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FEMA flood zones · Alaska

North Slope Borough, Alaska Flood Zone Map

1 flood insurance claims·$55,782 paid·2 federal flood & hurricane disasters

FEMA’s digital flood map shows no high- or moderate-risk zones in North Slope Borough. That can mean the area was never studied in detail or has no digital map, not that it can’t flood; the county floodplain administrator can say which.

Share of the whole county outline, rivers and lakes included; parts FEMA hasn’t mapped count as zero.

Coastal high risk (V, VE)FloodwayHigh risk (A, AE)Moderate (X, 500-year)Minimal (X)Undetermined (D)

Shaded areas are FEMA’s mapped flood hazard zones in and around North Slope Borough, Alaska. Zoomed out they are simplified; at street level the map switches to FEMA’s exact layer. Tap anywhere to check that spot, or search an address above.

How deep the water got

outlet80″ door12″24″36″48″60″72″84″

In flood insurance claims here that reported a flood depth, the average was 1 inches.

Drawn to scale against an 80-inch door. Even a few inches soaks flooring, the bottom of the drywall and anything plugged in near the floor.

Average of the depths reported on claims (zero and implausible values left out); FEMA’s record doesn’t say exactly where each depth was measured. Source: OpenFEMA NFIP claims.

In their words

1 NOAA storm reports from North Slope Borough describe what happened, in the words of the forecasters who covered it. Read the Alaska flood stories →

Federal disasters

8 federal disaster declarations since 1986, 2 of them floods, coastal storms or hurricanes.

DisasterBegan
Severe StormSep 28, 2017
Severe StormAug 27, 2015
Severe Winter Storms And FloodingNov 8, 2011
Severe Storms, Flooding, Landslides, And MudslidesJul 27, 2008
Severe Winter StormJan 7, 2005
Coastal Storm, High Winds & WavesSep 20, 1986

Weather and water disasters only; most recent first. Source: OpenFEMA Disaster Declarations.

Recorded flood events

1 since 1996: 1 river or area floods.

EventDateDamage
FloodDec 20, 2022—

— = no damage estimate in the record. Source: NOAA Storm Events Database.

From the storm reports

Flood · Dec 20, 2022. Heavy rainfall observed on December 20,2022 prompted a flood warning for Unalaska, a city along the Aleutian Chain, where 3-4 inches of rainfall led their Public Safety to issue a precautionary Cat 2 travel advisory (only drive when necessary; Cat 3 closes travel). About a 1 mile stretch of Ballyhoo Road was closed due to flooding and debris on the roadway. Manholes were displaced to allow for better drainage.

National Weather Service narratives, lightly trimmed. Source: NOAA Storm Events Database.

The zones you’ll see on the map

Every colour on the map above is a place on this drawing: where the ground sits relative to the flood FEMA plans for.

Cross-section of a river floodplainDiagram: a river valley. The floodway is the channel and the land beside it; the 1%-annual-chance flood surface (the base flood elevation) covers the valley floor as zone A or AE; a narrow band higher up is shaded X, the 0.2% floodplain; higher ground is X.0.2% CHANCE A YEAR (500-YEAR)BASE FLOOD ELEVATION · 1% A YEARXAEFloodwayAEX
  1. A / AE Inside the 1%-a-year floodplain: about a 26% chance of flooding over a 30-year mortgage. AE has a mapped base flood elevation; plain A does not.
  2. Floodway The channel and the land beside it that has to be kept clear enough to carry the flood. Building here is tightly limited.
  3. X shaded The 0.2% (500-year) floodplain, plus some levee-protected and very shallow flood areas.
  4. X Outside both lines. No federal requirement to insure, which is not the same as no risk.

Every flood zone code explained →

Flood insurance in North Slope Borough

If a building in North Slope Borough is in a high-risk zone (A or V) and its mortgage comes from a federally regulated or insured lender, or is federally backed, flood insurance is required.

Outside those zones it is optional, and often worth having: from 2014 to 2024 nearly one-third of NFIP claims came from outside the high-risk Special Flood Hazard Area. Since Risk Rating 2.0, NFIP premiums are set for each building, so the only reliable price is a quote: FloodSmart.gov or a local agent.