CDMP Storm Hazard Atlas: Antigua

1
Antigua Probable Storm Effects
The projection of the illustrations is Plate
Carrée, a square grid of latitude and longitude.
Resolution is 30 arc-seconds. North-South
distances are true to scale. East-West distances
are stretched 4.5 at 16.825 degrees North, and
stretched 4.7 at 17.325 degrees North. All
model results were calculated using great-circle
distances based on the WGS84 datum.
Points of Interest
1. St. Johns Main town, with the harbour at the
end of a deep inlet.
St. Johns
2. Parham Harbour at the end of a broad, shallow
inlet.
1
2
Parham
3. English Harbour Shown as a three-sided cove.
Antigua
Note Waves and surges for Points of Interest
are reported from the nearest cell offshore.
3
N
English Harbour

• This set of maps is part of Section 2 of the
  Atlas of Probable Storm Effects in the Caribbean
  Sea, which was sponsored by the Caribbean
  Disaster Mitigation Project (CDMP), a joint
  effort of the Organization of American States
  (OAS) and the US Agency for International
  Development (USAID). These maps are a result of
  new techniques for modeling storms and
  estimating the probabilities of storms, developed
  in part under the patronage of CDMP. Refer to
  the Atlas for explanatory materials.
• WINDS represent sustained 1-minute winds at 10 m
  above the surface, and include both surface
  friction and topographic effects at a resolution
  of 30 arc-seconds. Friction factors derive from
  a Level I land-cover classification, with water,
  forest and open land predominating. If using
  wind damage models or building codes which
  internally include surface friction or
  topographic corrections, the nearest open-water
  wind speed from one of these maps may be used as
  input. Careful judgement is advised in reading
  and applying the values.
• SURGES include astronomical tide and setups from
  pressure, wind and wave, but not wave runup.
  Surges over land are shown as elevation above sea
  level, not water depth.
• WAVES are the heights of wave crests above the
  storm surge level in open water. Shoreline
  effects do not appear at this resolution.

2
Winds
10-Year Return Time
Antigua
1. St. Johns 32 m/s
1
2. Parham 32 m/s
2
3. English Harbour 33 m/s
3
N
3
Waves
10-Year Return Time
Antigua
1. St. Johns 1.3 m
1
2. Parham 1.7 m
2
3. English Harbour 4.1 m
3
N
4
Surges
10-Year Return Time
Antigua
1. St. Johns 0.5 m
1
2. Parham 1.1 m
2
3. English Harbour 0.3 m
3
N
5
Winds
25-Year Return Time
Antigua
1. St. Johns 40 m/s
1
2. Parham 40 m/s
2
3. English Harbour 43 m/s
3
N
6
Waves
25-Year Return Time
Antigua
1. St. Johns 1.7 m
1
2. Parham 2.2 m
2
3. English Harbour 5.4 m
3
N
7
Surges
25-Year Return Time
Antigua
1. St. Johns 1.0 m
1
2. Parham 1.7 m
2
3. English Harbour 0.5 m
3
N
8
Winds
50-Year Return Time
Antigua
1. St. Johns 47 m/s
1
2. Parham 47 m/s
2
3. English Harbour 49 ms
3
N
9
Waves
50-Year Return Time
Antigua
1. St. Johns 2.0 m
1
2. Parham 2.6 m
2
3. English Harbour 6.1 m
3
N
10
Surges
50-Year Return Time
Antigua
1. St. Johns 1.3 m
1
2. Parham 2.1 m
2
3. English Harbour 0.7 m
3
N
11
Winds
100-Year Return Time
Antigua
1. St. Johns 52 m/s
1
2. Parham 52 m/s
2
3. English Harbour 54 m/s
3
N
12
Waves
100-Year Return Time
Antigua
1. St. Johns 2.3 m
1
2. Parham 2.9 m
2
3. English Harbour 6.7 m
3
N
13
Surges
100-Year Return Time
Antigua
1. St. Johns 1.5 m
1
2. Parham 2.6 m
2
3. English Harbour 0.9 m
3
N