The water level actually reached during a storm, expressed relative to a datum such as MHHW or the land vertical datum. It is the number that determines what floods, because a large surge at low tide may produce a lower storm tide than a moderate surge at spring high water. Evacuation maps and design flood levels are framed in storm tide, while scientists separating causes talk about surge.
Storm tide peaked at 3.4 metres above datum at 0200, that's the highest on the gauge record.
Also heard as
- total water level
- storm water level
Related terms
Storm surge
A rise of water above the predicted tide caused by a storm's winds and low pressure.
Astronomical tide
The part of the water level caused only by the gravitational effects of the Moon and Sun.
MHHW
Mean Higher High Water: the average height of the higher of each day's two high waters over the datum epoch.
High tide flooding
Shallow coastal flooding that happens when ordinary high tides exceed a local flood threshold, often without a storm.