DisasterWatch | FEMA Declarations & Community Impact

How to read this map

Hazard / event: recent FEMA federal disaster declarations and incident type.
Exposure: CDC/ATSDR population represented by counties with valid 2022 SVI values, aggregated to state level.
Consequence / vulnerability: FEMA assistance programs, declared-area breadth, and mean county SVI percentile.

FEMA and CDC values are official source data. The MitchellCo attention score and marker placement are non-official screening aids.

Where are recent federal disaster declarations broadest, and where do they overlap larger or more vulnerable populations?

FEMA renders first. CDC state context is checked locally before the CDC endpoint is called. Valid state context is cached for 15 days; storage or CDC failure never blocks FEMA, rendering, or other UI work. Markers use representative state coordinates, not incident locations.

Data health

FEMA declarationsLoading

CDC population / SVIQueued

Loading primary signal…

Legend

Major Disaster (DR)Emergency (EM)Fire Management (FM)Other FEMA type

Radius reflects distinct designated areas. After CDC context loads, halo opacity reflects derived attention.

Highest derived attention

#	State	Recent activity	Score
Waiting for FEMA and CDC context…

Derived attention score

declaration = max(DR 30, EM 22, FM 14, FS 10)
recency multiplier = 0.65 + 0.35 × max(0, 1 − newestAgeDays/windowDays)
hazard = declaration × recency multiplier, max 30
scope = min(25, 8 × log2(distinctDeclaredAreas + 1))
assistance = min(15, 6 if IA/IH + 5 if PA + 4 if HM)
exposure = min(15, 2.15 × log10(representedPopulation + 1))
vulnerability = 15 × meanCountySVIPercentile
attention = hazard + scope + assistance + exposure + vulnerability, capped 100

Population is state context, not an estimate of people affected. Mean county SVI is not population-weighted. The score does not estimate damages, casualties, eligibility, or unmet need.

Score edge cases checked

Zero declarations produces no score. One recent DR area has only 8/25 scope points. Two areas produce about 12.7/25. A record as old as the selected window receives 65% of its declaration-type points. A recent DR with broad scope, all assistance categories, large represented population, and high mean SVI reaches the 100 cap without any component exceeding its published maximum.

Refresh & performance

OpenFEMA refreshes every 20 minutes. The first FEMA page renders immediately; additional pages use concurrency three and failed later pages do not erase the successful first page. CDC/ATSDR SVI is 2022 vintage. State aggregates use versioned per-state localStorage entries with a 15-day TTL. A valid cache skips the CDC endpoint. Cache reads/writes are non-fatal. Transient CDC failures use bounded exponential backoff. Automatic refresh pauses while hidden or offline and never resets pan, zoom, or popups.

Sources & attribution

OpenFEMA Disaster Declarations Summaries v2: official declarations. API: https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries.

CDC/ATSDR Social Vulnerability Index 2022 county layer: E_TOTPOP and RPL_THEMES, aggregated server-side by state.

Basemap: USGS The National Map USGSTopo tiles.