Assessment (as of 28 February 2019):
- Sea surface temperatures of the central and eastern equatorial Pacific have been above normal for the past few months. Based on the latest oceanic observations as well as forecasts by a number of climate models around the world, El Niño is likely to become established shortly. According to statistical analysis, the chance of normal to above-normal temperature in Hong Kong in spring is slightly higher during El Niño while the chance of normal to above-normal spring rainfall in Hong Kong is higher.
- Besides, under the influence of global warming and local urbanization, spring temperatures in Hong Kong exhibit a significant long-term rising trend. The chance of normal to above-normal temperature is generally higher. Climate models around the world forecast weaker-than-normal northeast monsoon over southern China this spring and hence normal to above-normal temperature over the region is expected.
- In spring, El Niño affects the atmospheric circulation over the northern part of the South China Sea, bringing generally more rainfall to the coastal region as compared to the ENSO-neutral state. Climate models around the world also forecast similar circulation pattern for this spring, consistent with the situation during El Niño.
- Climate prediction centres around the world generate seasonal forecasts, employing a variety of methods including
dynamical models, statistical methods, expert judgment and combinations of them. Predictions from different centres do
not always agree and large discrepancies can occur at times. The Observatory adopts an ensemble approach to formulate
its seasonal forecast for Hong Kong, taking into consideration available products from major climate prediction centres
and the Global-Regional Climate Model (G-RCM) operated in house. Thus,
the resulting forecast issued by the Observatory may be different from the forecast given by G-RCM.
- The Observatory gratefully acknowledges the Tokyo Climate Center of the Japan Meteorological Agency and the National
Centers for Environmental Prediction of National Oceanic and Atmospheric Administration, USA for providing dynamical
prediction model forecast and hindcast data to support the formulation of seasonal forecast for Hong Kong.
- Forecast for summer 2019 (June to August 2019) will be available around 1st
Seasonal forecast charts provided by G-RCM and major climate centres: