On the evening of September 10, 2014, a large frontal system was moving across the Great Lakes region, centered on northern Michigan. A warm front extended eastward into Maine, and a cold front trailed southwest from the low pressure area into Texas. To locate these fronts, we look for contrasts in air mass temperature. For example, in the Dakotas we see 40s and 50s, while the eastern quarter of the United States is dominated by 70s and 80s. To narrow this zone down, we always place the front on the warm side of temperature contrasts.
展开▼
