Another Heavy Snow Falls on December 18th and 19th, 2000
It sounds like a broken record but yet another potent winter storm developed over the Missouri valley on Monday December 18th, then moved across Indiana. Heavy snow fell for a period Monday evening and early Tuesday morning across northern Indiana...northwest Ohio and southern lower Michigan. Heavy lake effect snow began Tuesday morning in northwest Indiana and southwest Michigan and continued throughout the day.
A strong jet stream was once again responsible for developing low pressure at the surface over southern Missouri Monday morning. Heavy snow broke out across Iowa and then moved into Wisconsin and Illinois during the afternoon. As the low strengthened and an upper level disturbance began to approach the area Monday afternoon, snow began to increase across eastern Missouri and Illinois. In response to the upper system, the surface low began to move northeast and by Monday evening, it was located over north central Indiana. Moderate to heavy snow increased over northern Indiana and southwest lower Michigan Monday evening as this area became influenced by upper level divergence associated with a jet streak of 145 knots, or 167 mph. (A little jet dynamics here, but a jet streak is an area of higher wind speed that is embedded within the jet stream itself. The front, left quadrant of a jet streak, along with some other atmospheric dynamics, creates diverging air in the upper atmosphere. Atmospheric thermodynamics and physics implies that if air is diverging in the upper atmosphere, it must be converging in the lower levels and rising. Low level convergence and rising air creates deepening surface low pressure and enhances snowfall rates. This is probably more than you ever wanted to know about jet dynamics!!)
The surface low moved into northwest Ohio late Monday evening. The snow began to taper off around midnight as the low moved from northwest Ohio into Ontario Canada by Tuesday morning. Winds behind the low became northwest and lake effect snow began. Multiple bands were present across northwest Indiana and southwest Michigan Tuesday morning. A long, intense, impressive single band developed on the western side of lake Michigan Tuesday morning and can be seen in the early visible satellite pictures, extending from northern Lake Michigan to northwest Indiana. Surface pressure and wind streamlines have been superimposed onto the satellite and you can see a meso-low located over the southeast part of Lake Michigan. These meso-lows act to enhance snowfall rates with lake effect bands...generating snowfall rates of 1 to 2 inches per hour!
Meteorologists at NWS Northern Indiana issued a winter storm outlook Sunday December 17th at 200 pm EST, then issued a winter storm watch at 400 am EST Monday morning. The watch indicated the potential for 5 to 7 inches of snow Monday night, with additional lake effect snow Tuesday. A winter storm warning was issued for northwest Indiana and southwest lower Michigan at 330 pm EST Monday afternoon, calling for 3 to 7 inches of snow plus another 3 to 6 inches, plus locally higher amounts, with lake effect Tuesday. A winter weather advisory was also issued for the remainder of northern Indiana...lower Michigan and northwest Ohio at 330 pm EST Monday afternoon for 2 to 5 inches of snow and increasing winds on Tuesday.
Snowfall amounts ranged from 2 to 5 inches across the entire area between 600 pm Monday night and 800 am Tuesday morning with an additional 1 to as much as 8 inches of lake effect snowfall that fell during Tuesday afternoon and evening. Here is a Public Information Statement with snowfall reports from our observers.
These amounts have also been plotted on a map for easy viewing.
This story written by Sam Lashley and Todd Holsten
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