ATC Issue All Types; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Flight Crew Requested ATC Assistance / Clarification; Flight Crew Took Evasive Action
ATC Equipment / Nav Facility / Buildings; Weather
On departure at 16;000 FT on a heading of 240 we were handed of to JAX Center. We were unable to contact JAX Center due to frequency congestion. After trying several times to contact JAX Center we were forced to deviate from our assigned heading of 240 to a heading of 180 due to a level 5 thunderstorm off the nose. We had attempted to declare an emergency but were unsure that the controller ever heard it. After some time the controller handed us off and we turned back on course.
Air Carrier pilot was unable to contact Center during climb out to deviate for weather due to frequency congestion. A deviation was initiated before communication is established.