The Hong Kong Observatory will issue the gale or storm signal No 8 at 2:20 pm on Tuesday, as Super Typhoon Ragasa continued to move closer.

At noon, the super typhoon was estimated to be about 420 kilometers east-southeast of Hong Kong and was forecast to move west-northwest at about 22 km per hour across the northern part of the South China Sea, gradually edging closer to the coast of Guangdong, the HKO said in a bulletin.

“The outer rainbands of Super Typhoon Ragasa have started to affect eastern Guangdong. Ragasa has an extensive circulation with fierce winds, posing a severe threat to the coast of Guangdong,” the bulletin reads.

The observatory made a “pre-No 8 special announcement” at 12:20 pm, two hours earlier before issuing the signal No 8 to replace the strong wind signal No 3, which has been in force since 9:40 pm on Monday.

"The government advises members of the public with long or difficult home journeys or having to return to outlying islands to begin their journeys now," the special annoucement said.

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The forecaster said Ragasa will maintain super typhoon intensity and be closest to the vicinity of the Pearl River Estuary on Wednesday morning.

Depending on the distance between Ragasa and Hong Kong and the change in local wind conditions, the observatory said it will assess the need of issuing higher warning signals in the latter part of Tuesday night to early Wednesday.

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Reiterating its warning that the weather will be persistently adverse on Wednesday, the HKO stressed that gale to storm force winds will prevail, and winds may reach hurricane force offshore and on high ground, with frequent heavy squally showers and thunderstorms.

Meanwhile, seas will be phenomenal with swells and there will be a rise in water level of about 2 meters over coastal areas of Hong Kong on Wednesday morning under the influence of significant storm surge, according to the weather forecaster, adding that the maximum water level can generally reach around 3.5 to 4 m above chart datum.

With the departure of Ragasa, winds were expected to weaken gradually but showers will still be heavy at first on Thursday. The weather will improve in the latter part of this week.

READ MORE: Hong Kong steps up preparations as Super Typhoon Ragasa nears

In preparation for the super typhoon, the Emergency Monitoring and Support Center under the Security Bureau of the Hong Kong Special Administrative Region government was activated on Monday morning.

Chief Executive John Lee Ka-chiu said on social media that he visited the center in the morning to receive briefings from various response plans. He also held a meeting with Chief Secretary for Administration Eric Chan Kwok-ki and Secretary for Security Chris Tang Ping-keung to discuss in detail the efforts of different departments.

Lee said that the chief secretary for administration will lead relevant bureau heads to inspect different districts this afternoon to ensure that all departments are well-prepared for the super typhoon.

Meanwhile, the Education Bureau announced on Monday that classes in all schools, including secondary schools, primary schools, special schools, kindergartens, kindergarten-cum-child care centers and evening schools, will be suspended on Tuesday and Wednesday.

The Hong Kong International Airport will remain open, and a large number of flights are expected to be affected, according to Hong Kong's Airport Authority.

With Xinhua's inputs