Rain-on-snow

Stage = 88cm, too deep to wade!

First visit to Takiya this month. The water was even higher than last time on 27th April, due to continued snowmelt and some heavy rain over the past few days. Rain-on-snow events bring high water levels when rain falls on a melting snowpack. Especially if the rainy weather comes after a period of warm snowmelt conditions, and if the rain occurs with a strong warm wind. Warm winds can be more effective in melting snow than sunny weather! Early morning on 10th May a weather system passed over Niigata which brought very warm and strong winds, and heavy rain. Miomote AMeDAS station recorded 46mm precipitation with hourly rates up to 23mm. This caused a large rain-on-snow peak stage of 1.31m, as you can see in the stage hydrograph below. On other days with fine weather snowmelt, you can see the daily fluctuation in stage caused by the daily pulse of snowmelt entering the river (click on the chart to enlarge).

Takiya stage hydrograph (27 April - 13 May 2011)

Looking upstream to the bridge and gauging point

May 13th and still a patch of snow in the shade of the cedars at near sea-level (40m)