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

Pat Blazek shields himself from the snow and wind with an umbrella as he competes in a disc golf tournament Sunday, at Aggie Greens in Fort Collins, Colo. Snow is expected to fall through Monday, with highs reaching the sixties later this week. Erin Hull / AP

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Good morning, and happy Monday. Here are some of the stories we're following today:

1. Boko Haram leader says he will exchange girls for comrades

In a video recording obtained by Agence France-Presse, Abubakar Shekau says he will free more than 200 schoolgirls, kidnapped four weeks ago, on return for militant prisoners. The girls are featured in the latest video, in which the terrorist leader claims the young captives have converted to Islam. Hostage experts from the U.S. are expected to travel to Nigeria along with aid from Britain, France, China and Spain. Read more in NEWS.

2. Tornadoes hit the Plains, Snow builds in the Rockies

Monday's tornado threat spans from Minnesota into Missouri. Powerful thunderstorms produced tornadoes across Nebraska and Iowa on Sunday, causing damage to homes and businesses. Meanwhile, Denver was clearing a foot of snow from the roads and the mountains of Wyoming got double that. Read more in WEATHER.

3. Clippers owner Donald Sterling claims remorse

"I caused the problem. I don't know how to correct it,” Donald Sterling told Anderson Cooper on Sunday night, in apparent remorse for his racist comments, although he allegedly sings a different tune in recordings leaked last week. Sterling's estranged wife, Shelly, said the Clippers will belong to her, if her hubby is ousted, but the NBA says if one goes, they both go. Read more in SPORTS.

4. Rams: No guarantees for Michael Sam

Michael Sam was just drafted Saturday, but St. Louis Rams coach Jeff Fisher is already saying he'll cut the defensive end if he’s not one of the best 53 players on the roster. “[W]e picked him within the process and we’re going to reduce this roster within the process,” Fisher said of the first openly gay player drafted in the National Football League. Fisher might face scrutiny if the cut does happen, but seventh-round picks are routinely cut by the teams that drafted them. Read more in SPORTS.

Meanwhile, Sam is already out to prove doubters wrong:

5. Shots ring out at referendum in Ukraine

Ukrainian national guardsmen fired on a crowd Sunday in eastern Ukraine, where voters were lining up for a disputed referendum on whether to split from the rest of the country. An Associated Press reporter said he saw two motionless people on the ground after the shots. The ballots seek to declare the Donetsk and Luhansk regions separate from the rest of the country. Read more in NEWS.

… What’s trending today?

Barbara Walters graced the Weekend Update desk on Saturday Night Live this weekend to celebrate her retirement and the highlights of her career — not the real ones, of course, but the best impersonations of "Baba Wawa" on SNL over the years. From one anchor to another, Walter's advice to Cecily Strong was to make people cry, not laugh. Next Saturday's Weekend Update may just have a different tone.