HK typhoon forecast: too early to tell, experts warn

Conflicting weather models have sparked speculation about a potential tropical cyclone approaching Hong Kong next week. However, meteorological experts are cautioning that predictions beyond five days remain highly uncertain.

The diverging forecasts

Initial projections by the US Global Forecast System (GFS) on May 19 suggested that a significant tropical system could form in the South China Sea, taking a sharp turn toward Guangdong and coming closest to Hong Kong around May 30, potentially making landfall near Shanwei.

However, updated GFS data on May 20 indicated a markedly weaker system, with its strongest winds concentrated south of Hong Kong before possibly veering toward Taiwan by June 1. Notably, other major forecasting bodies, including the European Centre for Medium-Range Weather Forecasts (ECMWF) and Germany's ICON model, do not show similar development.

Experts urge caution

Leung Wing-mo, former Assistant Director of the Observatory and now with the Hong Kong Meteorological Society, highlighted the limitations of long-range forecasting. He explained that predictions beyond ten days could have errors spanning hundreds of kilometers and questioned whether a storm would even materialize. He compared weather systems to the "butterfly effect," where minor initial variations lead to vastly different outcomes.

Shun Chi-ming, former Observatory Chief, expressed that it is highly inadvisable to predict cyclones ten days in advance. He noted that official forecasts worldwide typically only project tropical cyclones five to seven days out, with a potential margin of error of 400-600km.

Hong Kong's typhoon season outlook

The Observatory's forecast in March indicated that the typhoon season may begin in June or earlier, ending in October or later, with five to eight tropical cyclones entering Hong Kong's 500km radius—this is considered normal to slightly above average. While May storms like last year's Tropical Storm Maliksi do occur, they remain relatively rare.

A warning against clickbait

Both experts criticized the practice of sensationalized weather reporting. Shun pointed out that if platforms prioritize clicks by exaggerating storm threats, informed citizens are likely to dismiss such reports. Leung advised residents to monitor updates but cautioned against overreacting to early projections, noting that typhoon enthusiasts often end up disappointed.

The observatory maintains its standard advisory: Stay alert to official updates, especially as the South China Sea enters its more active storm period from June onward.