The Hong Kong Observatory will start to issue seasonal forecasts of average temperature and total rainfall, which will be expressed in terms of "above normal," "near normal" and "below normal," the Observatory said Tuesday.

The forecasts will be issued in March, June, September and December through the government website, the Observatory's Assistant Director Yeung said at a media briefing.

Yeung said seasonal forecasts refer to forecasts of the average weather in the coming month, year, or season. For instance, a forecast could be for a warmer than average summer, or a colder than average winter.

"These forecasts are useful for planning activities which are influenced by the weather or the climate. They can be used to assess the demand for soft drinks in the summer or for warm clothing in the winter, and to adjust the production or inventory levels accordingly. The Chicago Mercantile Exchange in the United States even offers weather futures," Yeung said.

The primary tool for producing the forecasts is a regional climate model adapted from the Experimental Climate Prediction Center of the University of California at San Diego. Model-generated forecast maps will also be displayed on the website.

Outputs of climate models from other climate centers will be taken into consideration in formulating the seasonal forecasts.

Yeung explained with the present state of technology, the accuracy of climate models is not yet as good as that of numerical weather-prediction models.

"That is why the Observatory is only issuing the seasonal forecasts on an experimental basis. This will be included as part of the regular forecasting service later when the technology has gained more maturity," Yeung said, adding this is the practice other climate centers adopt.

(Xinhua News Agency February 8, 2006)