SEATTLE — Rain postponed the first game of UT Arlington’s weekend baseball series at Seattle University on Friday, forcing a doubleheader Saturday, weather permitting.UTA (20-16 overall, 9-3 Western Athletic Conference) is tied for first place in the WAC entering today’s 2 p.m. series opener. Game 2 is scheduled to follow.Brad Vachon (4-2, 2.48 ERA) is scheduled to start Game 1 for UTA. Zach Thompson (4-2, 5.05) will start Game 2. Seattle is 13-22 overall and 3-8 in the WAC.UTA and Seattle are meeting in baseball for the first time. The Mavericks, who traveled 1,700 miles, are also playing in the Pacific time zone for the first time in baseball program history.