The weather pattern on Wednesday will begin to change as an approaching upper level low over the southwestern U.S. weakens the subtropical ridge axis over Texas and the western Gulf. Isolated to scattered showers and thunderstorms will develop during the daytime hours. A Pacific cold front will move into the region Thursday spreading showers and thunderstorms over more of the area. Rainfall totals from Wednesday evening through Friday will be 2-4 inches with isolated amounts up to 8 inches possible. * WHAT...Flooding caused by excessive rainfall is possible. * WHERE...A portion of south central Texas, including the following counties, Atascosa, Bandera, Bastrop, Bexar, Blanco, Burnet, Caldwell, Comal, Dimmit, Edwards, Frio, Gillespie, Gonzales, Guadalupe, Hays, Kendall, Kerr, Kinney, Llano, Maverick, Medina, Real, Travis, Uvalde, Val Verde, Williamson, Wilson and Zavala. * WHEN...From Wednesday evening through Friday evening. * IMPACTS...There is a potential for life threatening flooding somewhere in the watch area. Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations. Creeks and streams may rise out of their banks. Flooding may occur in poor drainage and urban areas. Low-water crossings may be flooded. Extensive street flooding and flooding of creeks and rivers are possible. * ADDITIONAL DETAILS... - Rainfall totals of 2-4 inches with isolated amounts of 8 inches are possible. - Some locations that may experience flooding include... San Antonio, Austin, Round Rock, New Braunfels, Cedar Park, Georgetown, San Marcos, Pflugerville, Medina, Schertz, Kyle, Del Rio, Eagle Pass, Seguin, Cibolo, Kerrville, Converse, Universal City, Taylor and Uvalde. - http://www.weather.gov/safety/flood