What's causing Chicago's mild weather?

CHICAGO (WLS) -- Many Chicagoans are enjoying the recent warm temperatures - some of which have reached almost 30 degrees above normal. But what's causing this?

ABC7 Meteorologists Phil Schwarz and Troy Christensen say current weather conditions throughout the U.S. are a signature of the El Nino phenomenon, as mild temperatures have hit the Midwest and rain/snowfall has hit the west.

WHAT CAUSES EL NINO?

Temperature anomalies causing warmer water around the equator off the Central and South American coasts transfer into the air, altering our weather patterns. The change creates a strong subtropical jet racing across the southern part of the U.S., bringing lots of rain (and in this case, snow) to those areas. This causes the polar jet to be trapped up in Canada, resulting in warmer temperatures in our area.

The pattern that is underway will likely be one of the strongest El Nino situations in the last 50 years.

Almost all noteworthy El Nino systems have resulted in mild winters for Chicago - and so far, this year seems no different.