The Sierra Nevada snowpack experienced accelerated melting early this week as very warm temperatures gripped the region, raising the risk of several dangers.

Snowpack in the Sierra from this past winter was still well above average to begin May. The SNOTEL network estimated water content of the snowpack in the Sierra was still from three to six times the average for the week before Memorial Day.

With well-above-average temperatures in place early this week, melting of that snowpack was accelerated.

The Walker River in western Nevada had been forecast to top a record, which could have caused significant property damage near the towns of Mason and Yerington. As of Monday, the forecast crest for the river had been reduced based on new data, with minor to moderate flooding now expected.

Preparations for the potential flooding are being encouraged. Sandbagging efforts are underway and crews are working to build up levees in Yerington , according to posts on the Lyon County, Nevada, Facebook page.

The Humboldt River is expected to reach moderate flood stage, which could lead to sewer backups in low spots of Winnemucca, Nevada, and flood some rural roads.

The NWS is encouraging any visitors in the larger Sierra Nevada region to avoid camping in and around rivers or streams given the projected rises and higher flows. Peak flows from snowmelt typically occur in the evening and overnight, posing a danger to campers that set up near a waterway for the night.

Another danger to consider is that the water will be very cold. That could raise the risk of hypothermia for those that spend even a small amount of time in the water.

Another warm snap kicking in Memorial Day weekend will continue to replenish rivers with snowmelt into early June.

(MORE: Summer 2017 Temperature Outlook )

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