Mt. Fitzherbert

If the skies are clear as forecast, volcano watchers who turn out for the reopening of the Johnston Ridge Observatory on Friday will get a spectacular view of a hulking slab of rock that's rapidly growing in Mount St. Helens' crater.

It's jutting up from one of seven lobes of fresh volcanic rock that have been pushing their way through the surface of the crater since October 2004.

The fin-shaped mass is about 300 feet tall and growing 4 feet to 5 feet a day, though it occasionally loses height from rockfalls off its tip, said Dan Dzurisin, a geologist at the U.S. Geological Survey.