WIND REPORTS.—Wind reports are mandatory.
Winds should be reported as relative direction and
speed. Estimate wind speed, and then determine wind
direction, as shown in figure 4-8. Wind direction is
always reported as the angle between the point from
which the wind is blowing and a line normal to the
beach. In addition, report the flank toward which the
wind is blowing, and whether it is blowing from
onshore or offshore. For example, winds would be
reported as REL WIND 030° 15 KTS R FLANK
ONSHORE or REL WIND 060° 08 KTS L FLANK
OFFSHORE.
If true wind direction and speed measurements can
be obtained, they should also be reported. For example,
report TRUE WIND 320 AT 12 KT. The true wind
direction and speed are used as inputs to modified surf
index calculations by using the Tactical Environmental
Support System (TESS) or the Mobile Oceanography
Support System (MOSS).
Onshore winds are normally favorable to
operations. Off-shore winds greater than 10 knots will
tend to increase the surf zone, increase wave steepness,
and produce a greater number of plunging breakers.
SECONDARY SURF.—Secondary surf is also a
mandatory remark when applicable. When sea waves
and swell waves or two sets of swell waves approach the
beach from different directions, the breakers may occur
in a large range of heights and periods, and the currents
produced in the surf zone may be very erratic and
dangerous. Information on the most significant set of
breakers is reported in the main report. For example,
report the larger breakers or report the breakers with the
shorter period if both wave sets produce breakers of
equal height. Complete information on the secondary
set of breakers is reported following HOTEL with a
remark, such as SECONDARY SURF ALPHA . . .
BRAVO. . . and so on, including all parameters ALFA
through ECHO. Elements FOXTROT and GOLF are
not reported for secondary surf. The effects attributed
to the secondary surf cannot be separated from the
evaluation of surf zone and littoral current.
The
presence of deep-water waves and the resulting lines of
breakers approaching the beach from different
directions are the primary factor requiring secondary
surf to be reported.
Q16.
Q17.
Q18.
Q19.
Q20.
Q21.
REVIEW QUESTIONS
How are littoral currents produced?
What may cause littoral currents to increase in
velocity?
How can rip currents be identified in a surf
zone?
What information is contained in element GOLF
in a surf observation?
How should an onshore wind blowing at 045° at
12 knots, and blowing from left to right (as
viewed from the beach) be reported in element
HOTEL?
What are the effects of secondary wave trains
moving into a surf zone?
Figure 4-8.—Surf/wind angle diagram.
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