Halliday & Matthiessen (2014: 373):
Also found in the post–Deictic position in the nominal group are words expressing the speaker’s attitude (to the thing, or else to the world in general), such as wretched, miserable, lovely, splendid, as in those lovely two evenings in Bali. …The attitude may be focused on the number represented by the Numerative (with a singular determiner a(n) as Deictic and a plural noun as Thing):For a lousy two weeks in New Jersey, you’ll make a shitload of dough.