Undular bore over the Gulf Coast region
GOES-12 visible channel images (above; Java animation) revealed an undular bore that was propagating southeastward across the Gulf Coast region of the US on 11 April 2007. This feature was aligned along a pre-frontal trough axis that was located ahead of an advancing cold front. A closer view of the southwestern end of the bore (below; Java animation) shows the fine wave cloud structure as the feature moved over the Gulf of Mexico (the wave train contained as many as 15-20 individual, narrow “roll cloud” bands). Rawinsonde data from Corpus Christi and Brownsville Texas showed that a very pronounced temperature inversion was present in the 1200-2300 ft (360-700 m) layer above the surface, which likely acted as a ducting mechanism for the bore; GOES-12 10.7µm InfraRed (IR) imagery exhibited fairly warm (+12 to +16 C) brightness temperatures in the area of the bore clouds, suggesting that those cloud features were at or below the top of the inversion. Note how the northward-moving marine layer cloud features that were present offshore appeared to dissipate with the passage of the undular bore. A similar case was seen in that same general region on GOES-10 rapid-scan imagery on 19 March 1998.
