Region AR4246 underwent significant evolution, growing in overall
size while gaining multiple new spots. Subsequently, AR4246 was the
main provider of activity which included an M1.2 flare on October
13. Several coronal mass ejections (CMEs) with potential
Earth-directed components are in the mix at this time.

Additional modeling efforts are underway to perhaps confirm those
suspicions. The largest flare was a long-duration M4.8/2n on October
15. Modeling efforts showed the ejecta to be on a northward
trajectory and not on an Earthward course.
 
Other notable activity included a prominence eruption off the ENE
limb-first visible in LASCO C2 imagery on October 14. Given the
location of the event, initial analysis suggests this ejecta to be
well into foul-ball territory and not Earth-directed. