Here 𝓟 reads tempests, in the plural, while the 1830 edition reads tempest, in the singular. The conjoined nouns in this sentence are in the plural (“and the whirlwinds and the thunderings and the lightnings”) except for the final one (“and the exceeding great quaking of the whole earth”). In addition, there is nearby evidence for the replacement of tempests with tempest in the early text, although in this case the singular form occurs in 𝓟, if only momentarily, rather than in the 1830 edition:
In this instance, Oliver Cowdery initially wrote tempest in 𝓟 but virtually immediately corrected it to tempests (there is no change in the level of ink flow for the inserted s). Also note that in this passage we once more have the plural tempests conjoined with the plurals thunderings and lightnings, which is then followed by the singular quaking. Further support for the conjoining of plural tempests and whirlwinds occurs a little later in 3 Nephi:
Thus it seems quite reasonable to assume that the singular tempest in the 1830 edition for 3 Nephi 8:12 is an error for tempests.
In 3 Nephi 8:19, a little further on in this chapter, we get the singular tempest, but it is conjoined with an immediately preceding singular noun, storm; interestingly, in this passage we get the plural quakings rather than the singular quaking:
Yet here the semantics and syntax are somewhat different than the two cases in 3 Nephi 8:12, 17. For further discussion of variation in the grammatical number for tempest(s), see under 1 Nephi 19:11. Also see the case under 3 Nephi 22:11, a biblical quotation from Isaiah 54:11, which gives an example where scribe 2 of 𝓟 miswrote tempest as tempests.
Summary: Restore the plural tempests in 3 Nephi 8:12 (the reading of the printer’s manuscript); apparently the 1830 compositor accidentally dropped the plural s when he set the type from 𝓞.