On the morning of 4 January 1789, M. Michaud corresponding member of the Academy of Science of Turin at Nice observed "an immense group of clouds like towers piling up". This not only drew his attention but also allowed him to make a prediction to his two older sons:
“[...] nous aurions bein pu decouvrir quelque trombe de mer dans la journee
(we could discover some waterspouts during the day)”
Approximately two hours later at 10:05 am, Michaud observed at sea the "embrion of a waterspout" surrounded by "high plumes like sails pushed by the wind toward the surface" (a in Fig. 1). The structure narrowed and was later observed as a "column of fog" over land (b in Fig. 1).
Fig. 1 - The "embrion of a waterspout" at Nice on 6 January 1789.
At 11:52 am the confirmation of Michaud's prediction arrived, as his second son, now in charge with the observations, shouted: "Mon Pere, une trombe de mer superbe!" (Michaud 1801, p. 6). Fig. 2 shows the "superb" waterspout "passing majestically in front of Nice". The base of the waterspout, which was as the beginning "calm" was now "a veritable volcano crater" with parabolic jets of water emerging from the centre. As Michaud and his sons were watching this "extraordinary spectacle" hail (1-1.5 cm in diameter) begin to fall.
Fig. 2 - The first waterspout observed at Nice on 6 January 1789.
Soon after, a second waterspout begin to form and was observed initially only at the surface of the sea (a in Fig. 3). The vertical structure of the waterspout became apparent (c in Fig. 3) once the pendant structure from the cloud indicated as (b) in Fig. 3 moved over the sea surface structure.
Fig. 3 - The evolution of the second waterspout observed at Nice on 6 January 1879.
The account of the waterspouts from 4 January together with some speculations regarding their formation were published by Michaud in Memoires de l'Academie de Turin in 1801. This account contains, to my knowledge, the first verified waterspout forecast for Europe. The article, which also contains a description of two waterspouts observed in 19 March 1789 Nice (Fig. 4) was translated to German an published in Annalen der Physik in 1801.
Fig. 4 - Waterspouts observed at Nice on 19 March 1789.
Reference:
Michaud, 1801: Observations sur les trombes de mer vues de Nice en 1789, le 6 Janvier et le 19 Mars. Memoires de l' Acad. de Turin, Tome 6, p. 3–22. (via gallica.bnf.fr).