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1. SNOWSTORM REPORTS

Storm total reports ending 3 PM Wednesday afternoon

2. CHICAGO’S CLOUDY PERIOD CONTINUES

After Wednesday we have experienced 6 consecutive days and 8 of the last 9 days with 0% sunshine

The longest stretch of sunless days here in December was 10 days on December 16 – 25, 1895—the longest sunless stretch in any month was 12 days running from December 29, 1991 to January 9, 1992. We now stand at 29% of possible sunshine so far this month. Normal for December is 40% (December and January are the cloudiness months of the year).

3. THURSDAY MORNING SETUP

Upper-level 30,000-ft jet stream flow—low-level/surface temp distribution. Also, projected movement of upper low-pressure center

  • Arctic air nosing into the northern/central Plains
  • Warm air depressed far south across Gulf of Mexico into Florida
  • Center of low pressure aloft will slowly move NE out of Iowa, crossing Wisconsin Friday and reaching into the Ontario province north of Lake Huron by Sunday
  • Leading edge of Arctic cold air will be pulled over northern/ central Illinois by WSW flow around the southern flank of the NE-ward moving low pressure
  • Embedded short-wave “disturbances” in the cyclonic flow around the upper low pressure will produce periodic snow showers here.

4. TORNADO OUTBREAK—MISSISSIPPI AND LOUISIANA

Wednesday morning and afternoon

As of 6 PM, 24 touchdowns had been reported in supercell t-storms, including in the city of New Orleans

5. MARKEDLY COLDER PATTERN TO LOCK IN AND BRING EXTENDED SPELL OF ARCTIC COLD NEXT WEEK

  • Full-day temperature departures from normal
  • Stunning week-to-week temperature change predicted—average among a suite of computer models