The sign of Jonah is one of those things which looks like a Biblical inconsistency and the various ways that Christian scholars have tried to resolve it are hopelessly contrived. On the face of it, it looks like Jesus lied.
The Sign of Jonah
March 16th
Jonah gives us direct observation of the pillars of the earth. Direct observation is also known as empirical. The pillars of the earth aren't allegorical, metaphorical or theoretical, they're empirical.