31. A gelid air mass over southern Canada will push south into the Plains. 32. The cold air mass will extend east to the Appalachian mountains. 33. Scattered thunder will develop in the unstable air mass in the Deep South. 34. Isolated afternoon thunder is possible where the two starkly contrasting air masses intersect. 35. High pressure near Chicago represents the center of a pleasant midsummer air mass . 36. This could be partly due to two air masses coming together. 37. Clouds and spotty showers will accompany a cool air mass across the Northwest. 38. Scenes at his open-air Mass suggested that was a tall order. 39. That collision of conflicting air masses usually causes particularly rambunctious storms in California. 40. In between lay the boundary between to starkly different air masses .
