That is a North American NA-36, BC-1, a North American NA-16 derivative, the predecessor of the North American T-6 Texan
Source: nationalmuseum.af.mil
Some observations that helped to determine the precise model:
The fuselage is covered with fabric. Later models used metal
The trailing edge of the rudder is rounded, later models had a straight rudder
The bottom corner of the rudder is squared, some other models are rounded (e.g BT-9)
The fuselage shows the crest of the USAAF's Technical Training Command:
Source: Picturing Meteorology
The aircraft belonged likely to Chanute Field Technical Training Command (Illinois), located some 200 miles south of Madison.