“It’s going to be a great day, Seattle,” the weatherman began the Season 10 finale of “Grey’s Anatomy.” Little did he know, his predicted forecast for episode 24, “Fear (of The Unknown),” couldn’t have been any further from the truth.

Everyone began their Thursday morning on a semi-normal note: Cristina said her “not” goodbye to Owen and revealed she had to stop by the mall to run some errands; Derek and Meredith ate breakfast with Washington on their mind; Alex revealed he was getting a Batman-esque car and April told Owen she was pregnant! C’mon, I said semi-normal, guys.

But unlike those happy campers, not everyone started their day off on the right foot. Take Miranda for example... As soon as she walked into Grey’s Sloan Memorial Hospital she was greeted with terrible news: the budget was forcing her department to close. With steam shooting from her ears and nose the sassy surgeon attempted to debate the situation.

While Miranda fought for her division, fans found out whom Cristina had chosen as her replacement. Yep, it was the smarty-pants youngster! We could sense some strange energy between the two as the newbie asked whether or not Cristina would be lurking around Grey Sloan. Looks like this girl catches on quick!

But competitive nature was put to the side when the hospital learned of a possible terrorist attack on a Seattle-based mall. Oh yeah, we said mall. You know, as in the place Cristina was headed to buy a charger. This is the point of the finale we started to sweat.

After the anchor announced the terrible news, Owen and April started shouting orders out in hopes of preparing the hospital for the slew of victims about to be rushed in.

“We are fully equipped,” Owen said during a press announcement, thinking about Cristina. “If you lost someone stay clear of emergency entrance.”

After his plea, Owen rushed through the hospital full of screaming victims looking for a place to call his loved one. But of course Cristina’s phone was dead. Go figure.

The cameras then cut to a scene of all the victims entering the hospital, giving fans tidbits of information regarding how they were effected: One man’s eye was dangling from his head, a surrogate’s pregnancy was in distress, a couple was missing their son and those effected by the blast were sporting blisters on their bodies.

Unfortunately, not all those who survived the alleged terrorist attack were treated with respect and courtesy. You know, like the man officials thought were responsible for the explosion. While berating the young man with questions, he collapses. Meredith rushes the suspect to the OR but the badge-donning men tried to step in her way.

“I’m the boss in here. Get out of my way,” she demanded.

But our cheering only grew louder when we found out Cristina was alive and well! We wiped the sweat from our brow and continued to watch on. Without a second to lose Cristina started getting to work. And she wasn’t the only one. Leah Murphy, the recently fired resident, proved to be an asset when she arrived to the hospital to lend a helping hand.

As Grey Sloan attempted to take care of the victims, a journalist got in the way by spreading false reports -- like claiming there was an outbreak of radiation and that a potential attack on the hospital was to be feared. Furious, Owen stepped in to set the record straight. He kicked out the reporter, ending his false claims.

As her boyfriend make his TV debut, Cristina was taking care of patients – and Meredith.

Her twisted sister revealed that she was moving to D.C.

“I’m happy for you,” Cristina said with a hint of doubt. Meredith could tell there was a lack of sincerity. And we couldn’t help but wonder why Cristina would be anti-Washington.

Shortly after her run in with Meredith, Cristina found herself side by side with Alex. He too was planning on leaving Grey Sloan, which is when Cristina told him he was making a mistake. She recalled all his greatest moments, which he was surprised she remembered.

“You’re putting all that talent in the drawer,” she said, adding the compliment that he was a great doctor.

After the sentimental moment between former interns, reports revealed that the fear of a terrorist attack was actually a gas main explosion.

While most sighed in relief, April couldn’t help but have a meltdown in a closet. She revealed that she was scared to have a child in a world where terrorism was a first thought.

“I don’t think I could live in a world where my child could die getting a pair of shoes,” she said with tears rolling down her cheeks.

Her in-law calmed her nerves, explaining that it’s the fear that defeats you. Don’t let it defeat you, April!

Finally, Cristina admits something we knew all along: She doesn’t want to leave. As if her procrastination wasn’t blunt enough!

“I have to finish something here. None of it feels finished. You and I are not finished. I am not finished,” she revealed.

“This isn’t the end for you. There is no end point. You just have to go,” Meredith replied.

“I keep trying to but I don’t know to how just do it. You’ve got to help me, Mer,” she pleaded.

After wiping away Cristina’s tears, the two head out. Cristina says farewell to Derek, Bailey, Webber and finally Owen who she waves goodbye to through a surgical window.

Meredith then pushes Cristina into a cab. We’re actually surprised Bailey wasn’t the one to do so considering Webber just offered her Cristina’s seat on the board. Miranda couldn’t be more thrilled with her new position because guess what – that means her department is back open for business, baby!

Just as we figured, Cristina somehow ended back in Grey Sloan.

“I can’t go. We have to finish. We have to dance it out. That’s how we finish,” Cristina said our favorite line of the Season 10 finale. “You’re my person. I need you alive. You make me brave.”

The two then shake it out to Tegan and Sara’s “Where Does The Good Go.”

“You are a gifted surgeon with an extraordinary need. He’s very dreamy but he’s not the sun. You are,” Cristina said our second favorite line of episode 24, exposing why she wasn’t thrilled about Meredith going to Washington. She felt as if her bestie was being eclipsed by the ever so sexy McDreamy.

Meredith takes her friend’s advice and confronts Derek about her feelings.

“I think I need to stay here,” she said after refusing to sign the papers. “It’s not what I signed up for. You believe you career is more important than mine.”

“There’s nothing you can do here that you can’t do there,” Derek attempted to counter argue. But Meredith’s mind was clearly made up.

“I don’t want to. I live here. My life is here. I don’t want to leave,” she firmly stated. Sorry, Derek. She’s no longer that sweet intern so easily persuaded!

But the most shocking moment of the Season 10 finale was finding out just exactly who the “new Cristina” was. After her hectic day, she confronts Webber about being unable to make friends. She revealed the only reason she came to Grey Sloan is because her mother, who she never met due to being adopted, used to work at the very same facility.

Looking confused, Webber asks who her mom was.

“Ellis Grey. Did you know her?” she asked.

Guys, meet Meredith’s new half sister!

Episode 24 ended with Cristina and Shane in Switzerland. And with Yang leaving Alex her seat on the board. Looks like Season 11 will feature a duel between the Karev and Bailey!

What did you think of the Season 10 finale? Chime in with your thoughts in the comments section below.