Tempest Breath

Type: Metabreath
Source: Draconomicon

You can make your breath weapon strike with the force of windstorm.
Prerequisite: Str 13, breath weapon, Power Attack, size Large or larger.
Benefit: When you use your breath weapon, in addition to its normal effects, creatures in the area are affected as through struck by wind effects. The force of the wind depends on your size, as indicated below. For the effects of high winds, see Table 3-24 on page 95 of the Dungeon Master's Guide.

Dragon SizeWind Force

Because your breath weapon has an instantaneous duration creatures ignore the checked effect unless they are airborne (in which case they are blown back 1d6x5 feet).
When you use this feat, add +1 to the number of rounds you must wait before using your breath weapon again.