Tropical Cyclone Chapala slammed into Yemen's central coast early Tuesday, lashing the area with maximum sustained winds of around 140 kph (85 mph).
But the major concern is the extraordinary volume of rain the storm system is expected to dump on the country's dry, rugged terrain, bringing a severe threat of mudslides.
Yemen typically gets around 100 millimeters (4 inches) of rain per year. Chapala was forecast to unleash two to three times that amount in the space of just one day.
The deluge is likely to cause "massive debris flows and flash flooding," CNN meteorologist Tom Sater warned.
The storm made landfall not far from Al Mukalla, a port that al Qaeda in the Arabian Peninsula seized
earlier this year amid the chaotic conflict engulfing Yemen.
Images from the city and surrounding Hadramout province showed streets and vehicles submerged by torrents of muddy brown flood water.
"The damage is enormous and we fear human losses," Minister of Fisheries Fahd Kafain told Agence France-Presse.
'We have no one to help us'
The country isn't used to finding itself in the path of tropical cyclones.
Reliable records, which only go back about 30 years, show no landfalls by hurricane-strength tropical cyclones in Yemen. Chapala, which was the equivalent of a Category 1 hurricane early Tuesday, had at one point been the second strongest storm ever recorded in the Arabian Sea
Most of the storms that brew in the Indian Ocean end up in the Bay of Bengal, on the eastern side of the Indian subcontinent. Those that do make their way across the Arabian Sea are more likely to hit Oman, which lies to the north and east of Yemen.
Chapala already brushed past Socotra, a Yemeni island in the Arabian Sea where 60,000 to 65,000 people live.
Abdul-Jamil Mohammed, deputy director of the Environmental Protection Authority on the island, reported strong winds, heavy rain and big waves overnight into Monday.
Mohammed said the storm damaged some homes and uprooted trees in Hadibo, the capital of Socotra. Contact has been lost with the northeastern part of the island since Sunday night, and floods have covered the roads leading there, he said.
"Our problem is we have no one to help us here," he said Monday, explaining the island has one hospital and four ambulances.
AFP reported Tuesday that more than 200 people on Socotra had been injured, citing Salem Zaher, the mayor of Hadibo.
Major humanitarian crisis
Yemen is already dealing with one of the largest humanitarian crises in the world, according to the United Nations.
The country has been plunged into chaos this year by a conflict between Houthi rebels
and forces loyal to deposed President Abdu Rabu Mansour Hadi. A Saudi-led coalition in March began bombing the Houthis, who are aligned with Iran.
Terrorist groups like al Qaeda and ISIS have capitalized on the unrest to expand their reach and try to foment sectarian tensions.
The widespread fighting has killed thousands of people, many of them civilians, and left millions more desperately short of food, water and medical supplies, the United Nations says.