Very Cold Forecast for Northern Wisconsin and Michigan
Today, I will be focusing on Northern Wisconsin and Northern Michigan for next Thursday at 1200Z.
The map above is an 850 mb GFS003 map that records temperature (degrees Celsius), heights (meters), and wind (knots) for 1200 UTC 13 November 2014. In northern Wisconsin and the upper peninsula of Michigan, the temperature will be -15 degrees Celsius at 850 mb. Winds will be from the west northwest at 20 knots. Does that mean that there is cold or warm air advection? Generally, if the wind barbs are parallel to heights, there is no temperature advection. However, look at the 850 QG temperature forcing (K s^-1) that measures temperatures (degrees Celsius) and heights (meters) [map below].
Areas to the northwest of the coldest temperatures in the continental U.S. may experience warm air advection, while areas to the southeast may experience cold air advection. How does that impact the temperatures at the surface?
Areas to the northwest may be colder than the southeast of the coldest 850 mb temperature points. Since the wind may be flowing from the northwest, areas to the southeast in lower Michigan is projected to have colder temperatures during the Thursday the 13th time frame.