防災科研　NIED

Snow and Ice Research Center

The “YukioroSignal”, a roof-snow condition alert

“YukioroSignal” = “Yukioroshi” + “Signal”
where “Yukioroshi” means roof snow removal in Japanese.

Roof snow should be removed before it become dangerous

Collapse of roof snow (January 31, 2018)
  • Before collapse at 09:08

    snow on the roof


  • After collapse at 9:58

    The snow slid off the roof and the passage was filled with snow.


An awful shop entrance (December 15, 2014)

  • It is very dangerous if snow cornices fall on pedestrians.


    入力してください

Recent study
Snow water equivalent distribution “YukioroSignal” for snow load alert

 Accident during roof snow removal is the most common cause of death by snow disasters in Japan 

If the snow is removed, there is a risk of falling from the roof, and if the snow is not removed, there is a danger of the house collapsing.
See Hirashima et al. (2020) in detail of the “YukioroSignal”.

How to make SWE distribution

  • INPUT : Snow depth data compiled from various Web site, and meteorological data from Japan Meteorological Agency (JMA).


  • Snow water equivalent is calculated using numerical snowpack model, SNOWPACK. For each points where snow depth is observed


  • For example, there are 140 snow depth sensor in Niigata prefecture (12,584km^2).


  • Interpolate data and make distribution.


“YukioroSignal” (SWE distribution) on the Web

The “YukioroSignal” is open access via Web sites of the NIED and several local governments during winter. 

  • SWE distribution for several prefectures is shown on the map.


  • Just expand and click, then the local snow load estimation is shown.


  • Just expand and click, then the local snow load estimation is shown.