E.D.G. asked me to post my reply to this question:

In EarthWaves 9537 you mentioned that we can actually see the
Earth's rotation speed up and slow down each day. Are you referring
to the actual rotation of the entire Earth or just individual
continents being temporarily shoved a little to the east or to the
west by a hurricane (a surface effect)?

I could see the rotation speed of the Earth changing if its shape is
changed a bit because a hurricane caused a large mass such as ocean
water or perhaps even land to move farther from the Earth's center.
It is difficult for me to picture how wind drag could directly
change the rotation speed though I am not proposing that this is not
possible.

You might consider posting the answer to that question to the
EarthWaves board and even expand on it a bit. Other people would
probably be interested.

My answer to E.D.G
Any transfer of energy is capable of changing the rotational
velocity of the earth. If a storm is moving against the rotation,
it creates a drag due to wind and currents which will slow the
surface of the earth down. if it is moving with the earth, but faster,
it will speed the earth up by a similar drag. The numbers were presented
in an earlier posting. The plate which is being dragged by the storm
will eventually transfer that change in rotational velocity to
the rest of the earth (usually this occurs fairly quickly). This
results in the change in the LOD, which can be either faster
or slower than average on any given day. Of course, other forces
can also change the rotational velocity - like tides, geomagnetic
storms, gamma bursters, and any other outside force. These changes
in LOD are not great, but are large enough to be measured.

It really is all a matter of conservation of angular momentum.
The angular momentum of the entire earth must be conserved. If
a storm contains angular momentum and dissipates as it passes
from ocean to land, that angular momentum is transferred to the
earth.

If a hurricane is moving against the motion of the earth, it is
transferring energy to the earth continuously through drag. When
the hurricane is no longer moving, the drag is eliminated and
the earth responds to other acting forces changes it's velocity
of rotation accordingly. Don't forget the earth is a heat engine.
Heat stored in the oceans can be changed to energy of motion in
winds, which is then changed to energy of motion of plates which
is then changed to energy of motion of the earth.