Tropical Storm Shanshan is a distinctively slow system. Weather officials cite as a reason the lack of strong westerly winds along its path.
The Meteorological Agency says a high pressure system blocked the storm as it headed northwest toward Kyushu.
The agency also says westerly winds and winds surrounding a high pressure system in the Pacific Ocean usually drive typhoons near Japan.
But this time, there were no such winds near Shanshan.
The agency suspects these were factors behind the storm’s slow speed.
Shanshan spent all of Thursday crossing Kyushu, after making landfall in Kagoshima Prefecture. Its speed continues to be low, at around 10 kilometers per hour.
An expert on typhoon mechanisms says global warming may be a factor affecting the storm’s speed.
Ito Kosuke is an Associate Professor of Disaster Prevention Research Institute of Kyoto University. He says, ” As global warming progresses, the latitude at which westerlies blow is expected to move further north. As a result, there’s concern the speed of typhoons may slow down.”
Ito also says Shanshan is an example of what can happen when a typhoon near Japan slows down.