AN ACR CREW REPORTS EXERCISING EMER AUTHORITY AND DEVIATING FOR TSTMS ON THE ATLANTIC WATRS TRACK IN THE N CARIBBEAN WITH NO ATC COMM.

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DURING CRUISE FLT ALONG RTE; APCHING ABE INTXN; TSTMS PRECLUDED NAVING OVER THE PRESCRIBED WAYPOINT. THIS WAYPOINT; ABC; WAS THE DESIGNATED EXIT FROM NORTH ATLANTIC WATRS AREA INTO ZMA'S NORTHERN CARIBBEAN SECTOR. PRIOR TO REACHING ABC; HF COMS WERE ATTEMPTED WITH ZNY IN AN EFFORT TO REQUEST AND RECEIVE DEV CLRNC PRIOR TO REACHING MIA AIRSPACE. HF COMS WERE UNSUCCESSFUL. THE CAPT EXERCISED HIS EMER AUTH AND DIRECTED A DEV AROUND THE TSTMS IN ORDER TO AVOID DAMAGE OR INJURY THAT MAY HAVE BEEN CAUSED. AS THE PLT AT THE CTLS; I EXECUTED THE DEV AND MANEUVERED THE ACFT TO RE-INTERCEPT THE PRESCRIBED AIRWAY COURSE/TRACK TO RESUME NORMAL FLT. DEV FROM TRACK RESULTED IN LATERAL DEV OF APPROX 5-6 NM FROM TRACK. THE CAPT UTILIZED ENRTE AIR-TO-AIR COMS TO ADVISE ANY ACFT THAT WE WERE DEVIATING; AND XMITTED RELEVANT INFO AS TO INTENT; ALT; DEV; AIRWAY AND INTXN INVOLVED. AIR CREW UTILIZED WX RADAR; TCAS AND VHF AIR-TO-AIR COMS FOR COORD AND TFC AVOIDANCE. NO OTHER AIR TFC WAS VISUALLY OBSERVED NOR INDICATED ON TCAS; AND NONE RESPONDED TO OUR XMISSIONS DURING THE DEV. WHILE REJOINING COURSE; ZMA RESPONDED TO OUR XMISSIONS DURING THE DEV. WHILE REJOINING COURSE ZMA WAS CONTACTED ABEAM ABC INTXN AND ADVISED OF THE DEV. THE MIA CTLR REQUESTED INFO AS TO THE DEV; WHICH THE CAPT PROVIDED. THE MIA CTLR VERIFIED THAT WE WERE NOW IN RADAR CONTACT AFTER REQUESTING IDENT. THE MIA CTLR WAS PROFESSIONAL AND HELPFUL IN PROVIDING GUIDANCE AFTER COMS AND RADAR CONTACT WERE ACHIEVED. THE FLT CONTINUED TO DEST WITHOUT FURTHER INCIDENT(S). THE NEWLY COMPRESSED AIRWAY STRUCTURE IN THE WATRS AREA AND RVSM ALT; COUPLED WITH LACK OF SUFFICIENT ENRTE COM ARE CONTRIBUTING FACTORS THAT WHEN COUPLED WITH REQUIRED NAV DEVS DUE TO HAZARDOUS WX; CREATE A POTENTIAL RISK TO ACFT SAFETY.