Are you willing to produce really ugly writing? Sometimes, there's just no other way. There are going to be times when putting something (anything) on the page is the most important task. The details can always come later.
The Beauty of Ugly Writing
There are moments in every writer's journey where suddenly, it's all easy. The words just somehow flow magically, appearing on the page through your fingers with absolutely no effort whatsoever. Later when you go back to read it, you're amazed.
Then, there are those other moments when it physically hurts to get words on the page. When everything you write just looks terrible, and every word is difficult. But there's beauty to be found even in ugly writing. You can always come back and do your editing later, clean up that text and add all the necessary details.
Just get down the rough bones of the story, write the stuff that's supposed to happen (no matter how ugly), and add all the descriptors later. Writers are supposed to write...right?