KNOW IT ALL: Monday's Top Stories at NBC News

A woman snaps a selfie in front of armed servicemen and their armored personnel carrier in the eastern Crimea's port city of Feodosiya.VIKTOR DRACHEV / AFP - Getty Images

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Good morning, and happy Monday. Here are five of the top stories we are following this morning at NBC News:

1. Oscar Pistorius trial begins

The prosecution opened the case in South Africa on Monday in which double-amputee Olympian Oscar Pistorius is charged with premeditated murder of his girlfriend. A neighbor testified she heard screams before the gunshots that killed Reeve Steenkamp on Feb. 14, 2013. Follow the trial here. Read more in NEWS.

2. '12 Years a Slave' wins best picture at the Oscars

Hollywood's biggest night was historic, as '12 Years a Slave' director Steve McQueen is the first black director to take home a best picture award. Host Ellen DeGeneres not only set out to deliver a fun show, but also sought to garner the most re-tweets ever with a star-studded-selfie. DeGeneres surpassed 1 million re-tweets, breaking the record — and Twitter for a bit. Read more in ENTERTAINMENT.

Here's Ellen's tweet heard round the world:

3. Midwest storm descends on Northeast

The snow, sleet, and ice that downed power lines and grounded flights in places like Chicago, Ohio and Indiana over the weekend made its way to the Northeast in time for Monday's commute, as promised. More than 2,000 flights were cancelled by 5 a.m. Monday, and meteorologists don't anticipate the storm will move completely off-shore until 10 p.m. Read more in NEWS.

4. Ukraine says Russian troops are getting closer

Ukraine said Russia was building up armored vehicles on a thin body of water near the Ukrainian region of Crimea after President Vladimir Putin over the weekend gained approval to use military force in Ukraine. Secretary of State John Kerry will travel to Kiev on Tuesday. Read more in NEWS.

5. And G-8 might turn into G-1

Canada, France, Germany, Italy, Japan, the United Kingdom and the United States denounced Russia's hostile takeover of Crimea on Sunday and said they won't prepare for the G-8 summit slated to take place in Sochi. British Prime Minister David Cameron also said Sunday that British leadership will stay away from another Sochi event, the Paralympics. Read more in NEWS.

… What’s trending today?

Jimmy Fallon held up his promise to Chicago Mayor Rahm Emanuel on Sunday and took a polar plunge into Lake Michigan in 20 degree weather ... while wearing his late night swag, of course.