The surface map from Thursday afternoon (below) shows a deep low pressure area moving from Kansas toward southeast Nebraska. This is the same low that produced heavy rains across southern Wisconsin and brisk east winds off Lake Michigan. A large area of strong southwest winds were located south of the low from the southern Plains into middle Mississippi River valley. When the low moved into Iowa this morning, the southwest winds apparently pushed the dust layer into southern Wisconsin.
More information is available from the Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin-Madison
*****The following was written by Scott Bachmeier of CIMSS (SSEC, UW Madison)
A significant blowing dust event was noted yesterday (10 April) over parts of New Mexico and Texas. There happened to be a timely overpass of the polar-orbiting Terra satellite at 17:20 UTC, and the Terra MODIS imagery acquired over the developing blowing dust plume helps to demonstrate the utility of the MODIS "cirrus detection" channel for detecting features such as blowing dust (this channel is very sensitive to airborne particles that are *efficient scatterers* of light, which includes ice crystals, dust, haze, or volcanic ash). I placed some examples of the MODIS imagery on our CIMSS Satellite Blog:
This case was also of interest since the dust plume was then advected all the way to northern Illinois and southern Wisconsin within a 24-hour period -- rumor has it that there were some public reports of "dirty rain" over far southeastern Wisconsin on the morning of 11 April...
A similar dust event is documented in following link from December 16, 2003
Jeff Craven, Science and Operations Officer