Feb. 13 (UPI) -- Due to a lack of water, Yosemite's Horsetail Fall may not flow this year meaning the glowing "firefall" phenomenon may not be visible.
The waterfall falls over the edge of El Capitan, a vertical rock formation in Yosemite National Park in California. The water usually only falls during the winter and during sunset in February, the backlighting from the sun can create a "firefall" effect in which the thin trail of water appears gold or orange.
The phenomenon draws thousands of tourists each year, requiring Yosemite to put in place measures to prevent damage to surrounding vegetation as hikers get in place for a view.
This year, the park warned there may be nothing to see at all, as Horsetail Fall has "little to no water."
Sight of the "firefall" can be hit or miss each February, as "even some haze or minor cloudiness can greatly diminish or eliminate the effect," the park says on its website.