ELWOOD, Ind. — At some point Sunday night, Caleb Dunnichay sent a simple text message to his younger sister, Mary Beth.

“I think you’re just showing off now,” it read.

He was joking, but who’s to argue?

Mary Beth, a senior at Elwood High School and the United State’s youngest Olympian in 2008, won her third national title Sunday at the USA Diving Winter National Championships in Iowa City.

As outstanding as that feat is in and of itself, consider this:

The title came less than 24 hours after Dunnichay set an IHSAA sectional record with 519.65 points at Hamilton Southeastern.

She and her parents left immediately after the sectional and arrived in Iowa City around 10 p.m. central time Saturday night.

Dunnichay reported to the pool at the University of Iowa at 7 a.m. and took one practice dive before the competition.

Then she and Ohio State’s Katherine Bell — who practiced together for two days two weeks ago in Indianapolis and hadn’t dived together for five days prior to Sunday — rallied from a third-place finish in prelims to win the women’s synchronized national crown with 283.20 points.

Caleb Dunnichay won a state title at Elwood in 2004 and later competed for Auburn and Notre Dame. He isn’t easily impressed, but that can be added to Mary Beth’s list of weekend accomplishments.

“It’s pretty impressive,” he said. “She’s worked really hard at this, and it’s good when it pays off like this.”

It’s a week that won’t soon be forgotten in the Dunnichay household.

Mary Beth began it with that third-place finish in the prelims Monday in Iowa City. She and her mother, Marian, had their stay extended after that competition by a blizzard that dumped 18 inches of snow on Iowa.

“We literally couldn’t see out the window at the hotel at all,” Marian said.

Hoping to make it back in time for the end of the school week, mother and daughter rushed back from Iowa City at 5 p.m. Wednesday. They saw “hundreds” of cars and semis that had slid off the road as they made the trek back toward Indiana. But by waiting until Wednesday evening, they missed the worst of the road conditions.

They arrived in Elwood on Thursday morning at 2 a.m. only to find school was still out because of the ice storm that hit central Indiana.

On Saturday, the family packed for Noblesville and Mary Beth’s first sectional competition. For the second meet in a row, she set a pool record. But she failed to meet her own exacting standards.

“I didn’t dive amazing,” she said. “I just dove OK. But that’s alright because that’s not where I need to do my best.”

Mary Beth’s goal was only to survive and advance. Today she’ll compete at the IHSAA diving regional in Fishers. A top-eight finish there will qualify her for the state finals Saturday in Indianapolis.

“There’s not really a doubt in my mind she’s going to qualify,” Caleb said.

That would set up a big Saturday for the family. Caleb will be honored during the state meet as part of the 2011 Indiana Swimming and Diving Hall of Fame class.

“I think it’s awesome,” Mary Beth said. “He had his state moment. Now he’s going into the Hall of Fame, and it just so happens to be the year I’m trying to go to state.”

That event still likely will take a back seat to Sunday’s performance.

Marian was concerned enough about her daughters’ chances that she and husband Ned sat far away from the diving well instead of their usual spot with the other parents.

“I was nervous,” she said. “Other people might not understand it, but I don’t think anything is going to come easy.”

When Mary Beth stepped onto the tower for the first time since Monday, she felt pain in her surgically repaired shoulder. The impact from the 10-meter board obviously causes far more trauma on the joint than it does from the 1-meter springboard.

So she took just one warm-up dive.

“My shoulder was hurting me a lot,” Mary Beth said. “So I decided I didn’t need to take that much impact.”

Mary Beth’s regular synchro partner, Haley Ishimatsu, skipped the winter nationals to focus on her studies at Duke. So Mary Beth and Bell didn’t know what to expect Sunday.

But their list clicked from the opening dive, and they came home with a surprising win.

The odds against Mary Beth winning both events — in two completely different formats — on back-to-back days were astronomical. And the family still is having trouble putting their feelings into words.

“I don’t know if it’s really sunk in yet,” Marian said. “I haven’t even seen the medal yet.”

Given all she had to overcome with double duty, the heavy travel and an unfamiliar partner, Mary Beth said this national title probably will hold a special place in her heart.

But she’s not ready to celebrate anything just yet.

She’s looking forward to focusing solely on the 1-meter springboard this week and fine-tuning her list for the state finals.

No rest for the weary.

“We’ll sleep later,” Marian said. “There’s a lot worse things to be losing sleep over. We just want to see Mary Beth go as far as she can.”