Thousands of kilometres apart, the mountains of central Italy and the snowy landscapes of Japan’s Niigata Prefecture may seem to have little in common. Different cultures, different geographies, different climates. Yet, under certain winter conditions, remarkably similar meteorological processes unfold on both sides of the world.
One of these is the phenomenon known as lake-effect snowfall. It occurs when cold air masses move across relatively warm bodies of water, absorbing heat and moisture before releasing them as intense snowfall once they reach land and are forced to rise by mountain ranges.
In Italy, this process can affect the Adriatic coast and the central Apennines. In Japan, it shapes some of the country’s most famous snowfalls along the coast of the Sea of Japan. These events are not only part of the identity of mountain regions: they are also a vital water resource and, at times, a significant natural hazard.
During his visit to CIMA Research Foundation, meteorologist Katsuya Yamashita from the Snow and Ice Research Center of the National Research Institute for Earth Science and Disaster Resilience (NIED) has been exploring these surprising similarities between Italy and Japan. His work investigates how lake-effect snowfall develops in mountainous regions, how climate change may reshape these processes, and what researchers and communities can learn from comparing experiences across continents.
We spoke with him about snow, science, collaboration, and what it means to study a phenomenon that is both beautiful and increasingly complex in a warming world.
Following snow across continents
Katsuya Yamashita studies snow, but his scientific journey did not begin there.
“My scientific background began with aerosol science during my university years,” he explains. “I became interested in how aerosols and clouds influence climate change, which led me to study aerosol science at university.”
After graduating, he joined the Meteorological Research Institute, where he worked on cloud microphysics and artificial precipitation and snowfall. Today, at the Snow and Ice Research Center of the National Research Institute for Earth Science and Disaster Resilience (NIED), his work focuses primarily on cloud particles, snowfall processes and their evolution in a changing climate.
His visit to CIMA Research Foundation is part of an overseas fellowship programme promoted by NIED, but it is also an opportunity to strengthen an existing collaboration between the two institutions.
“CIMA has an Memorandum of Cooperation with NIED and conducts research on snow, meteorology, climate change, and disaster risk reduction – areas closely aligned with my own work at NIED. I decided to spend my fellowship at CIMA in the hope of learning about research practices and approaches to international collaboration in Italy and Europe. The goal is to understand how snow conditions are changing in both countries and what can be learned from comparing regions that, despite their distance, share surprisingly similar meteorological characteristics.”
The common language of lake-effect snowfall
“The idea of making a comparison first came to me when Francesco Avanzi (ed.n. snow hydrology researcher at CIMA Research Foundation) told me that Italy also experiences snowfall caused by the lake effect.”
What caught Yamashita’s attention was the similarity between the two regions.
“The geographical configuration of the Adriatic Sea, the coastal area, and the Apennine Mountains is similar to that of the Sea of Japan, the coastal region, and the Echigo Mountains in Niigata.”
That observation became the starting point for a comparative study of lake-effect snowfall in Italy and Japan. Despite the geographical distance, the mechanism is remarkably similar.
“The common feature in both regions is that snow clouds, which develop over the sea as they gain moisture and heat, reach land and intensify further as they are lifted by the forced ascent along mountain slopes. This is the general mechanism of lake-effect snowfall, and we were able to demonstrate it using data from Italy, without finding any surprising differences between the two contexts. However, I have been struck by the diversity of snowfall processes in the Apennine Mountains, which differs greatly from what we observe in Japan.”
This complexity can make snow-damage mitigation particularly challenging and highlights the importance of improving knowledge of local snowfall processes.
Snowfall in a warming climate
Climate change is already reshaping snowfall patterns, raising new questions about how lake-effect snowfall may evolve in both countries.
“Based on research conducted in Japan, the projected impacts of global warming on snowfall are as follows: a decrease in total snowfall, an increase in the frequency of heavy snowfall in high-altitude areas, a decrease in snowfall in low-altitude coastal regions as snow increasingly shifts to rainfall, and a shorter snowy season due to a delayed start and an earlier end.”
For researchers, one of the key challenges is understanding where these changes will be most pronounced.
“We believe it is important to scientifically identify the specific regions and altitude ranges where these impacts are most pronounced. Our current research aims to clarify these points based on scientific evidence.”
Living with snow
Japan’s long experience with heavy snowfall has not eliminated the challenges that snow creates for communities. In response, researchers are working to transform practical experience into operational knowledge.
“One project focuses on converting the expertise of ski resort managers and avalanche professionals into measurable indicators that can be compared with forecasts and observations, helping authorities act earlier and more effectively”.
At the same time, Japan has increasingly adopted preventative road closures and planned transport suspensions before major snowfall events occur. According to Yamashita, these measures are intended first and foremost to protect lives, but they can also reduce the time and costs associated with managing large-scale disruptions.
Seeing mountains through a scientist’s eyes
Years spent studying snow have inevitably changed the way Yamashita looks at mountain landscapes.
“Because I have seen many snow-covered mountains, I often find myself viewing them from a scientist’s perspective. The first things I look at are the steepness of the slope and how much snow appears to have accumulated.”
His attention immediately turns to safety, assessing whether conditions allow people to move through the landscape without risk. Yet, beyond the scientific analysis, snow remains for him something more than a meteorological phenomenon. It is a force that shapes landscapes, resources, risks and communities, and one that continues to inspire both scientific curiosity and personal fascination.
“From a more general standpoint, the scenery of Japan’s snow-covered mountains is incredibly beautiful, as exemplified by Mount Fuji in winter. I truly hope you will consider visiting them.”