Assessment (as of 28 February 2018):
- In the past month or so, sea surface temperatures of the central and eastern equatorial Pacific remained below normal. Based on the latest oceanic observations as well as forecasts by a number of climate models around the world, sea surface temperatures of the central and eastern equatorial Pacific are expected to warm gradually in the next few months.
- Under the influence of global warming and local urbanization, spring temperatures in Hong Kong exhibit a significant long-term rising trend. Climate models around the world also forecast normal to above-normal temperatures over southern China this spring.
- Climate models around the world generally forecast that the rainfall over southern China this spring would be normal to below normal. The chance for normal to below-normal spring rainfall in Hong Kong in 2018 is expected to be slightly higher.
- 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 2018 (June to August 2018) will be available around 1st June 2018.
Seasonal forecast charts provided by G-RCM and major climate centres: