The Sun Fired Off a Flare That Could Light Up US Skies This Week

Keypoints:

• • NOAA issued a G1 geomagnetic storm watch for August 27 and a G2 watch for August 28
  • The storms follow an M6.9 solar flare and multiple coronal mass ejections from sunspot region 4513
  • A coronal hole is also sending fast solar wind toward Earth, arriving around midday August 27
  • The Kp index could reach around 5.67 during the event
  • Auroras may become visible farther south than usual, potentially reaching states like Illinois and Oregon

A powerful M6.9 solar flare erupted from an active sunspot region on August 25. It sent coronal mass ejections streaming toward Earth and prompted NOAA's Space Weather Prediction Center to issue back-to-back geomagnetic storm watches. 

A minor G1 watch covers August 27, driven by fast solar wind escaping through a nearby coronal hole. A moderate G2 watch covers August 28, timed to when the coronal ejections themselves are expected to arrive.

These two events are expected to overlap and reinforce each other. Solar wind speeds could climb to around 600 kilometers per second as the coronal hole stream reaches Earth midday on August 27. Additional disturbance layers on top of that the following day, as the slower-moving coronal mass ejections finally catch up and collide with Earth's magnetic field.

NOAA estimates the Kp index, a standard measure of geomagnetic disturbance, could reach around 5.67 during the peak of this event. That sits well above the 0-to-2 range considered typical on a quiet day. A storm at this level can push the aurora oval unusually far south.

That shift matters for anyone hoping to catch a glimpse. Skywatchers in states that rarely see the northern lights, Illinois and Oregon among them, could get a rare shot at visible auroras if skies stay clear and timing lines up. 

Worth noting - the sunspot region responsible, numbered 4513, has continued producing additional M-class flares since the initial eruption, so forecasters are still watching closely for further activity before the week is out.