JP 3-50 National Search and Rescue Manual Vol I - US Navy

eturn to base.
E. Continuous attention must be given to weather conditions. When
each SRU is on its first search leg, it should transmit on scene weather
to the OSC, who transmits consolidated information to the SMC. The most
important weather factors are winds, water currents, visibility, and
cloud coverage; surface SRUs may also report air and water temperatures.
These observations should be as accurate as possible; relatively minor
differences in direction and speed between forecast winds and actual
winds may result in the search object being outside the planned search
area.
1. Wind direction may be estimated by observing wind effects on
land and water surfaces. On water surfaces, wavelets and
whitecaps appear to move into the wind, wave systems move down
wind, and windstreaks and foamstreaks align with the wind. On
land, flags, clothes hanging on wash lines, tree limbs, dust,
and snow align with the wind. Wind direction can also be
determined if smoke is present. Care should be taken not to
use smoke signals or smoke grenades in areas covered with fuel
or combustible vegetation.
2. Water currents can sometimes be estimated by observing water
color, kelp streaks, and mud and silt streaks, or by measuring
water salinity and temperature. Major currents are normally
well defined and their boundaries easily detected by color or
temperature changes.
3. The SMC plans searches on the basis of existing and forecast
weather. If ceiling and visibility deteriorate below that
forecast, the assigned track spacing could result in lower
coverage factor and POD even though the full search area will
be searched. Therefore, the SMC should provide the OSC with
guidance, if weather deteriorates, on whether to maintain
specified track spacing, or to compress track spacing to
attain the desired POD but in a smaller area.
6-3