AGENDA ITEM 2.1: OPERATIONAL FORECASTS/ADVISORIES, WATCHES AND WARNINGS - REQUIREMENTS

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1 World Meteorological Organization TROPICAL CYCLONE RSMCS/TCWCS TECHNICAL COORDINATION MEETING Ninth Session Honolulu, Hawaii, USA, 9 to 12 December 2018 TCM-9/DOC.2.1.1/4 Submitted by: TCWC Wellington 5.XII.2018 AGENDA ITEM 2.: FOLLOW-UP ACTIONS ON THE TCM-8 AGENDA ITEM 2.1: OPERATIONAL FORECASTS/ADVISORIES, WATCHES AND WARNINGS - REQUIREMENTS AGENDA ITEM 2.1.1: RECENT AND CURRENT ACTIVITIES OF THE RSMCS AND TCWCS AGENDA ITEM 2.1.1/4: RECENT AND CURRENT ACTIVITIES OF THE TCWC WELLINGTON 1. Introduction TCWC Wellington (operated by Meteorological Service of New Zealand Ltd, or MetService) is responsible for issuing forecasts and warnings on tropical cyclones and/or reclassified cyclones over the ocean area from 160E to 120W between 25S and 40S, the Wellington area of responsibility (AOR), also for the coastal waters and land areas of New Zealand. The TCWC role is carried out by RSMC Wellington 1 Lead and Tropical meteorologists who also produce guidance for the Severe Weather Forecasting and Disaster risk reduction Demonstration Project (SWFDDP) in the South Pacific. The region covered by the project is from 150E to 150W between 5N and 25S, with 9 countries participating; Cook Islands, Fiji, Kiribati, Niue, Samoa, Solomon Islands, Tuvalu, Tonga and Vanuatu Operational Activities and Coordination 2.1 Season Summaries /16 Season During the 2015/16 cyclone season, set against a very strong El Niño that weakened late season, a total of four of the eight named tropical cyclones in the South Pacific and Coral Sea basins exited the tropics into the Wellington AOR as either a named or significant reclassified tropical cyclone (TC s Ula, Victor, Winston and Tatiana). Winston was the most destructive and deadly cyclone in the South Pacific during the season (and the most intense in the Southern Hemisphere on record) and took an unusual track, dipping below 25S into the Wellington AOR before moving north again back into the Nadi AOR (only the second time on record this has occurred after TC Jasmine in 2012). Winston finally moved into the Wellington AOR as a category 1 cyclone, while the most intense to cross the boundary was Ula as a category 3 severe tropical cyclone. Victor was the most impactful on New Zealand, bringing heavy rain and strong winds to the east of the North Island. 1 MetService has designation as a Regional Specialised Meteorological Centre (RSMC) with specialised activities for Marine Meteorological Services and for Regional Severe Weather Forecasting 2 See the WMO SDFDDP-SP page for more information

2 TCM-9/DOC.2.1.1/4, p. 2 Figure 1. Cumulative track map for cyclones that moved into the Wellington AOR during the 2015/16 season. Positions plotted are a blend of RSMC Nadi and TCWC Brisbane operational tracks (north of 25S) and TCWC Wellington verification tracks (south of 25S) /17 Season During the 2016/17 cyclone season, set against a neutral ENSO phase trending from a weak La Niña to a weak El Niño bias during the season, a total of three of the five named cyclones in the South Pacific and Coral Sea basins moved into the Wellington AOR (TC s Bart, Cook and Donna). While Donna was the most intense in the Nadi AOR (reaching category 5 the strongest out-of-season cyclone in the month of May), Cook was the strongest cyclone to move into the Wellington AOR during the season as a category 2 cyclone. Both Cook and Donna impacted the North Island of New Zealand directly with heavy rain and strong winds in the northeast and north respectively.

