Cold Air Returns for St. Patricks Day

Everyone was overjoyed with the weather on Monday, March 16th. Chicago reached the degrees of 70 and everyone made sure to take a walk. The problem is that everyone is getting use to this weather but now for St. Patrick's day it went back down to 40 degrees. A cold front pushed south of the Canadian border on Monday. From there, it will slice through the East Coast and into parts of the South on St. Patrick's Day. Behind this cold front, temperatures will be 20-40 degrees colder than Monday. That said, temperatures in the Midwest will only fall back to levels more typical of mid-March.

Since last week, however, most of the U.S. has been under the influence of air masses that originate from either the Pacific Ocean – in some cases, the tropical Pacific – or the Gulf of Mexico. Naturally, this has combined with March's higher sun angle and longer days to bring a big warm up to much of the country. According to The Weather Channel storm specialist Dr. Greg Postel, part of the reason for this pattern shift has been a large cluster of thunderstorms, including several tropical cyclones, thousands of miles away over the southwestern Pacific Ocean.

Link:http://www.weather.com/forecast/national/news/colder-weather-pattern-change-spring-equinox-2015