Tyson entered in relief after Traci Tawney walked two batters to open the inning, including an intentional pass for UA home run leader Lovie Jung. Tyson walked Mackenzie Vandergeest before Coburn's homer.
UA first baseman Shelly Shultz won in relief in her first-ever pitching appearance. She threw two-plus innings and held UW to only one run on four hits.
The game was the highest scoring game in UA history, eclipsing a 29-0 victory over Bowling Green in 2001. The Husky scoring output is also an opponent high.
Arizona finished the regular season 50-5 and 19-2 in league action and is an expected top seed in the NCAA tournament as the automatic qualifier from the Pac-10. UW finished 42-14-1 overall and 9-12 in conference play for fifth place. Washington is a likely at-large selection for the NCAA tournament.
A number of rallies in the game saved UA from losing their first doubleheader since Washington won two over the Cats on May 11 last year, also the final day of the regular season.
The Huskies had 34 hits on the night while Arizona collected a more modest 26.
Jaime Clark's two-run home run staked the Huskies to a 2-0 lead in the first inning of the nightcap.
UA took the lead with one hit off UW starter Ashley Boek in the bottom of the inning. Three players walked, and Jackie Coburn snaked a two-run double down the rightfield line to tie the score. After reloading the bases with a walk by Erin Palomarez, Mackenzie Vandergeest beat the throw to home on Lisha Ribellia's fielder's choice to give UA the lead, 3-2.
It was short-lived, as the Huskies batted around in the second. Aimee Minor led off the UW second with a double, and scored on an RBI single by Amanda Oleson to tie the game. Then after a single by Rita Roach, Clark singled in Oleson to re-gain the lead, and Kristen Rivera lined a three-run home run to make it 7-3.
Arizone fought back, cutting it to 7-5 on a two-run single by Jackie Coburn in the bottom of the inning. But Washington poured it on with a three-run fourth to take a 10-5 lead, but UA put together a nine-run rally in the bottom of the inning, keyed by three-run home runs by Crystal Farley and Jackie Coburn.
Washington scored six runs in the top of the fifth inning, sparked by Rivera's second home run of the game, a two-run shot, and a two-run single by Minor to post a 16-14 lead. UA went to its bench to use first baseman Shelly Shultz in the pitching circle for her first collegiate appearance to record the last out of the inning.
Arizona tied the game at 16-16 in the bottom of the inning with an RBI single by Wendy Allen and an unearned run on a throwing error by Washington's third pitcher, Minor.
Erin Palomarez hit the first homer of her career with one out in the UA sixth to give the Cats the 17-16 lead, but in the top of the seventh a double by Kathy Fiske and an RBI single by Sarah Hyatt knotted the score.
Washington collected 13 hits including a couple of home runs, and whipped UA, 7-1, in the first game.
Huskies pitcher Tia Bollinger (24-9) held Arizona off balance and unable to make the most of its nine hits.
Kristen Rivera singled in an unearned run in the first to stake UW to a 1-0 lead after Roach hit a bunt single and reached second on a throwing error by UA pitcher Wendy Allen (12-2).
UA stranded three runners in the first, had runners on the corners in the third and had the bases loaded in the fourth but couldn't get a key hit off Bollinger (24-9). A diving catch by centerfielder Rita Roach in the sixth helped UW double off a UA runner at third to squelch another scoring opportunity.
Dena Tyson hit Allen's first pitch in the second inning over the left field fence to make it 2-0 for the Huskies, who also threatened with the bases loaded and two outs in the third but came up empty.
Shortstop Jaime Clark followed singles by Amanda Oleson and Rita Roach with her 13th home run of the year to make it 5-0 in the top of the fourth.
Arizona got its lone run with a sacrifice fly by Jackie Coburn after Lovie Jung singled, moved to second on a ground-out and to third on a wild pitch.
UW made it 7-1 with a two-run single by Fiske in the sixth inning.