EM 1110-2-1100 (Part II)
(Change 1) 31 July 2003
Table II-2-2 (Continued)
Mesoscale Convective Complex (MCC)
Important in interior regions of U.S.
H fetch-limited
T fetch-limited
Large, almost circular system of
Can generate extreme waves for short-fetch and
U . 20 m/s
thunderstorms with rotation around a central
intermediate-fetch inland areas.
point (2-3 form in the U.S. per year).
Size, 100-400 km in diameter
Squall lines superposed on background winds can
H 1-4m
Tropical depression
produce confused, steep waves.
T 4 - 8 sec
Weakly circulating tropical system with winds
under 45 mph.
Very steep seas.
H 5-8m
Tropical storm
T 5 - 9 sec
Circulating tropical system with winds over
Highest waves in squall lines.
45 mph and less than 75 mph.
Can produce large wave heights.
Hurricane
Saffir Simpson Hurricane
Scale
Intense circulating storm of tropical origin
Directions near storm center are very short-crested and
SS H(m) T(sec)
with wind speeds over 75 mph.
confused.
1
4-8
7-11
2
6-10
9-12
Shape is usually roughly circular.
Highest waves are typically found in the right rear
3
8-12 11-13
quadrant of a storm.
4 10-14 12-15
5 12-17 13-17
Wave conditions are primarily affected by storm
intensity, size, and forward speed, and in weaker
(see Table IV-1-4)
storms by interactions with other synoptic scale and
large-scale features.
Extratropical cyclones
Extreme waves in most open-ocean areas north
Weak:
of 35o are produced by these systems.
H 3-5m T 5-10 sec
Low pressure system formed outside of
Moderate:
tropics.
Large waves tend to lie in region of storm with winds
H 5-8m T 9-13 sec
parallel to direction of storm movement.
Intense:
Shapes are variable for weak and moderate
H 8-12m T 12-17sec
strength storms, with intense storms tending
Predominant source of swell for most U.S. east coast
Extreme:
to be elliptical or circular.
and west coast areas.
H 13-18m T 15-20sec
Produce moderate storm conditions along U.S. east
H 1-4m
Migratory highs
T 4 - 10 sec
Slowly moving high-pressure systems.
become steep.
Stationary highs
Produce low swell-like waves due to long fetches.
H 1-3m
T 5 - 10 sec
Permanent systems located in subtropical
Can interact with synoptic-scale and large-scale
ocean areas.
weather systems to produce moderately intense wave
generation.
Southern portions constitute the trade winds.
Very persistent wave regime.
(Sheet 2 of 3)
II-2-26
Meteorology and Wave Climate
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