In their passage disturbances act on the tide with a sort of impulsive stimulation , the "storm surge", following which the Adriatic, because of the shape of the basin, it behaves as a resonant cavity:  at the end of the pulse remains a troubled situation in sea level, which is manifested by a series of longitudinal and transverse oscillations, the "seiches", whose amplitude fades over time. The fundamental oscillation, longitudinal, has a period of 22 hours.
The latter component must be taken into account in predicting tide: it happens often enough that in the days following a "storm surge ", due to the phase shift of almost two hours between the frequency of the astronomical tide (about 24 hours) and the seiche (about 22 hours), the oscillation could be in phase with the highest astronomical tide and lead to high water.
A clear example can be seen in the graph below which refers to the period 12 to 15 February 1972: the maximum meteorological contribution occurred on the day 12, while the observed sea level has reached the maximum value after two days, February 14, despite improved weather conditions, when astronomical and meteorological contribution are found more in phase.