I found this when I recalled that in the 60s some seeding experiments were done to try to weaken hurricanes.

The National Hurricane Center notes that a hurricane releases heat energy at a rate of 50 trillion to 200 trillion watts. (trillion here is used in the U.S. and French sense: a number followed by 12 zeros) This is the equivalent of a 10-megaton nuclear bomb exploding about every 20 minutes.

Regarding the use of bombs:

Q: Wouldn't a huge bomb weaken a hurricane? If they are worried about radioactivity, they could use powerful fuel-oil bombs.

A: A bomb or bombs would be a dead end since the amount of energy a hurricane is releasing and the size of its circulation would make any bomb, including the largest nuclear bomb, seem more futile than trying to stop a charging elephant by throwing a ping-pong ball at it. As noted above, hurricanes release tremendous amounts of heat energy. In fact, since hurricanes are "heat engines" that depend on the temperature contrast between warmth at the ocean surface and cold air aloft, we could wonder whether the heat from any kind of bomb would actually add to the storm's natural heat supply, making the storm stronger. Trying to heat the upper atmosphere with bombs, to lessen the heat contrast, would be like trying to heat the city of Minneapolis in January by opening the windows of a house.

Regarding the 60s experiments that I recalled:

Q: What happened to the idea of seeding hurricanes to weaken them?

A: During the 1960s the U.S. Navy and the National Oceanic and Atmospheric Administration (NOAA) tried a more sophisticated way of making hurricanes weaker. This research was known as Project Stormfurry. The basic idea was to seed clouds just outside the eye wall with silver iodide. The silver iodide, which is widely used in cloud seeding, encourages supercooled water - water that's colder than 32 degrees F but is liquid, not ice - to freeze. This releases latent heat, which would make the clouds grow, stealing some of the humid air that's helping the eye wall clouds grow and create strong winds.

This seemed to work with Hurricane Beulah in 1963 and Hurricane Debbie in 1969. But, scientists had no way of knowing whether these two storms would have weakened any way at that time. Hurricanes often weaken and then regain strength naturally. Also, since the 1980s researchers have found that most hurricanes don't have enough supercooled water for seeding to work.

Concerns were also raised that the experiments could make a storm change course, hitting some place that it otherwise wouldn't. The experiments did increase hurricane knowledge and also led to the purchase of the two WP-3 airplanes that NOAA still uses for hurricane research and tracking.

Imagine the worldwide reaction if we dropped silver oxcide into Katrina and it veered off and hit Mexico. It wouldn't matter whether or not it worked.