Fine weather melt vs rain-on-snow

The above hydrograph shows the diurnal snowmelt pattern continuing through to mid-May, even though the snowpack was less than average this year. Dry fine weather continued during the last week of April and you can see this very clearly in the hydrograph by the gradually increasing diurnal snowmelt peaks. Both the daily peaks and the daily minimums are increasing, as mean daily temperature steadily rises from 8.6C on 23 April to 18.2C on 30 April.

During the first week of May cooler temperatures and a decrease in the snow-covered area are likely to have caused the decrease in water levels. However, a rain storm from the evening of 9 May (rain-on-snow event) caused a sudden rise in water levels and a moderate flood event. You can see the pattern of the hydrograph is very different comparing the fine weather melt during the last week of April to this rain-on-snow event on 9-10 May. Rainfall intensity reached 9 mm/h with a storm total of 27 mm at Miomote Amedas station. Much more rain likely fell in the mountains.

Stage = 55cm, Ta = 13.9C