A week after strong geomagnetic storms pushed the northern lights far beyond their usual range, fresh solar activity could make the aurora visible across much of the continental U.S. as forecasters place Earth under a ‘severe’ category geomagnetic storm watch.
NOAA Flags Strong Solar Flare, Issues Watch
Early Tuesday, NOAA's Space Weather Prediction Center (SWPC) reported a strong solar flare and issued a severe-level geomagnetic storm watch, cautioning that while "detrimental impacts to some of our critical infrastructure technology… mitigation is possible." It is worth noting that such warnings are routine in big storms and often pass with little public disruption.
The agency warns that storms may be strong enough to bring the aurora as far south as Alabama and California, depending on how Earth's magnetic field lines up during peak periods.
How Solar Flares Are Classified And Measured
As per SWPC’s definition, a flare is an “eruption of energy from the sun that generally lasts minutes to hours." The agency logged multiple events this week as the sun continues an active run, however, these flares are "generally not common, although not necessarily unusual."
According to classification by NASA, flares are graded by strength like earthquakes. B, C, M and X figures, with each letter a tenfold jump in energy and a 1–9 scale within each class, except X, which can exceed 9. The largest recorded in the space era is an estimated X45 from 2003.
On impacts, NASA notes B- and C-class flares are typically too weak to notice at Earth's surface. M-class can cause brief radio blackouts at the poles and minor radiation storms that might endanger astronauts, while X-class events can spark stronger radiation storms that affect satellites and even deliver small radiation doses to high-latitude airline passengers.
Severe Geomagnetic Storm Watch And Optimal Viewing Windows
SWPC has a Severe G4 geomagnetic storm watch in effect through Wednesday — the second-highest level on NOAA's five-step scale, capable of causing power-grid voltage control problems, GPS errors and radio issues, with conditions expected to ease to a G3 (strong) Thursday and G1 (minor) Friday. Best viewing windows according to the agency range from 4 p.m.–10 p.m. ET, then 10 p.m.–1 a.m. ET.
The SWPC forecasts the best aurora viewing odds for the northern states that include Alaska and Washington across the northern Plains and Upper Midwest to New England. Eric Snitil, chief meteorologist at Nexstar's WROC, tells The Hill that conditions may strengthen enough to push glimmers farther south into parts of Nevada, Utah, Colorado, Kansas, Missouri, Kentucky, West Virginia, Virginia, Maryland, and New Jersey.
Photo Courtesy: Mumemories on Shutterstock.com
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