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.
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
produce confused, steep waves.
T 4 - 8 sec
Weakly circulating tropical system with winds
under 45 mph.
Very steep seas.
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.
Saffir Simpson Hurricane
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.
Shape is usually roughly circular.
Highest waves are typically found in the right rear
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
Extreme waves in most open-ocean areas north
of 35o are produced by these systems.
H 3-5m T 5-10 sec
Low pressure system formed outside of
Large waves tend to lie in region of storm with winds
H 5-8m T 9-13 sec
parallel to direction of storm movement.
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
to be elliptical or circular.
and west coast areas.
H 13-18m T 15-20sec
Produce moderate storm conditions along U.S. east
coast south of 30o latitude when pressure gradients
T 4 - 10 sec
Slowly moving high-pressure systems.
Produce low swell-like waves due to long fetches.
T 5 - 10 sec
Permanent systems located in subtropical
Can interact with synoptic-scale and large-scale
weather systems to produce moderately intense wave
Southern portions constitute the trade winds.
(Sheet 2 of 3)
Meteorology and Wave Climate