Signs of impending Typhoon
Every typhoon is different and there are many
factors that contribute to its development.
However, the following is a general sequence of
events that could occur during the development
of a Category 2 typhoon (wind speed 96-110
mph) approaching a coastal area:
96 hours before landfall
At first, there are no apparent
signs of a storm. The barometer is steady, winds are light
and variable, and fair-weather cumulus clouds appear.
72 hours before landfall
Little has changed except that
the swell on the ocean surface has increased to about 6
feet and the waves come in every 9 seconds.
48 hours before landfall
The sky is now clear of clouds,
the barometer is steady, and the wind is almost calm. The
swell is now about 9 feet and coming in every 8 seconds.
36 hours before landfall
The first signs of the storm
appear. The barometer is falling slightly, the wind is
around 11 mph, and the ocean swell is about 13 feet and
coming in 7 seconds apart. On the horizon, a large mass
of white cirrus clouds appear. A hurricane watch is
issued, and the areas with long evacuation times are give
the order to begin.
30 hours before landfall
The sky is covered by a high
overcast. The barometer is falling at 0.1 millibar per hour,
winds pick up to about 23 mph. The ocean swell, coming
in 5 seconds apart, is beginning to be obscured by wind
driven waves, and small whitecaps begin to appear on the
ocean surface.
24 hours before landfall
Small low clouds appear
overhead. The barometer is falling by 0.2 millibars per
hour, the wind picks up to 34 mph. The wind driven
waves are covered in whitecaps, and streaks of foam
begin to ride over the surface. Evacuation should be
completed, and final preparations made by this time.
18 hours before landfall
The low clouds are thicker and
bring driving rain squalls with gusty winds. The barometer
is steadily falling at half a millibar per hour and the winds
are whistling by at 46 mph. It is hard to stand against the
wind.
12 hours before landfall
The rain squalls are more
frequent and the winds don not diminish after they depart.
The cloud ceiling is getting lower, and the barometer is
falling at 1 millibar per hour. The wind is howling at
hurricane force at 74 mph. The sea advances with every
storm wave that crashes ashore, and foam patches.
6 hours before landfall
The rain is constant and the 92
mph wind drives it horizontally. The barometer is falling
1.5 millibar per hour, and the storm surge has advanced
above the high tide mark. The sea surface a whitish mass
of spray. It is impossible to stand upright outside without
bracing yourself.
1 hour before landfall
The rain becomes heavier. Low
areas inland become flooded. The winds are at 104 mph,
and the barometer is falling at 2 millibar per hour. The
sea is white with foam and streaks. The storm surge has
covered coastal roads and 16 foot waves crash into
buildings near the shore.
Landfall
The eye of the storm: Just as the storm reaches its
peak, the winds begin to slacken, and the sky starts to
brighten. The rain ends abruptly, and the clouds break and
blue sky is seen. The barometer continues falling at 3 millibar
per hour and the storm surge reaches the furthest inland.
The winds fall to near calm, but the air is uncomfortably warm
and humid. Huge walls of clo9ud appear on every side,
brilliant white in the sunlight. At this point, the barometer
stops falling and in a moment begins to rise, soon as fast as it
fell. The winds begin to pick up slightly and the clouds on the
far side of the eye wall loom overhead.
