Do you specifically need strobe? Keep in mind that you can manually "strobe" a light with a forward clicky switch. It might not be as consistent as a normal strobe, but might be adequate enough.
The Jetbeam Jet III M apparently has a strobe and a programmable output mode, but isn't fully regulated on an 18650. You might want to look at the fenix TK11 or Eagletac T10L (or T10LC2), which both have medium and high modes, as well as forward clickies.
None of these will be truly "waterproof," but they should stand up to rain and some dunking.