behold. Figure of speech Asterismos (App-6), to call attention to another stage of "the great conflict". See App-23. This is not the same tempest as that recorded in Mar_4:37-41, and Luk_8:23-25. This was before the calling of the Twelve: the other was after that event. There is no "discrepancy", if we note the differences on p. 1325, and App-97.
tempest = earthquake. Always so rendered in the other thirteen occurrences. In the later event it was a squall (Greek. lailaps).
was covered = was getting covered. Hence it was a decked boat. In the later miracle it was an open boat, "filled".