Mobile Bay Response To a Strong Autumn Cold Front Passage

Mobile Bay is a shallow embayment in Alabama bordering the northern Gulf of Mexico. A cold front passage during October 2000 decreased air temperatures from 27°C to 9°C and was accompanied by winds from the north in excess of 16 m/s. The winds generated a significant water level decrease throughout Mobile Bay over a three-day period. Water level decreases occurred in the northern end of Mobile Bay (0.73 m), at the southern end of the Bay (0.27 m), and on the Gulf of Mexico shelf (0.30 m). Winds from four meteorological stations and water levels from six tide stations were low pass filtered. The low frequency response of water level to the winds accompanying the cold front passage was analyzed. The amount of water level change in the Bay was related to the location of the tide station. Correlations between the water level and northerly component of the wind were high and the correlations between the individual water level stations indicate that the water was transported southward over 12 hours. The analysis is consistent with a sustained northerly wind blowing down the axis of Mobile Bay and lowering water level at all locations within the Bay. The water exits through the Mobile Bay Ship Channel and flows across the inner shelf. Satellite-derived sea surface temperatures show the plume moving southwestward over a six-day period