Earth under the influence of positive polarity CH HSS, G2 – Moderate geomagnetic storm

Earth is under the influence of a positive polarity coronal hole high speed stream (CH HSS). This is causing G1 – Minor to G2 – Moderate geomagnetic storming.

Solar wind parameters were at background levels until about 06:00 UTC on October 24 when co-rotating interaction region (CIR) ahead of a positive polarity CH HSS, began interacting with Earth's magnetosphere, causing enhancements in the solar wind environment, SWPC forecasters said.

At 10:30 UTC on October 24, solar wind speeds increased to near 500 km/s, total field reached 14 nT, and the Bz component saw a maximum southward deflection to -12 nT. Phi remained mostly negative until just after 11:00 UTC, when it rotated into a mostly positive orientation.

Wind speeds eventually reached near and over 600 km/s as CH HSS effects increased toward the end of the UTC day and into October 25. 

Solar wind parameters are expected to remain enhanced on October 25 and to begin to taper off on October 26 and 27 as the CH HSS moves out of geoeffective position.

Geomagnetic K-Index of 6 (G2 – Moderate geomagnetic storm) threshold was reached at 08:49 UTC on October 25.

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Space Weather Message Code: ALTK06
Serial Number: 475
Issue Time: 2019 Oct 25 0850 UTC

ALERT: Geomagnetic K-index of 6
Threshold Reached: 2019 Oct 25 0849 UTC
Synoptic Period: 0600-0900 UTC
Active Warning: Yes
NOAA Scale: G2 – Moderate
www.swpc.noaa.gov/noaa-scales-explanation
Potential Impacts: Area of impact primarily poleward of 55 degrees Geomagnetic Latitude.
Induced Currents – Power grid fluctuations can occur. High-latitude power systems may experience voltage alarms.
Spacecraft – Satellite orientation irregularities may occur; increased drag on low Earth-orbit satellites is possible.
Radio – HF (high frequency) radio propagation can fade at higher latitudes.
Aurora – Aurora may be seen as low as New York to Wisconsin to Washington state.

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There are no active regions on the Earth side of the Sun for 22 consecutive days, as of October 25. We had a total of 221 spotless days since the start of the year (74 percent). We are in a deep solar minimum.

In all of the plots, the black line represents the monthly averaged data and the blue line represents a 13-month smoothed version of the monthly averaged data. For the Sunspot Number and F10.7cm, the forecast for the rest of the solar cycle is given by the red line.

Featured image credit: SOLEN