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

Before collapse at 09:08


After collapse at 9:58

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

See Hirashima et al. (2020) in detail of the “YukioroSignal”.

• Hirashima, H., T. Iyobe, K. Kawashima, and H. Sano, 2020: Development of a snow load alert system, "YukioroSignal" for aiding roof snow removal decisions in snowy areas in Japan. J. Disaster Res., 15(6), 688-697.

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 (12,584km2).

“YukioroSignal” (SWE distribution) on the Web

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

URL　https://seppyo.bosai.go.jp/snow-weight-niigata/

SWE distribution for several prefectures is shown on the map.


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


The color coding conforms to the ISO 22324:2015 Societal security - Emergency management - Guidelines for color coded alert.