Nowcast guidance of afternoon convection initiation for Taiwan

Hui Ling Chang, Barbara G. Brown, Pao Shin Chu, Yu Chieng Liou, Wen Ho Wang

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Focusing on afternoon thunderstorms in Taiwan during the warm season (May-October) under weak synoptic forcing, this study applied the Taiwan Auto-NowCaster (TANC) to produce 1-h likelihood nowcasts of afternoon convection initiation (ACI) using a fuzzy logic approach. The primary objective is to design more useful forecast products with uncertainty regions of predicted thunderstorms to provide nowcast guidance of ACI for forecasters. Four sensitivity tests on forecast performance were conducted to improve the usefulness of nowcasts for forecasters. The optimal likelihood threshold (Lt) for ACIs, which is the likelihood value that best corresponds to the observed ACIs, was determined to be 0.6. Because of the high uncertainty on the exact location or timing of ACIs in nowcasts, location displacement and temporal shifting of ACIs should be considered in operational applications. When a spatial window of 5 km and a temporal window of 18 min are applied, the TANC displays moderate accuracy and satisfactory discrimination with an acceptable degree of overforecasting. The nonparametric Mann-Whitney test indicated that the performance of the TANC substantially surpasses the competing Space and Time Multiscale Analysis System-Weather Research and Forecasting Model, which serves as a pertinent reference for short-range (0-6 h) forecasts at the Central Weather Bureau in Taiwan.

Original languageEnglish
Pages (from-to)1801-1817
Number of pages17
JournalWeather and Forecasting
Volume32
Issue number5
DOIs
StatePublished - 1 Oct 2017

Keywords

  • Ensembles
  • Forecast verification/skill
  • Forecasting techniques
  • Nowcasting
  • Operational forecasting
  • Probability forecasts/models/distribution

Fingerprint

Dive into the research topics of 'Nowcast guidance of afternoon convection initiation for Taiwan'. Together they form a unique fingerprint.

Cite this