UPDATED STORM FORECAST: NOAA forecasters have upgraded their geomagnetic storm watch from category G2 (moderate) to category G3 (strong) in response to models suggesting multiple CME impacts on Aug. 18-19. During such storms naked-eye auroras can descend into the USA as far south as Illinois and Oregon (geomagnetic latitude 50 degrees). Although the storm could become "strong", power grids and satellites are in no danger. Extreme storms are required for that.
SOLAR ACTIVITY IS HIGH: Active sunspot AR3078 has been flaring almost constantly since it developed a delta-class magnetic field early yesterday.The strongest flare so far, an M5-category explosion on August 16th (0758UT), produced a shortwave radio blackout over the Indian Ocean (map).
A series of coronal mass ejections (CME) associated with these flares could begin grazing Earth's magnetic field during the late hours of Aug. 18th adding their effect to the possible "Cannibal CME event" described below
POTENTIAL 'CANNIBAL CME' EVENT (UPDATED): On Aug. 14th, a dark plasma eruption hurled one CME toward Earth. On Aug. 15th, an exploding magnetic filament launched another CME right behind it. The two CMEs will arrive together on Aug.18th, according to the latest forecast model from NOAA
This could be a "Cannibal CME" event. In other words, the second CME might overtake and gobble up the first, creating a mish-mash of the two. Cannibal CMEs contain tangled magnetic fields and compressed plasmas that sometimes spark strong geomagnetic storms.
