NOAA Forecasts Auroral Displays Across Northern US Following Solar Events

Aurora Borealis Forecast: Solar Storms to Light Up Skies Across Northern U.S.

A series of solar events, including coronal holes and coronal mass ejections (CMEs), have prompted NOAA's Space Weather Prediction Center to issue multiple forecasts for geomagnetic storms. These storms are expected to make the aurora borealis visible across the northern United States, with potential visibility extending into mid-latitude regions.

Cause of the Phenomena

The auroral displays are caused by the interaction of charged particles from the sun with Earth's magnetic field and atmosphere. Multiple solar events have been cited as the source of the incoming solar wind:

• Coronal Holes: Large openings in the sun's corona where magnetic fields open, allowing solar wind to escape as high-speed streams (HSS).
• Coronal Mass Ejections (CMEs): Large expulsions of plasma and magnetic field from the sun's outer atmosphere that travel toward Earth.
• Solar Flares: Intense bursts of radiation, including X-class flares, which can trigger CMEs.

According to NASA, auroras form when high-energy particles from the sun collide with atmospheric gases (such as oxygen and nitrogen) near Earth's magnetic poles, causing them to release light. The sun is currently in the maximum phase of its 11-year activity cycle (the solar maximum), which is characterized by an elevated frequency of solar eruptions and auroral displays.

Forecasted Geomagnetic Storm Classifications

NOAA's Space Weather Prediction Center uses a G-scale from 1 (minor) to 5 (extreme) to classify geomagnetic storms.

Forecasts have included the following conditions:

• Minor (G1) Conditions: Potential for minimal impact on power grids and satellite operations; aurora visibility typically limited to northern states.
• Moderate (G2) Conditions: Can cause minor to moderate radio blackouts and increase aurora visibility. Forecasts indicate these conditions are possible between 5:00 p.m. EDT and 2:00 a.m. EDT on April 17-18, as well as between 2:00 a.m. EDT and 5:00 a.m. EDT on April 18.
• Strong (G3) Conditions: Could make the aurora visible as far south as Illinois and Oregon. The U.K. Met Office noted a chance of strong geomagnetic bursts.
• Severe (G4) Conditions: The second-highest classification. G4 levels were confirmed at 2:38 p.m. EST on January 19, with conditions projected to continue through the evening and into January 20.
• S4 Solar Radiation Storm: A powerful solar radiation storm was reported as the largest observed in over 20 years, with the last S4 event occurring in October 2003.

Projected Aurora Visibility

Visibility predictions are based on the strength of the geomagnetic storm and local viewing conditions. Forecasts suggest the aurora may become visible across the northern third of the United States, with potential expansion further south under stronger storm conditions.

States with Potential Visibility

The following states have been cited across multiple forecasts as having a likelihood of seeing the aurora:

Less Common Potential Visibility

Under stronger storm conditions (G3 or above), the aurora has been reported as visible or forecasted to be visible further south, including in Alabama, California, Florida, New Mexico, Oklahoma, Tennessee, and Texas.

Scientific Context (Russell-McPherron Effect)

NOAA and other sources indicate that March and the period around the spring and fall equinoxes are often associated with increased geomagnetic activity. This phenomenon, known as the Russell-McPherron effect, occurs when Earth's magnetic field aligns with the magnetic field carried by the solar wind. This alignment can create temporary openings in Earth's magnetic field, facilitating the flow of solar wind toward the poles and enhancing aurora production.

Observational Guidance

Optimal Timing

• Viewing is generally recommended between 10 p.m. and 2 a.m. local time, or just after sunset and just before sunrise.
• Specific forecasts indicated favorable conditions between 1 a.m. and 7 a.m. EST on January 16-17, and between 1 a.m. and 4 a.m. EST on January 20 for G4-level activity.

Factors Influencing Visibility

• Location: Dark skies away from city lights with an unobstructed view of the northern horizon are recommended.
• Weather: Local cloud cover can obstruct the view.
• New Moon: A new moon provides darker skies, potentially enhancing viewing conditions.
• Magnetic Field Orientation: The CME's magnetic field (Bz component) must be aligned southward to effectively interact with Earth's magnetic field.

Tools and Technology

• NOAA Dashboard: NOAA's Space Weather Prediction Center website provides real-time aurora maps and forecasts.
• Smartphone Cameras: Phone cameras, particularly in night mode, can often detect fainter auroral glows not immediately visible to the naked eye.
• Applications: Apps like "My Aurora Forecast & Alerts" and the citizen science platform "Aurorasaurus" can provide localized forecasts and user-reported sightings.
• Photography: Mirrorless or DSLR cameras, or smartphones with night mode or manual exposure settings, may be used to capture aurora displays.

Broader Impacts of Geomagnetic Activity

According to NOAA, widespread technology impacts for the general public are not anticipated during these events.

Awareness of geomagnetic conditions is relevant for several technologies. Potential impacts include:

• Radio Communication: Minor to moderate radio blackouts affecting HF radio.
• Satellite Navigation: Potential interference with GPS satellite navigation and satellite-based communications.
• Power Grids: Ground-induced currents that can affect electric power transmission.
• Aviation: Potential impacts on space launch operations and air traffic control radio systems.
• Space Operations: Increased radiation exposure risk for astronauts, which can be mitigated by moving to shielded areas.

Agencies including NASA, the Federal Aviation Administration, and the North American Electric Reliability Corporation have been notified for preparatory purposes.