"Wyatt Emmerich" wrote
Let's say you take off on a long cross country with no forecast of icing. By
the time you arrive at your destination, a 2,000-foot layer exist below you
with temps of 30 F. You are getting low on fuel. Is it legal to descend
through the thin layer even if you are in an airplane without known icing?

No, it's not legal.

However, since you are low on fuel and above an icing layer, you are
in an emergency situation. You can thus ignore the prohibition on
operating in known icing conditions (assuming your airplane has one)
and descend anyway, since that's what's required to meet the
emergency.

Your condition is EXACTLY the same as that of a VFR pilot who relied
on a forecast of clear skies over his destination, went over the top,
had the forecast go bust, and is now trapped above a solid layer. The
only difference is that he's more likely to come out of this unscathed
than you.

Michael