Altimeter settings are contoured
dark green every tenth (.1) of an inch of Hg (these probably more accurately depict the pressure field for this region than isobars corrected to mean sea level would). Isotherms are contoured red every 4 °F - I did not attempt contouring over the Great Lakes other than for continuation of those over land. Data was plotted differently than the standard method so that the map would be as least cluttered as possible with sufficient data for good contours. Present weather symbols were plotted where sky cover typically is, with last 3 digits of altimeter setting above and Fahrenheit temperature below. Please be aware that numbers 990, 980, etc. refer to inches of Hg, not mb.The main feature is a 29.46 in. Hg cyclone centered just W of Indianapolis, IN. Many features are present. I drew a cold front extending primarily Sward from it, corresponding well with both a wind shift and sharp temperature boundary along it as analyzed. Consistent winds from the W or WNW were behind the front. 4 trofs are analyzed - 2 extending WNWward from the cyclone center, one E of it, and a quite small one SE. The WNW ones were likely a new cold front developing behind the system. I analyzed for this because of the wind shift evident, and abundant snow N of it. The E one was perhaps a developing warm front - a hint of the much stronger feature there at 850 mb. The SE one was perhaps another warm frontal boundary of sorts developing, corresponding well with the temperature maximum over E KY. A strong ridge was evident across the Appalachians. Corresponding with the sharp temperature minimum, this is called cold air damming. The mountains block rather weak but persistent surface winds from a general NEerly direction. Many smaller features are drawn. A broad high pressure ridge is directly SW of the cyclone center. What about the many smaller and weaker features such as the hints of a trof over NE WI & NW MI, central MI, or the ridging over W WI? I'm not certain these are real features, though the data supports them. A sea level pressure analysis (not shown) has hints of similar features. If you can read that data, you can see that although I interpolated well where possible, this would be unrealistic at a few places - especially Duluth, MN where a 30.36 reading was surrounded by those approximately .10 less.
Precipitation is typical of that associated with a cyclone - persistent snow with some rain further S at locations directly N of the cyclone and between the trofs WNW & E from it, a band of rain and showers along the cold front, and more scattered rain and showers in the warm sector. Some persistent rain was at the locations of cold air damming - some quite heavy. The rain/snow boundary is not where temperatures are 32 °F, but about mid 20's at most places because warmer air was being advected aloft. Freezing rain was observed at many locations between.
You may notice the general tendency of winds to behave as stated - circulating counterclockwise
around the cyclone with a component across the quasi-pressure contours toward the Low, and
strongest where they are most closely-spaced.
Text and embedded image are copyright of Joseph Bartlo, though may be used with proper crediting.