At about the time in question, there was in the DIKEB area (see map above) a SE-NW oriented pack of clouds, which in the moonlight from the low 7 o'clock position I would not identify as CB or squall line, more like a thick fog/haze area, but which showed up on wx radar as a thick (ylo/red) and continuous line about 20 NM thick and possibly extending to the TASIL area. At 370 or 380 we diverted 30 NM west of the airway, a bit shaky but not too bad. No lighting activity noted.
It was indeed difficult to switch from Atlantico to Dakar HF, in fact we had no contact until about 1:30 into their airspace.
Condolances to the crew and passenger's family.