Hi Tee Emm,
There's an interesting explanation about why a shock wave can form early over the flight deck window / fuselage area from 42nd AIAA Aerospace Sciences Meeting and Exhibit 5 - 8 January 2004, Reno, Nevada:
http://www.aer.ita.br/~bmattos/downl...elage_aiaa.pdf
Page 3
"However, this apparently simple nature of the flow leads to complex consequences. As an example, the flow over the cockpit region can develop shock waves. The main reason behind this phenomenon is related to the shorter path that the flow follow from the standstill state in front of windshield to the freestream level at the beginning of the central fuselage. The shorter the path, the higher the speed of the flow along the cockpit curvature that eventually leads to shock wave formation depending on the fuselage shape and freestream Mach number."