Water level and barometric pressure graphs on January 15, 2022

Water level and barometric pressure graphs from a NOAA tide gauge station in Port San Luis, California, on 15 January 2022. They show a meteotsunami wave about 20 centimeters (8 inches) high at 04:00 a.m. PST (11:00 a.m. GMT), shortly after a spike in barometric pressure that marked the arrival of the first atmospheric wave. About 3 hours later, the classic (“predicted”) tsunami waves arrived. For reference, the first big explosion in Tonga occurred at about 04:15 a.m. GMT, nearly 7 hours before the first atmospheric wave reached Port San Luis. Graphic courtesy of NOAA NOS Senior Scientist Greg Dusek.