Negative polarity CH HSS sparks G1 geomagnetic storm

Earth is under the influence of a recurrent, polar-connected coronal hole which has sparked G1 (Minor) geomagnetic storming today. Unsettled to active conditions, with G1 storming likely, are expected to continue through March 2.

Geomagnetic K-index of 5 (G1 – Minor geomagnetic storming) threshold was reached at 10:36 UTC on March 1, 2017. Area of impact is primarily of 60 degrees Geomagnetic Latitude.

Under G1 conditions, weak power grid fluctuations can occur, minor impact is possible on satellite operations and aurora may be visible at high latitudes.

SWPC forecasters said unsettled to active conditions are expected, with G1 (minor) geomagnetic storming likely, on March 1 and 2 as a negative polarity, coronal hole high speed stream (CH HSS) becomes geoffective. Mainly unsettled to active levels are anticipated on March 3 as the CH HSS begins to subside.

Solar wind speeds ranging from 600 – 700 km/s are anticipated based on earlier observations from STEREO-A.

SWPC Alerts

Space Weather Message Code: ALTK05
Serial Number: 1063
Issue Time: 2017 Mar 01 1036 UTC

ALERT: Geomagnetic K-index of 5
Threshold Reached: 2017 Mar 01 1036 UTC
Synoptic Period: 0900-1200 UTC

Active Warning: Yes
NOAA Scale: G1 – Minor

NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/noaa-scales-explanation

Potential Impacts: Area of impact primarily poleward of 60 degrees Geomagnetic Latitude.
Induced Currents – Weak power grid fluctuations can occur.
Spacecraft – Minor impact on satellite operations possible.
Aurora – Aurora may be visible at high latitudes, i.e., northern tier of the U.S. such as northern Michigan and Maine.

Featured image: Geoeffective coronal hole on February 28, 2017. Credit: NASA/SDO/AIA, LMSAL