Storm surge vs flooding: what is the difference

Storm surge in plain terms

Storm surge is ocean water pushed onshore by wind and pressure. It is a fast-moving wall of water and can rise quickly before landfall.

Surge is strongly tied to storm size, forward speed, angle of approach, and coastal shape.

Rain flooding is a different threat

Rain flooding builds over hours as drainage systems overflow. It can impact inland neighborhoods far from the coast.

Urban streets and low-lying areas often flood even without a named storm.

How surge forecasts are issued

The National Hurricane Center issues storm surge watches and warnings based on SLOSH models and forecast tracks.

Surge forecasts update with each advisory and can shift quickly as track and intensity change.

Why surge maps stop inland

Surge models track coastal inundation and tidal waterways. Inland locations often have no surge data, which is why surge tiles are marked unavailable away from the coast.

Evacuation timing signals

Surge is the main driver of evacuation zones in coastal counties. Local emergency managers issue zone-specific orders based on surge height and timing.

If you are in a surge zone, timing matters more than wind category. Roads can flood before the storm core arrives.

How to plan for both hazards

Coastal homes need evacuation timing and surge prep. Inland homes need rainfall mitigation and drainage checks.

• Track surge forecasts and evacuation zones near the coast.
• Clear drains, gutters, and low spots before heavy rain.
• Use both surge and flood scores to prioritize upgrades.
• Keep a plan for vehicles and valuables in flood-prone areas.