1. Wednesday morning—50mph+ low-level (2,500 feet above ground) jet noses into the Chicago area

• Low-level jet funnels warm moist unstable air into the Chicago area
  • wind gusts could reach 40 mph+ at the surface out of the SE
  • low-level turbulence likely for aircraft landings and takeoffs
  • heavy rains up to an inch during morning commute
• Severe storms possible Gulf coast states as day progresses
• Broad band of heavy rain in advance of cold front
• Heavy blowing and drifting snow north and west of low-pressure center — up to 12-plus inches in western South Dakota and Nebraska, eastern Wyoming and northeastern Colorado

2. Thursday morning—weather shifts east

• Low-level jet (LLJ) flows up east coast
  • wind gusts to 40 mph out of the south at the surface and low-level aircraft turbulence
  • heavy one-inch-plus rains parallel and to the east of the cold front
• Severe storms possible southeast Atlantic states and Florida
• Heavy blowing and drifting snow north of the low-pressure center; heaviest 12-inch-plus snows northwest of Lake Superior in Minnesota
• Chicago area— WSW winds bring colder air and occasional light snow and flurries

3. Tuesday afternoon snowfall/wind reports

North and west of developing low pressure center—high wind, snow and blizzard condition reports

4. Wednesday evening set-up

Upper level 30,000-foot jet stream flow and low level/surface temperature distribution

• Bitter arctic-source cold air rides north winds into central Plains
• With 140-mph southerly jet stream overhead, Chicago positioned in mild air— cold air just to our west
• Low pressure aloft drifting northeast out of Nebraska toward Wisconsin. The leading edge of arctic air will arrive here as the low center moves northeast of Wisconsin this weekend