NOAA Forecasts 70 Percent Chance of M-Class Solar Flares
Solar Activity remains high, as participants in the CQ World Wide DX Contest (phone) experience openings on the higher bands. NOAA forecasters are estimating a 70 percent chance of M-flares and a 35 percent chance of X-flares during the next 24 hours. According to NOAA, M-class flares can cause brief radio blackouts affecting Earth’s polar regions, while X-class flares are major events that can trigger planet-wide radio blackouts and long-lasting radiation storms.
NOAA says that over the next three days — October 26-28 — a series of coronal mass ejections (CMEs) created by recent eruptions on the sun “will deliver glancing blows to Earth's magnetic field, possibly sparking polar geomagnetic storms.” An X1-flare on October 25 was, NOAA says, “remarkable not only for its strength, but also for its interconnectedness. The flare was bracketed by two erupting magnetic filaments, each located hundreds of thousands of kilometers from the instigating sunspot AR1882. The whole episode was reminiscent of the famous global eruption of August 2010.” And, NOAA goes on to say, it happened again today.
NOAA explains that these flares and eruptions “are likely connected by magnetic fields, which thread through the whole broad region. Like dominoes falling, one explosion triggers another as shock waves follow magnetic fields from blast site to blast site.”
The SOHO satellite observed a CME emerging from the blast site, NOAA says, but it is too soon to say whether it is heading for Earth.
Electromagnetic radiation from the October 25 X2-class solar flare significantly affected Earth’s upper atmosphere. “As a wave of ionization swept across the dayside of the planet, the normal propagation of shortwave radio signals was scrambled,” NOAA reports. “During the time that terrestrial shortwave transmissions were blacked out, the sun filled in the gap with a loud radio burst of its own. Solar radio bursts are caused by strong shock waves moving through the sun's atmosphere. (Electrons accelerated by the shock front excite plasma instabilities which, in turn, produce shortwave static.) They are usually a sign that a CME is emerging from the blast site--and indeed this flare produced a very bright CME.”
NOAA’s Space Weather Prediction Center (SWPC) says R1 (minor) solar flare radio blackout activity continued with only G1 (minor) geomagnetic storm conditions are predicted for October 28.