3 TCM-9/DOC.2.1.1/4, p. 3 Figure 2. Cumulative track map for cyclones that moved into the Wellington AOR during the 2016/17 season. Positions plotted are a blend of RSMC Nadi operational tracks (north of 25S) and TCWC Wellington verification tracks (south of 25S) /18 Season During the 2017/18 cyclone season, set against a weak La Niña to neutral ENSO phase, a total of four of the seven named cyclones in the South Pacific and Coral Sea basins moved into the Wellington AOR (TC s Fehi, Gita, Hola and Keni). Gita was the most intense TC in the Nadi AOR this season (reaching category 5) and along with Keni, was a category 3 severe tropical cyclone on arrival in the Wellington AOR. Fehi and Gita both impacted New Zealand significantly, with coastal inundation and flooding a common theme (along with heavy rain and strong winds), while Hola passed offshore to the northeast of the country after earlier concerns for a direct impact on the North Island.

4 TCM-9/DOC.2.1.1/4, p. 4 Figure 3. Cumulative track map for cyclones that moved into the Wellington area during the 2017/18 season. Positions plotted are a blend of RSMC Nadi operational tracks (north of 25S) and TCWC Wellington verification tracks (south of 25S). 2.2 Coordination with RSMC Nadi In advance of every tropical cyclone passing from the Nadi AOR into the Wellington AOR, RSMC Nadi and TCWC Wellington liaise closely to coordinate a formal handover for warning responsibility, ensuring this is clearly referenced in the final warning issued by RSMC Nadi in their AOR. At the time of handover, RSMC Nadi shares its Tropical Cyclone Analysis Worksheet with TCWC Wellington to ensure consistency both in the application of the Dvorak technique and in the statement of intensity. These procedures were carried out successfully for all cyclones crossing the Nadi/Wellington boundary during the 2015/16, 2016/17 and 2017/18 seasons. Besides these operational arrangements for cyclone/warning handover, TCWC Wellington also has formal backup obligations for RSMC Nadi as detailed in the Tropical Cyclone Operational Plan for the South Pacific and South-East Indian Ocean (WMO-1181/TCP-24 via WMO website). For cyclones that may directly impact Fiji and have the potential to disrupt communications, TCWC Wellington invokes a check-bulletin procedure to closely monitor and confirm working communications to/from Fiji. Under this procedure, GTS messages are transmitted every 30 minutes by RSMC Nadi, and immediately acknowledged by TCWC Wellington. Failure of any check message to arrive triggers further communication checks, while failure of three consecutive check messages coupled with no other available communications with Fiji triggers full backup procedures for TCWC Wellington to assume RSMC Nadi responsibilities as described in the Operational Plan. This check-bulletin procedure was activated twice in recent seasons;

5 TCM-9/DOC.2.1.1/4, p. 5 ahead of TC Winston s passage over Fiji in Feb 2016 and for TC Keni in Apr On both occasions, communications were not impacted and no further backup steps were necessary. 2.3 Boundary Realignment On 12 December 2017, a realignment of the high seas forecast and warning boundary between Australia and New Zealand came into effect. The realignment resulted in the removal of an overlap in services from the Bureau of Meteorology (Australia) and MetService (New Zealand), with the new boundary for services aligned to the METAREA boundary between regions X and XIV. See this joint Information Sheet from the Bureau of Meteorology and MetService for further details from which the following figure is taken; Figure 4. New High Seas forecast and warning boundaries between METAREA X and XIV. However, while the boundary realignment was implemented for high seas forecasts and warnings, it did not formally apply to TC Warnings and RSMC/TCWC boundaries as specified in the Tropical Cyclone Operational Plan for the South Pacific and South-East Indian Ocean (WMO-1181/TCP-24). As a result, there is currently an overlap area between the TCWC Wellington AOR and METAREA X in which warnings may come from one of two agencies depending on whether the warning is for a Tropical Cyclone or not (ie for a system south of 25S the warning will come from New Zealand for a TC, but from Australia for a non-tc). Additionally, while a TC Warning will come from New Zealand in this overlap area, the High Seas forecast will come from Australia.

