Met Office Cyclone account

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PR - The purpose of this article is to provide a comprehensive account of the operation and monitoring of Tropical Cyclone Amos by the Meteorology Division (MD) of the Ministry of Natural Resources and Environment (MNRE) for information, and to clarify some of the public misunderstandings.

The Meteorology Division (MD) of the Ministry of Natural Resources and Environment is the official government agency responsible for dealing with all matters related to meteorology in Samoa. MD also has the responsibility for providing quality data and warning information for Earthquake, Tsunami, Volcano, tides and oceans, climate and weather in Samoa.  Recipients of such data and information are the general public, the office of DMO, Disaster Advisory Council, Media, private and other government sectors.

 MD is also the designated meteorological authority in Samoa for providing weather service for international air navigation in accordance with the rules and regulations of International Civil Aviation Organization (ICAO) and the Civil Aviation Division of the Ministry of Works, Transport and Infrastructure, Samoa.

Gathering of Weather Information for TC Amos

MD is receiving in real-time (every 15 minutes) all of its land-based or surface weather information (referred to as observations from a network of 24 automatic weather stations dotted around Savaii and Upolu, all of these stations were working during TC Amos).

Remote-sensing technology (outer space view), commonly referred to as satellite imageries, MD are receiving them every thirty minutes from the latest Japanese satellite Himawari - 8 feeding through the internet, the only one of its kind in Samoa, the best and highest resolution capability. Just to stress that even with this highly defined resolution, estimates of rainfall quantities and wind strengths posed a greater degree of uncertainty. In order to improve the degree of accuracy it is essential to operate on Radar technology (Doppler radar). Hence, MD is requesting government to deploy a Doppler Radar to greatly improve our current crude estimates.  

Further, MD has a Wind-Profiler Radar to provide weather information (winds, rainfall, temperatures) at different levels (vertical profiles) of the atmosphere to determine indices (forecast) for these parameters. 

Although the notion of an hourly-update is correct for satellite imageries, it is not good practice as this leads to inaccuracy of TC positions, as composite products is essential for accuracy. Also this leaves insufficient time for centers to carry out the analysis/processing/compilation time for products from global, regional and national centers, which requires at least 3 hours of time. 

MD Standard Operating Procedure (SOP), for Warnings from Wind Advisory to a Tropical Storm (Cat. 1 or 2) is provided every 6 hours and Severe Tropical Cyclone (> Cat.3) is provided every 3 hours issue time, these time-frames are internationally accepted rules practiced by all meteorological centers.   

Aligning Meteorology to International and national Protocols and first prediction

MD is a member of the World Meterological Organisation and other international and national agreements in the handling of meteorology matters such as Tropical Cyclone Amos.

On Wednesday 20th April 2016 at a 3:00 p.m. meeting, ACEO and Forecaster of MD gave a briefing to the Chief Executive Officer of the Ministry on the potential of TD017F (tropical disturbance) brewing to the north-east of the Fiji islands to develop into a tropical cyclone from a consensus view with the Fiji Meteorological Service, Regional Specialized Meteorological Center (RSMC) in Nadi. 

After this briefing with MNRE CEO the MD was advised to call a Media Briefing the following day, Thursday 21st April 2016, which was held at 11:00 p.m. at the MD’s conference room. At this briefing, MD had an initial prediction for a land-fall, Saturday 23rd April evening towards the morning of Sunday 24th April 2016, this matched with our first issue in Special Weather Bulletin 1. TC Cat.2 Warning at 7:00 p.m. will be effective in the next 36 to 48 hours, if translated to days after the end of 48 hours is Saturday evening.

The forecast track at the time in collaboration with global and regional center in ensemble (combined of 50 models) takes TC Amos south of the country. It was clear also at the media briefing MD made a possible track to the north of Samoa because of the ‘warm pool’ a favorable ingredient or ‘food’ to fuel this system (TC Amos). The Disaster Advisory Council (DAC) was called and the meeting was held on Friday 22nd April 2016 at 1:00 p.m., and again MD made a presentation with similar predictions made at the media briefing the previous day. 

In addition to adhere to international agreements this included our partner the Fiji RSMC which is the only regional center tasked with the naming of a system under all conditions, even if other centers, including Samoa have identical analysis and view, the reason for MD’s reservations sometimes to name it. So it follows why TD017 was named by Fiji RSMC Nadi as TC Amos with condition warrant for a Cat. 1 at 1:00 a.m. when it was located 795 km west of Asau Savaii.

Further on Thursday 21st at 1:00 p.m. MD National Tropical Cyclone Warning Center (NTCWC) was activated and its first Special Weather Bulletin 1 was issue at 7:00 p.m. (SWB 1), Cat. 2 Warning to be effective in the next 36 to 48 hours (after 48 hours, 7:00 p.m. Saturday it shall be effective). 

