For the second time this year, forces of nature and gravity have blocked one of the primary access routes to Yosemite National Park, with El Portal Road (Highway 140) closed at least through this weekend after a rockslide covered 150 feet of the road under up to 20 feet of debris.

The weather is getting warmer, even hotter in some national parks, and while rivers are alluring for their ability to cool you off, they also can quickly kill you. In Yosemite National Park, rangers have been working on their swift water rescue techniques to save your life, but the best measure of safety is to stay out of the water, as this video explains.

National park staff in some parts of the country are warning visitors to expect crowds this Memorial Day holiday weekend, with some superintendents suggesting you head someplace else on Saturday.

If all goes as planned, the Glacier Point Road at Yosemite National Park was to open to traffic Thursday at 9 a.m.