6 TCM-9/DOC.2.1.1/4, p. 6 The new boundaries were put to the test twice in the 2017/18 Cyclone Season, as both Fehi and Gita transited through the overlap area between TCWC Wellington and METAREA X. Fehi, in particular, was a challenge as the system was reclassified on the boundary necessitating a double handover for warning responsibility. Fiji handed TC warning responsibility to New Zealand, but as the system was immediately reclassified, warning responsibility on the ex-tc transferred to Australia. While these boundaries and overlap may create a challenge at the operational level between forecast offices in New Zealand, Australia and Fiji, the Operational Plan already has provisions in place to address systems near or transiting boundaries that are relevant; see sections (One comprehensive marine warning per cyclone), (Warnings near common boundaries) or (Transfer of warning responsibilities). Effective communication between forecast offices will continue to ensure smooth provision of forecast/warning services. 2.4 Operational Track Verification Verifications of analysis and 12/24 hour forecast positions for the 2016/17 and 2017/18 season show an increase in the five-year moving average of the mean error during the last two seasons. This increase is largely due to a spike in the 2016/17 season related to poor forecast performance for TC Bart (with just three analysis positions in the Wellington AOR). By comparison, mean errors for TC Cook in the same season were 20/92/83km for the analysis/12/24h positions. Figure 5. Graph of TCWC Wellington mean position errors for the analysis (H+00) and forecast (H+12 and H+24) position in operational TC warnings for the high seas. The 16-year period above includes 47 cyclones and 165 analysis (H+00) positions.

7 TCM-9/DOC.2.1.1/4, p Products 3.1 GTS Bulletins The following GTS bulletins are issued routinely and/or as required for the Wellington AOR; FQPS43 NZKL Marine High Seas Forecast for Subtropic Area FQPS45 NZKL Marine High Seas Forecast for Pacific Area WWNZ40 NZKL Marine High Seas Gale / Storm Warning (non-tc) WTNZ41 NZKL Marine Tropical Cyclone Gale / Storm Warning WHNZ41 NZKL Marine Tropical Cyclone Hurricane Warning WCPS21 NZKL Aviation SIGMET for Tropical Cyclone in NZZO Area 3.2 Other Products / Services Tropical Cyclone Season Outlook Ahead of the Southern Hemisphere TC Season, MetService works alongside New Zealand s National Institute of Water & Atmospheric Research (NIWA), Australia s Bureau of Meteorology and national meteorological services from other Pacific nations to produce a Tropical Cyclone Outlook in October for the coming season. This is published in full on the NIWA website, with key messages distributed via social media and in press releases.

8 TCM-9/DOC.2.1.1/4, p. 8 Figure 6. Example of TC Season Outlook key messages shared on social media by MetService Tropical Cyclone Potential Bulletin The Tropical Cyclone Potential (TCP) Bulletin is designed to provide information on current and developing cyclones in the South Pacific and Coral Sea in the next few days. The potential for formation of each disturbance in the forecast period is stated as low, moderate or high relating to one, two or three chances in five respectively. The TCP Bulletin is issued daily around 0330 UTC during the tropical cyclone season, between 1 November and 30 April, and at other times if a tropical disturbance shows signs of development into a tropical cyclone. The Bulletin is published on the Tropical Cyclone Activity page of the MetService website and includes three sections; 1. Current status of cyclone activity 2. Forecast until 1200 UTC tomorrow 3. Outlook for the following three days Track Map For tropical systems expected to impact New Zealand, TCWC Wellington publishes a TC Track Map, also available via the MetService Tropical Cyclone Activity page.

9 TCM-9/DOC.2.1.1/4, p. 9 Figure 7. Example TC Track Map for Cyclone Gita as it crossed into the Wellington AOR, valid at 0600 UTC 17 February Streamline Analysis A hybrid streamline/synoptic chart is published at least daily depicting streamlines north of 25S and isobars/fronts south of 25S, also available via the MetService Tropical Cyclone Activity page.

