Kurt Feltenberger wrote:

 >...what has me intrigued is what would happen
 > if the ability to control the weather was suddenly lost?

There will be inertia in the system.
Planets are big, and their atmosphere-ocean-land systems are big too.

So the end result (overshoot, damping, increasing chaos) depends on what
the control system actually affects - at typical Traveller tech levels,
altering the average orbital distance or axial tilt of a planet is not
an option, for example.

The basic parameters that can be tweaked are:
- instellation - sunshades to reduce irradiance or orbital mirrors to
increase it in areas.
- albedo - frothing the surface of oceans to reflect light into space;
dusting ice caps with soot to increase absorption; altering cloud cover
(can either enhance or decrease reflectivity); seeding the stratosphere
with sulfate aerosols to increase albedo.
- greenhouse effect - add/subtract substances to block/enhance outgoing
infrared emission. Can be done at different rates: ocean fertilisation
and planting trees relatively slow (years-decades, may also affect
albedo); enhancing carbonate formation (weathering reaction) very slow
(centuries-millennia).

I think the 'advanced' version has a very elaborate sensor network that
allows for real-time planetary monitoring on a sub-kilometer scale.

What parameters are adjusted depend on the local star's spectrum (redder
stars - more infrared, with implications for albedo), atmospheric
density, hydrographics, and the ability of the local economy to dedicate
resources to the effort.

Richard Aiken wrote:
 > From what little I've read, practical weather control would most
 > likely consist of precision crafting of "wild" weather patterns
 > using orbital microwave lasers. Applying heat at *just* the right
 > time and place and in the correct amount could be used to start,
 > stop and even steer weather patterns.

There's a real scale problem with this concept.
Condensation of water vapor to cloud and rain releases a *lot* of heat,
ignoring the baseline heat content of the air.
Typical tornado energy is on the order of 275 gigajoules with power
output of 1.7GW for a 100m funnel; the biggest events can contain almost
1000x more energy with 60x bigger power out in the lowest 100m (kilotons
TNT equivalent).
A good-going thunderstorm releases petajoules of heat (megatons TNT
equivalent).
Hurricanes, cyclones and typhoons are bigger still: exajoule scale with
terawatt level power outputs
(thousands of megatons TNT equivalent, with power outputs comparable to
a big fraction of global electricity production).

You are better off perturbing packets of atmosphere before they become
unstable. The problem is there's no good way of picking the right chunk
in terms of size and position.
Weather is chaotic.

Rob O'Connor