G1 – Minor Geomagnetic Storm Watch in effect for October 24 and 25


A recurrent, positive polarity coronal hole high speed stream (CH HSS) is anticipated to rotate into an Earth-connected position on October 24. As a result, a G1 – Minor Geomagnetic Storm Watch is in effect for Thursday and Friday, October 24 and 25, 2019.

A co-rotating interaction region (CIR) is expected to precede the CH HSS and is forecast to arrive mid to late UTC-day on October 24. Effects from CIR arrival, coupled with CH HSS onset, are likely to cause geomagnetic responses to G1 storm levels, SWPC forecasters said.

Elevated solar wind speed due to the CH HSS is forecast to continue into Friday, October 25, and likely result in an additional early period of G1 storm levels.

This CH HSS has been a persistent feature for a few rotations and has a history of causing geomagnetic storm conditions (August 31 – September 1, and again September 27 – 28).

Space Weather Message Code: WATA20
Serial Number: 865
Issue Time: 2019 Oct 22 2112 UTC

WATCH: Geomagnetic Storm Category G1 Predicted
Highest Storm Level Predicted by Day:
Oct 23: None (Below G1) Oct 24: G1 (Minor) Oct 25: G1 (Minor)
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.


Solar activity is at very low levels, with no Earth-directed CMEs observed in available satellite imagery, and is expected to persist at very low levels through October 25.

There were no sunspots observed on the Earth side of the Sun for the past 20 days. As of October 22, the Sun has been spotless for 219 days or 74% so far this year.

Featured image credit: NOAA/SWPC


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