Impact-based forecasts and risk-based warnings are the key approach to reduce disasters caused by tropical cyclones (TCs). This review paper highlights Japan Meteorological Agency’s and RSMC Tokyo – Typhoon Center’s development and efforts to operationalization of various TC observation, analysis and numerical weather prediction (NWP) techniques, which are the fundamental basis of the approach.   TC monitoring has been carried out with geostationary satellites named Himawari series since 1978. Since 2015 the first new generation satellite Himawari-8 has established new era of the TC monitoring at a high resolution and frequency. In addition, space-borne microwave instruments have provided many hydrological properties around TC.   As for ground based observation, radar is a powerful tool to investigate the TC structure characterized by rain distribution and wind fields. A phased-array radar gives us the vivid pictures of individual cumulonimbus with its quick scan ability. RSMC-Tokyo uses the Himawari-8/9 images, atmospheric motion vectors (AMVs), space-borne microwave images, sea surface winds of scatterometer, and ground-based radar wind observation for the TC intensity analysis.   For NWP, many efforts have been put into new assimilation schemes, high-resolution models and combined atmosphere-ocean models. Ensemble based analysis and forecast system are considered to be effective to estimate the uncertainty of the TC forecasts.

Hurricanes Harvey and Irma had a huge impact on the Southern United States and in the case of Irma, also parts of the Caribbean Islands. Here we focus on the impact of both hurricanes following a period of rapid intensification. The structure of hurricanes were examined using wind data made available from aircraft
reconnaissance missions. Intense convection developed in a region where the winds in the lower to middle levels turned anticyclonically with height. Earlier studies showed that this wind structure was similar to that would be found in an ascent region theoretically associated with Quasi-Geostrophic warm air advection.

  The tropical cyclone (TC) named Amos (2016) that impacted the Samoan Islands on 23 April 2016 was a particularly difficult storm to forecast. Both the intensity changes and the track of Amos represent a significant challenge for forecasters and this is briefly summarized in this report.
  Model forecasts initially indicated that the cyclone would track south of the Samoan Islands. However, the forecasts generally changed to a direct hit over Samoa as a Category 4 storm at approximately 0000 UTC 24 April based on model cycles initialized at 0000 UTC 23 April.
  TC Amos’ central pressure dropped from 983 hPa to 957 hPa between 0000 UTC 21 April and 0000 UTC 23 April. The models did not pick up on this rapid intensification until the intensification had already begun around 0000 UTC 21 April. The models also struggled to capture the rapid weakening of TC Amos due to vertical wind shear that began 0000 UTC 24 April as the cyclone continued to move north of the islands.
  Because of the initially ominous track forecasts for TC Amos to hit land, preparations for a Category 3 or Category 4 cyclone were underway in the Samoan islands and the population prepared for the worst. After the center of the storm moved north of the islands as a weaker storm than anticipated, the residents of the Samoan Islands were both surprised and relieved that the cyclone only gave a “glancing blow” to the islands and that the impacts were not as bad as originally feared. An in-depth evaluation of this particular tropical cyclone helps to shed some light on model deficiencies and can be used to help determine future model changes.

Understanding impacts of typhoons due to storm surge plays an important role in reducing damage in coastal areas. This study used the SWAN wave model to simulate the typhoon waves and the SuWAT model to simulate storm surge and inundation caused by Typhoon Xangsane in 2006 which landed in the Central Coast of Vietnam from Nghe An to Phu Yen Provinces. The wind-pressure field was calculated by the Fujita’s model and reanalysis data were inputted to the SWAN and SuWAT models. The simulated results of the typhoon wave showed that Typhoon Xangsane caused 5-7 m height waves in the coastal areas with a radius of 600 km. The results of the storm surge combined with the simulations of wind, pressure, wave, and tide in the coastal areas were estimated at 2 m. The simulated and calculated results of storm surge and inundation maps will help the decision makers in the Committee for Natural Disaster Prevention and Control to reduce the impacts of natural disasters induced to storm surge in the near future.

The main objective of this paper is to present the current status of the improvement technology for tropical cyclones alerting and warning in Thailand. In 2017, Thai Meteorological Department upgraded Weather Forecasting system with Geogrid data for TMD domain with a High Performance Computer. The use of Himawari satellite data with receiving and analysis facilities provided by the Japan Government leads to timely monitoring of tropical storm events. The Typhoon Committee’s project on the network of weather radar plays supporting roles in storms’ analysis and their impacts. Currently, TMD actively makes use of internet social-media, including Google Map and Facebook as an alternative to release information to the public.