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NOAA issues an extended warning: Geomagnetic K-index of 4 expected - October 11, 2021

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  • NOAA issues an extended warning: Geomagnetic K-index of 4 expected - October 11, 2021
    GEOMAGNETIC STORM WARNING: NOAA forecasters have modeled the trajectory of yesterday's CME and confirmed that it will likely arrive on Oct. 11th. The impact could spark G1 to G2-class geomagnetic storms. If a moderately-strong G2-storm materializes, sky watchers in the United States could see auroras as far south as a line connecting New York to Oregon. Aurora alerts: SMS Text.
    A 'HALO CME' IS COMING: This could be the first head-on CME strike of young Solar Cycle 25. Yesterday, Oct. 9th, an M1.6-class solar flare in the magnetic canopy of sunspot SR2882 hurled a coronal mass ejection (CME) toward Earth. SOHO coronagraphs recorded the storm cloud coming almost straight toward us:
    This is called a 'halo CME' because CMEs heading directly for Earth seem to form a 360-degree halo around the sun. CMEs heading directly away from Earth can form a halo, too, but that's another story.

    So far this year, dozens of CMEs have missed Earth. Many of them were near misses, provoking no more than minor geomagnetic unrest as they passed by. This time, however, the sun is shooting straight...

    Ask Congress to Investigate COVID Origins and Government Response to Pandemic H.R. 834

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  • #2

    Space Weather Message Code: WARK04 Serial Number: 3943 Issue Time: 2021 Oct 11 0239 UTC

    EXTENDED WARNING: Geomagnetic K-index of 4 expected Extension to Serial Number: 3942 Valid From: 2021 Oct 10 2220 UTC Now Valid Until: 2021 Oct 11 1200 UTC Warning Condition: Persistence

    NOAA Space Weather Scale descriptions can be found at

    Potential Impacts: Area of impact primarily poleward of 65 degrees Geomagnetic Latitude. Induced Currents - Weak power grid fluctuations can occur. Aurora - Aurora may be visible at high latitudes such as Canada and Alaska.