phase of explosive deepening. By this time, gale-force winds extended to the north of the center and to the south. Ethel further intensified into a major hurricane, as it approached the Gulf Coast of the United States. Following a pass through the storm by a United States Navy reconnaissance plane, Ethel was declared a "severe hurricane" with winds reaching , equivalent to a modern-day Category 3 hurricane on the Saffir–Simpson hurricane scale. At the time these winds were measured, a barometric pressure of 974 mbar (hPa; 28.7 inHg) was recorded, the lowest in relation to the hurricane. However, shortly thereafter, cool, dry air began to entrain the storm, causing it to rapidly weaken. In a six-hour span, the storm suddenly weakened to a Category 1 hurricane, a decrease of . As Ethel neared landfall, forecasters within the United States Weather Bureau were unsure of the future track and intensity of the hurricane due to the unusual strengthening and weakening. Around 1100 UTC on September 15, the center of Ethel brushed the coastline of Plaquemines Parish, Louisiana with winds of . Continuing northward, the hurricane further weakened to a tropical storm as it was approaching the Gulf Coast of the United States. Shortly before 0000 UTC on September 16, Ethel made landfall in Pascagoula, Mississippi with winds of . Gradual weakening took place as the storm moved inland over Mississippi and by 1800 UTC on September 16, Ethel was further downgraded to a tropical depression. The remnants of the former hurricane continued moving towards the north-northwest before dissipating on September 17 over southern Kentucky. Preparations Prior to Ethel's arrival, adequate warning allowed roughly 12,000 residents along the Mississippi coastline to evacuate to shelters, set up at churches and schools. Along a stretch of the Gulf Coastline, all fishing villages fully evacuated to safer places. In Louisiana, at least 2,000 people had been evacuated from Grand Isle. Other towns were placed under emergency evacuations where Coast Guard boats were used to move residents to safer areas. Military aircraft were also moved from Keesler Air Force Base to other airfields across the country. Numerous schools and businesses were closed on September 15 in fears of a worst-case scenario, a storm with winds passing directly over Mobile, Alabama, a city of roughly 150,000 people. In Florida, the National Weather Bureau stated that preparations were not being undertaken fast enough nor as extensive as warranted.