The swallows have returned to Capistrano, the buzzards have arrived in Hinckley, Ohio and we're on the look-out for the purple martins in Baton Rouge. Welcome to the first day of Spring...The official time for the start of Spring is determined by the earth's motion around the Sun. Sky and Telescope provides some interesting items on the start of Spring. For the Northern Hemisphere it's defined as the moment when the Sun passes over Earth's equator on its journey north, officially called the vernal equinox. The word, equinox, originates from the Latin for "equal night." Day and night are not exactly 12 hours long at equinox for a couple of reasons. Sunrise and sunset are determined when the Sun's upper edge, not the center, crosses the horizon. The second reason involves the Sun's position near the horizon, causing refraction by the Earth's atmosphere which shifts its position slightly upward. Mother Nature set the alarm clock for 6:02 AM this morning, officially launching spring. The start of spring introduces windy weather in many sections of the United States and more kite flying. Another tradition for the National Weather Service includes informing and preparing the public for flooding. As we have  incurred devastation flooding in the northern sections of the state, Ascension, Livingston and Tangipahoa Parishes experienced the same last weekend.  This week is Flood Safety Awareness Week and the Service provides daily educational topics. Flooding in the United States and its territories occur every day of the year, causing more damage than any other weather-related event. Over the past 30 years flooding caused 95 deaths per year, on average, and eight billion dollars in damage.  As our residents know, rainfall on the watersheds of the Amite, Comite, Tickfaw and Tangipahoa River Basins in excess of six inches rapidly increases river levels, placing residents at risk.