CL604 FLC ENCOUNTERS SEVERE TURB DURING CRUISE.

Narrative

PRIOR TO DEP; THE CAPT AND I DISCUSSED A POSSIBLE RADAR ISSUE WHERE THE ACFT WAS HAVING DIFFICULTY DEPICTING WX. ON THE GND; WE WERE ABLE TO DEPICT A CELL OFF THE END OF RWY 15L; WHICH WAS THE DEP RWY. AFTER DEP; WE NOTED THAT THE RADAR WAS NOT DEPICTING PRECIPITATION AND WE VISUALLY CIRCUMNAVED SEVERAL ISOLATED TSTMS. WHILE ON J29; WE ENTERED INTO A HIGH ALT HAZE LAYER AND SHORTLY THEREAFTER I NOTED A LARGE TSTM DIRECTLY IN FRONT OF US AND PROMPTLY NOTED IT TO THE PF. SINCE OUR VISIBILITY WAS VERY LOW AND WE HAD VERY LITTLE TIME TO REACT; THE CAPT HIT THE SYNC BUTTON AND MADE A HARD R TURN FOR WX AVOIDANCE. WE ENTERED THE CELL AS ITS SMALLEST POINT THROUGH WELL ABOVE OUR CRUISE ATTITUDE. WE IMMEDIATELY EXPERIENCED SEVERE TURB AND HVY RAIN YET AT NO POINT WAS WX DEPICTED ON THE RADAR. AS A RESULT OF THE TURB; WE CLBED AS HIGH AS FL382 AND DSNDED AS LOW AS FL360. ATC NOTED THE ALTDEV AND I BRIEFLY TOLD HIM WHAT HAPPENED. IN MY OPINION; THIS INCIDENT WAS STRICTLY BECAUSE OF A BAD RADAR SYS IN THE ACFT.