Intense cold snap exposes Observatory shortcomings

I refer to the letters by Joseph Lee (“How did the Observatory get it wrong?”, January 27) and Bernard Lo (“Huge budget used to little apparent effect”, January 29) regarding the very cold weather on January 24.

We accept that the incorrect temperature forecast fell short of public expectations. Therefore, we have reviewed our weather operations and identified several areas for enhancement.

Concerning the lower temperature forecasts by certain overseas websites relative to the Observatory’s forecasts, we had explained through the media that they were not apple-to-apple comparisons mainly due to differences in the forecast location. I am not going to repeat the technical details here. Rather than relying on one computer model, the Observatory utilises several internationally recognised computer models and the state-of-the-art ensemble approach to generate our weather forecasts.

This provides the much-needed stability of the forecasts. Even though our long-term track record in temperature forecast accuracy has been one to two degrees Celsius, the ensemble approach failed in the present case. We will conduct research to seek improvements in our forecast techniques, especially for extreme weather.

The Observatory all along closely monitored the development of the intense cold surge. We alerted the public of very cold weather (temperatures at or below seven degrees) five days ahead through our weather bulletins and regular media interviews. On January 20, we stepped up communication through the Special Weather Tips to alert people of significant falling temperatures, high winds, icing and frost.

While all weather warnings were disseminated and a press conference was held a few days before, we take the point that the warnings could have been even more effective with the inclusion of more impact-based advisory messages, for example, wind chill effects of low temperatures and high winds, and slippery roads as a result of icing and freezing rain.

We will try to improve communication should such weather events recur.

We will aim to enhance our services to meet public expectations and increase society’s awareness of extreme weather events and disaster preparedness through public outreach, not only for typhoons and heavy rain but also in the rare event of wintry weather, with the lessons learned from this intense cold surge.

Lee Lap-shun, senior scientific officer, Hong Kong Observatory