To find out what the local time at any model times, you need to know how far ahead or behand GMT your local time is. 0 degree is at Greenwich, England.
Positive longitude is eastward from Greenwich till dateline.
Negative longitude is westward from Greenwich till dateline. Positive latitude is in the northern hemisphere, and negative latitude is in the southern hemisphere. When comparing model winds with station observations, winds need to be rotated to earth coordinate. MM5 modeling system programs use array indices I, J, and K, where I is in y direction, J in x direction, and K in z direction.