This is CNBC's Morning Squawk newsletter. Subscribe here to receive future editions in your inbox. Good morning. America's favorite groundhog, Punxsutawney Phil, saw his shadow this morning, meaning we're in for six more weeks of winter. After the recent string of cold temperatures, I can't say I'm surprised. Stock futures are sliding this morning. The three major indexes are coming off a losing day. Here are five key things investors need to know to start the trading day: The three major