10 TCM-9/DOC.2.1.1/4, p. 10 Figure 8. Example hybrid streamline/synoptic chart, valid 0000 UTC 4 December South Pacific Guidance via SWFDDP As part of the Severe Weather Forecasting and Disaster risk reduction Demonstration Project (SWFDDP), RSMC Wellington produces (twice a day) a five-day outlook known as the South Pacific Guidance (SPG). Five charts and associated situation statements comprise the SPG and are valid for one day each, the purpose of which is to provide the participating Pacific NMCs with a heads up of potential hazardous weather. These charts (such as the example below) contain references to existing and potential tropical cyclone activity, as well information about non-tc heavy rain, strong winds and large waves 3. They also highlight any interesting cyclonic areas beyond that covered by the RSMC Nadi TC Outlook. The SPG charts (along with other global NWP products and observations) are made available on MetConnect Pacific, the SWFDDP password protected website. 3 Thresholds are; heavy rain 100mm / 24hr, strong wind 30kt, large waves 2.5m north of 15S and 3.5m south of 15S, and tropical cyclones now or later

11 TCM-9/DOC.2.1.1/4, p. 11 Figure 9. Example SPG chart via the SWFDDP website, valid 1200 UTC 10 February RSMC Nadi Backup TCWC Wellington has formal backup obligations for RSMC Nadi as detailed in the Tropical Cyclone Operational Plan for the South Pacific and South-East Indian Ocean (WMO-1181/TCP- 24). As specified in the Plan, products covered are; Tropical Cyclone High Seas Warnings Special Weather Bulletin for Cook Islands, Fiji, Kiribati, Nauru, Niue, Tokelau and Tuvalu Tropical Disturbance Advisories Additionally; High seas forecasts and warnings for MetArea XIV and MetArea X for which RSMC Nadi has agreed to act as a Preparation Service and as documented in the WMO Manual on Marine Meteorological Services (No. 558). Aviation advisory information for tropical cyclones as required by an ICAO designated Tropical Cyclone Advisory Centre as documented in Annex 3 to the Convention on International Civil Aviation (reproduced as WMO-No. 49, Technical Regulations, Volume II, Meteorological Service for International Air Navigation).

12 TCM-9/DOC.2.1.1/4, p. 12 SIGMETs for tropical cyclones in the Nadi FIR area 4. Training and Participation 4.1 TCWC Wellington Training Training courses are run annually at MetService ahead of each cyclone season. In particular; Full-day tropical workshops for all RSMC Wellington Lead, Marine and TCWC meteorologists involved in the tropical cyclone forecast process Two half-day pre-season training sessions for Ministry of Foreign Affairs and Trade staff who, through their Pacific Division, work with the inter-agency Emergency Task Force whose role it is to consider, plan and manage the New Zealand disaster response in the South Pacific 4.2 International Participation Involvement in TC related international training courses or meetings during the TCM intersessional period has included; 16 th Session of the RA V Tropical Cyclone Committee for the South Pacific and Southeast Indian Ocean (TCC-16), 29 Aug 2 Sep 2016, Honiara, Solomon Islands attended by Chris Noble 12 th RA V Southern Hemisphere Training Course on Tropical Cyclones, Sep 2017, Nadi, Fiji attended by Miroslav Malivuk 8 th RA I Training Course on Tropical Cyclones and Public Weather Services PWS portion from Sep 2017, La Reunion, attended and co-facilitated by Chris Noble RA V Working Group Leads' and TCC Chair's Meeting, Nov 2017, Jakarta, Indonesia attended by Chris Noble on behalf of TCC Chair Mike Bergin 17 th Session of the RA V Tropical Cyclone Committee for the South Pacific and Southeast Indian Ocean (TCC-17), July 2018, Nouméa, New Caledonia attended by Chris Noble 7 th Regional Conference on Management of National Meteorological and Hydrological Services (RECO-7) in RA V, October 2018, Nuku alofa, Tonga attended by Chris Noble on behalf of TCC Chair Mike Bergin 9 th International Workshop on Tropical Cyclones (IWTC-9), 3-7 December 2018, Honolulu, Hawaii, USA attended by Matthew Ford