Seasonal Forecast for Spring 2020
(March to May 2020)
Assessment (as of 27 February 2020):
- In the past month or so, sea surface temperatures of the central and western equatorial Pacific were above normal despite a weak cooling. Based on the latest oceanic observations as well as forecasts by a number of climate models around the world, sea surface temperatures of the equatorial Pacific are expected to cool gradually in the next couple of months, returning to the normal level. Based on statistical analysis, the chance of normal to below-normal rainfall in Hong Kong in spring is slightly higher during ENSO-neutral conditions.
- 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 generally forecast weaker-than-normal northeast monsoon over southern China for this spring and hence normal to above-normal temperature over the region is expected.
- The majority of climate models around the world forecast normal to below-normal rainfall over the south China coast this spring, which is consistent with the forecasts given by objective statistical methods. Taking the above information and the development trend of sea surface temperature of the equatorial Pacific into consideration, the chance for normal to below-normal rainfall in Hong Kong this spring 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 2020 (June to August 2020) will be available around 1st June 2020.
Seasonal forecast charts provided by G-RCM and major climate centres: