Upgraded ‘Severe’ Northern Lights Alert For 25 States Thursday

The weather forecast for this week's northern lights display has been upgraded, with NOAA's Space Weather Prediction Center warning of strong to severe geomagnetic storms that could develop on Thursday, June 4, and continue into Friday, June 5.

Skywatchers in northern U.S. states are advised to get outside and look north if skies are clear as it gets dark across North America. The forecast predicts an 82%-lit waning gibbous moon will rise in the east after midnight and brighten the night sky, potentially interfering with faint aurora.

Earlier forecasts suggested the strongest aurora activity would occur primarily on Friday, but NOAA's latest space weather outlook indicates that G2 (Moderate) and G3 (Strong) geomagnetic storms are likely in North America on Thursday afternoon and evening. The forecasters added that "there is a chance for isolated periods of G4 (Severe) geomagnetic storming during the peak of the multi-CME passage over 04-05 June."

NOAA's latest three-day forecast predicts Kp values reaching 6.33 (G2) between 15:00 and 18:00 UTC on June 4, rising to 6.67 (G3) between 18:00 and 21:00 UTC. Those periods correspond to the afternoon and evening across North America, potentially setting the stage for a widespread aurora display after dark.

The upgraded forecast follows the detection of multiple Earth-directed CMEs launched from the sun on June 3 and June 4. When multiple CMEs travel through space in close succession, they can interact and intensify one another, a phenomenon sometimes referred to as a "cannibal CME."

Experts note that aurora activity is often more predictable when forecasts are reliable. According to SpaceWeather.com, during similar storms in the past, naked-eye auroras have been visible in over 25 U.S. states.

To maximize viewing opportunities, observers should continue monitoring real-time space weather updates and check aurora webcams around the world as darkness falls. In addition, aurora watchers frequently use the Kp index to predict the intensity of a geomagnetic storm, but for aurora displays, the crucial factor will be the orientation of the interplanetary magnetic field embedded within the solar wind.

As the weather forecast improves, northern U.S. states and much of Canada can expect a more spectacular display of the northern lights. However, it's essential to note that the exact intensity of the display will depend on the orientation of the solar wind's magnetic field as the CME complex arrives.