Time Fiji RSMC of Category 3 and Category 4 forecasts for TC Amos, (be mindful that these are forecasts not actual observations)

Cat 3 (issue time Friday 7:00 p.m.) forecast position: 7:00 p.m. Saturday 23rd ;

Cat 4 (issue time Saturday 1:00 a.m.) forecast position: 1:00 a.m. Sunday morning

Although Fiji issued forecasts for Category 3 and Category 4 we had still maintained a warning at Category 2 until the end of TC Amos operations because our observations showed otherwise. 

MD would also like to clarify the issue of Cat. 3 in Special Weather Bulletin 10, when it stated TC Cat.3 will be effective in the next 6-18 hours (Sunday 7:00 p.m.) evening after 18 hours, this was just a forecast if the situation warrants then we will have to upgrade the warning. In saying the above the category TC Cat. 3 was never in effect for the remaining time of TC Amos operation.    

Performance and valid information from Special Weather Bulletins (SWB) – total of 12 Special Weather Bulletins were issued during the operation of TC Amos

(Highlighted in red is the effective time of TC Cat. 2 (SWB 8) and cancellation (SWB 12) 

Thursday 21st @ 7:00 p.m. SWB 1: Tropical Cyclone Warning Cat.2 will be effective for Samoa (in the next 36 – 48) hours – Heavy Rain warning, Coastal flood advisory, and Small Crafts Advisory all in effect;

Friday 22nd @ 1:00 a.m. SWB 2: Tropical Cyclone Warning Cat.2 will be effective for Samoa (in the next 24 – 36) hours – Wind Advisory Heavy Rain warning, Coastal flood advisory, and Small Crafts Advisory all in effect;

Friday 22nd @ 7:00 a.m. SWB 3: Tropical Cyclone Warning Cat.2 will be effective for Samoa (in the next 24 – 36) hours – Wind Advisory Heavy Rain warning, Coastal flood advisory, and Small Crafts Advisory all in effect;

Friday 22nd @ 1:00 p.m. SWB 4: Tropical Cyclone Warning Cat.2 will be effective for Samoa (in the next 24 – 36) hours – Wind Advisory Heavy Rain warning, Coastal flood advisory, and Small Crafts Advisory all in effect;

Friday 22nd @ 7:00 p.m. SWB 5: Tropical Cyclone Warning Cat.2 will be effective for Samoa (in the next 12 – 24) hours – Wind Advisory Heavy Rain warning, Coastal flood advisory, and Small Crafts Advisory all in effect;

Saturday 23rd @ 1:00 a.m. SWB 6: Tropical Cyclone Warning Cat.2 will be effective for Samoa (in the next 6 – 12) hours – Wind Advisory Heavy Rain warning, Coastal flood advisory, and Small Crafts Advisory all in effect;

Saturday 23rd @ 7:00 a.m. SWB 7: Tropical Cyclone Warning Cat.2 will be effective for Samoa (in the next 6) hours – Wind Advisory Heavy Rain warning, Coastal flood advisory, and Small Crafts Advisory all in effect;

Saturday 23rd @ 1:00 p.m. SWB 8: Tropical Cyclone Warning Cat.2 is in effect, Heavy Rain warning, Coastal flood advisory;

Saturday 23rd @ 7:00 p.m. SWB 9: Tropical Cyclone Warning Cat.2  remains in effect- Rain warning, Coastal flood advisory,

Tropical Cyclone Warning Cat.3 will be effective for Samoa (in the next 6-18) hours;

Sunday 24th @ 1:00 a.m. SWB 10: Tropical Cyclone Warning Cat.2 remains in effect, Heavy Rain warning, Coastal flood advisory

Tropical Cyclone Warning Cat.3 will be effective for Samoa (in the next 6-18) hours -;

Sunday 24th @ 7:00 a.m. SWB 11: Tropical Cyclone Warning Cat.2 Cancelled for Samoa- Tropical Cyclone Warning Cat.1 (Eastern side), Heavy Rain warning, Coastal flood advisory;

Sunday 24th @ 1:00 p.m. SWB 12: Tropical Cyclone Warning Cancelled for Samoa- , Heavy Rain warning for east side of Upolu, Coastal flood advisory;

MD also notes that all the issues raised by the public that challenges the operation of TC Amos probed up post-TC Amos. The hope is that these issues were raised earlier when ‘forecasts’ were just the means of operation, and would had welcome justifiable comments to improve our services.  

Lastly, MD acknowledges and are most grateful to the government agencies involved, all the media outlets and DAC members for the support given. MD will always strive for the most effective services to ensure the safety of lives and protection of properties for the people of Samoa.   

© Samoa Observer 2016

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