As the upper air pattern adjusts, with the jet stream flow over the Mississippi and Ohio valleys becoming more southwesterly, strong southerly surface winds will persist over northern Illinois into the middle of the week ahead. The resulting warming trend will see temperatures average some 8° above normal during the next seven days. These mild readings along with evaporation-enhancing gusty SW winds will combine with fog, light rain and drizzle tonight and Monday, and eventually a steady rain Tuesday, to gradually eliminate this area’s snow cover. Just a week ago, snow on the ground was extensive and over a foot deep in the western suburbs.
As the SW jet stream flow here strengthens, the West Coast will experience an enhanced NW flow aloft that will steer a series of northern Pacific frontal systems southeast, initially hitting the coastline with frequent periods of rain and then snow at higher mountain elevations inland.
--By Paul Dailey, WGN Weather Center Meteorologist
