Warming temperatures are leading to renewed concerns of flooding in the Yosemite Valley this week, with weather and state water officials keeping a watchful eye on the Sierra’s massive snowpack.

The National Weather Service on Sunday upgraded its flood watch for the Merced River at Pohono Bridge in Yosemite Valley to a flood warning.

The NWS said on Twitter the Merced River through Yosemite “will stair-step upward through the week as snow melts during this week’s heat wave.”

Much of the valley from Highway 120 is closed, due to the likely flooding. Park officials say some areas may not reopen until June.

Park officials said Lower and North Pines campgrounds and the Housekeeping Camp closed beginning Monday.

Yosemite Valley, the Mariposa Grove, and Wawona remain accessible from highways 140 and 41.

The California Department of Water Resources said on May 1 the Sierra snowpack was at 241 percent of normal.