@whoa: She was attempting to stop the forest from attacking. It was part of some system link to their enemy The Future. The forest become a semi-conscious weapon that could adjust its attack to an enemy. Storm created some type of natural heat attack to stop it because plants would be sensitive to the extreme heat (dehydration, destruction of chloroplasts and of course a brush fire) that could destroy the plant mass that was attacking them.
She could also take out massive amounts of his human militia forces with a massive heat wave.