  In order to study the properties of $J/\psi$ (1S) in the deconfining medium,
we extend our previous formalism [Phys. Lett. B {\bf 656}, 45 (2007)] on
$J/\psi$ suppression at mid-rapidity using the colour screening framework. Our
formalism is more general as the complete rapidity, transverse momentum and
centrality dependence including $J/\psi$ suppression at forward as well as
mid-rapidity can be computed directly from it. Careful attention is paid to the
role of the medium's proper time in determining the locus of the screening
region where $J/\psi$ gets suppressed. Other important ingredients in the
calculation are bag model equation of state for QGP, the longitudinal expansion
of the QGP fluid obeying Bjorken's boost invariant scaling law and
non-sequential/sequential melting of $\chi_c$ (1P) as well as $\psi^{'}$ (2S)
higher resonances. Upon comparison with the recent data of PHENIX collaboration
on $J/\psi$ suppression at forward and mid-rapidity regions, we find that our
model shows a reasonable agreement with the data without incorporating any
sequential decay mechanism of higher charmonia states. Furthermore, we observe
a larger suppression at forward rapidity in our model which is again well
supported by the PHENIX data and also gives a hint that a scenario based on
directly produced $J/\psi$'s is preferable.
