CoastWatch | Coastal Flooding & High-Tide Risk

How to read this map

Hazard / signal: NOAA high-tide-flood likelihood and NWS coastal alerts
Exposure: coastal county population
Consequence / vulnerability: CDC/ATSDR SVI

Official/source values remain distinct from MitchellCo derived screening scores.

Where are elevated coastal-water levels most likely to affect populated, vulnerable communities?

NOAA renders independently from NWS and CDC. Before CDC is called, CoastWatch checks a 15-day per-state population cache. County geometry/SVI still comes from the CDC endpoint because state population alone cannot support county-level scoring.

Data health

NOAA high-tide likelihoodLoading

NWS coastal alertsLoading

CDC county / SVILoading

Model/data age: waiting…

LayersNOAA high-tide stationsNWS coastal flood / surge alertsCDC vulnerability context

Legend

LowDerived concern < 35Elevated35–59High60–79Very high80+

Highest coastal concern

#	Station	NOAA likelihood	Score
Waiting for data…

How the score works

Derived Coastal Concern, 0–100
NOAA HTF likelihood: 0.60 × likelihood %, max 60
NWS coastal alert at station point: Warning 20, Advisory 12, Watch 8
County vulnerability: 12 × SVI percentile rank
County population exposure: min(8, 1.3 × log10(population + 1))
cap at 100.

Loading & reliability

NOAA loads at startup/manual refresh; NWS refreshes every 5 minutes; CDC SVI is 2022 vintage and loads on coast changes. Large raw responses are not stored in localStorage. Only normalized state population totals use versioned 15-day entries. Cache read/write failure is non-fatal. Transient endpoint failures use bounded exponential backoff. Failure of NOAA, NWS, CDC, or local storage never blocks the other sources or UI.

Sources, cadence & attribution

NOAA CO-OPS Derived Product API: High Tide Flooding Daily Likelihoods.

National Weather Service Alerts API: coastal flood/surge products; geometry-null products resolve affected zones when needed.

CDC/ATSDR Social Vulnerability Index 2022: county population and SVI rank.

Basemap © OpenStreetMap contributors.