07F) (09/02/2018-11/02/2018) A tropical disturbance was identified on surface streamline analysis at 2:00PM local time Sunday 4th Feb. 2018. Its low level vortex (circulation) was evident on satellite imageries and surface observations; however structure was poor and disorganized convections around it. The system was slow moving and had the potential to develop into a tropical depression (TD) with numerical weather prediction (NWP) models indicating likely development into a tropical cyclone (TC). By 2:00AM local time Friday 9th Feb. 2018, the tropical disturbance developed into a Tropical Depression, then further intensified into a TC at 7:00PM of the same day and was named TC Gita by the Regional Specialized Meteorological Center (RSMC), Nadi Fiji Meteorological Services.
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 8 A total of seven special weather bulletin was issued where Samoa Tropical Cyclone Forecasting Warning Center (STCFWC) was activated on the 9th Feb 2018.First Special Weather Bulletin (SWB #1) was issued at 2:00pm on Friday 9th for Tropical Cyclone Warning Category 1 (39-54 mph) valid from 12-24 hours. Meanwhile, Wind Advisory was in force. TD07F remained unnamed at the time. TC Warning Cat 2 was enforced on Saturday 10th at 8.00am for Northern areas alone on the SWB#4. The final SWB was issued on Sunday 11th at 2:00am early morning where the system was moving further southeast of the island. Rainfall observation recorded the majority of all manual and AWS station ranges from 150mm to 250mm with the highest of 320mm from Le-Pue site at the eastern side of Upolu Is. Maximum winds was recorded from the Northern areas where Faleolo reached CAT 2 wind strengthen of 99.7kmph (53.8Knots) including Apia station of 98.2kmph (53.0Knots). Figure2.2.1: SMD TC GITA forecast track Figure2.2.2: ASCAT pass product Figure2.2.3: Himawari-8 Satellite image
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 9 2 Coordination with emergency managers and other stakeholders 1. Media briefing before the activation of the TC warning centre SMD present the current and forecast situation including a Question and Answer section. 2. Disaster Advisory Committee (DAC) : DAC comprised of all the heads of government ministries and organisations, private sector, Diplomatic Corp and development partners (confirmed the Day) including the core response agencies. SMD present the current and forecast situation including a Question and Answer section. 3. Disaster Advisory Council chaired by the Prime Minister (during and after TC Gita) Main presentation from SMD with collaboration with DMO Reports submitted to the National Emergency Operation Centre (NEOC) have detailed that the extent of damages caused by TC Gita are from flooding and strong winds. As of 2pm, Feb 10, the fifth Special Weather Bulletin issued by the SMD indicated that the TC category 2 warning (which was previously enforced for the Northern areas) was cancelled while the TC category 1 warning remains in force for all of Samoa. Updates from Response Agencies received by the NEOC include: The Electric Power Corporation reported on the restoration of electricity to Apia Urban areas. The Land Transport Authority continues to provide updates to NEOC as well as updating the general public through their Facebook page. They have been working to clear roads for major arterial routes and responding to calls as they have come in through emergency lines. Updates from the Samoa Tourism Authority for Savaii indicate medium damages to beach fales with major issues being no electricity, phone communication and no water supply in some areas; For Upolu in the town area - Sheraton guests have been evacuated to Sheraton Mulifanua, Tanoa and Hotel Insel Fehmarn. Evacuation shelters are located at the National University of Samoa (Vaivase), Latter Day Saints (Vaitoloa) and the Adventist Development and Relief Agency (ADRA) at Lalovaea. They are fully operational, taking in 244 people that have contacted NEOC for assistance. Also assisting to shelter evacuees from TC Gita is the residence of Vaasilifiti Moelagi Jackson. Food items for Evacuation shelters have been distributed - provided by the Government of Samoa. There have been no reports of any casualties as a result of Tropical Cyclone Gita. Response Agencies have been working together with the NEOC to facilitate all calls from the public and dispatching support where help is needed.
RA-V/TCC-17/Doc. x.x, DRAFT 1, p. 10