A B757 IS DAMAGED BY HAIL AT FL370; 40 MI FROM A SET OF VISIBLE TSTMS W OF THEIR POS WHILE 50 MI N OF ORL; FL.

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IN CRUISE AT FL370; ENTERED MULTI-LAYERED CLOUD SYS; NOTHING DISPLAYED ON RADAR; ENCOUNTERED LIGHT TURB. WE PLACED SEAT BELT SIGN ON. A MIN OR TWO LATER TURB BECAME MODERATE SO WE MADE A PA ANNOUNCEMENT FOR FLT ATTENDANTS TO BE SEATED. ALMOST IMMEDIATELY THE TURB BECAME SEVERE; WITH HAIL HITTING ACFT. HAIL LASTED 15-30 SECONDS WITH ACFT ROLLING R TO 30 DEGS AND CLBING RAPIDLY TO 38000 FT AS AUTOPLT WAS DISENGAGED. THE HAIL SHATTERED THE FO'S OUTER PANE OF GLASS IN HIS WINDOW AND THE RADAR QUIT. THE RIDE THEN SMOOTHED OUT. WE DECLARED AN EMER WITH ZJX AND ASKED FOR A LOWER ALT. SINCE THE RADAR WAS NO LONGER FUNCTIONING AND TSTMS WERE OVER GEORGIA WE LANDED AT JACKSONVILLE ARPT. NO PAX WERE HURT. THE FLT ATTENDANTS COMPLAINED OF BRUISES AND STRAINS. AFTER LNDG WE DISCOVERED THAT ABOUT A FOOT DIAMETER SECTION OF THE RADOME WAS CAVED IN; THE FO'S SHATTERED WINDOW; THE LNDG LIGHT LENSES WERE BROKEN AND NUMEROUS SMALL DENTS IN THE LEADING EDGES OF THE WING AND ENG COWLING. THE ENG BLADES WERE OK. SUPPLEMENTAL INFO FROM ACN 437816: ENRTE FROM RSW TO ORD. TIME OF INCIDENT WAS XA45; 50 NM N OF ORL VOR ON J-53 AT FL370. OUR RADAR HAD INDICATED SEVERAL TSTMS TO THE W OF OUR POS (40-50 NM W) WHICH WE AVOIDED BY OUR RE-ROUTED FLT PLAN. ZJX HAD JUST CLRED US TO AMG (GA) VOR AND WE MADE THE 15-20 DEG L TURN DIRECT AFTER ENSURING OUR PATH WAS CLR VISUALLY AND WITH RADAR. THE RADAR SHOWED NO RETURNS. THE RIDE BEGAN TO DEGRADE AS WE DROVE INTO LIGHT CIRRUS CLOUDS. I DECLARED AN EMER AND RECEIVED CLRNC FROM ATC TO TURN 15 DEGS R AND DSND TO A LOWER ALT (INITIALLY FL330). BY THIS TIME THE RIDE RETURNED TO SMOOTH. WE COORDINATED WITH DISPATCH; MAINT AND LCL OPS; COMPLETED ALL CHKLISTS AND BRIEFS WITH FLT ATTENDANTS AND PAX. I BELIEVE WE OPERATED OUR RADAR IN ACCORDANCE WITH OUR SOP'S AND GOOD RADAR DISCIPLINE. IT IS POSSIBLE THAT WE HAD A WEAK RADAR OR THAT THE RADAR FAILED WITHOUT INDICATING A FAILURE CAUTION. IT IS ALSO POSSIBLE THAT THE TILT CTL WAS OUT OF CALIBRATION. IT IS ALSO POSSIBLE THAT OUR RADAR OVER-SCANNED A RAPIDLY BUILDING CELL (BUILDING AT 5000-6000 FPM) AND WE COULD HAVE OVERFLOWN IT OR NEAR ITS EDGE; BUT I BELIEVE A FULLY OPERABLE SYS WOULD HAVE GIVEN AN INDICATION. IT IS POSSIBLE THAT THE BAND OF HAIL WAS SO SMALL; THAT IT FAILED TO REGISTER; IN THE NORMAL MODE. IN THE FUTURE I WILL ALWAYS EXAGGERATE MY DOWN SCAN AND SWITCH MODES MORE OFTEN. I WILL ALSO ATTEMPT TO AVOID ANY FLT IN LIGHT CIRRUS WHEN BUILDUPS ARE WITHIN 80-100 NM BECAUSE THEN YOU ARE TOTALLY DEPENDENT ON A GOOD RADAR. I DO FEEL THAT OUR PREPARATION AND TRAINING AND OUTSIDE RESOURCES ASSISTED US AS A CREW TO ADEQUATELY DEAL SUCCESSFULLY WITH THE EMER DURING AND AFTER THE ENCOUNTER.