weather and water wisdom 259
Low Pressure Center Bears West (Northern Hemisphere)
Wind signals
Th e wind will be steady; no wind shift will occur until the center passes.
If the winds are southerly, the system is approaching.
If the wind shift s 180 degrees, the center is passing over you.
If the winds are northerly, the center has passed by.Barometer signals
Th e barometer will be lower than normal and dropping rapidly.
When the barometer bottoms, the center lies over you.
When the barometer rises rapidly, the center has passed by.Action to take (Northern Hemisphere): Make best speed and head north to
take yourself out of the storm path. Keep heading north until the winds shift
to the northwest and the barometer begins to rise.
Meeting a Line Squall
You’ve watched those jagged-edged clouds building to the west for the past
hour. A fl attish roll cloud signals that this line squall is moments away. Don’t be
fooled when no rain comes from these clouds. First, you’ll feel the temperature
drop. Th en, the winds will veer 60 to 90 degrees to the right, accompanied by
torrential rain, lightning, and thunder. One of Mother Nature’s most spectacular
sound and light shows has begun.
WHAT TO EXPECT AND HOW TO PREPARE
Make preparations when you fi rst sight a squall line to the west of your position.
Below is a list of weather elements you should prepare for, followed by specifi c
steps to take, depending on whether you are in coastal or inland waters. You
can expect the following:
wind direction shift s clockwise 60 to 90 degrees
wind speed is 35+ knots
visibility is less than 100 yards
lightning and thunder is intermittent
the squall will last less than 45 minutesFollow one of the two preparation and action steps below. If in inland, re-
stricted waters use the first method. Vessels in open waters or offshore should
use the second method.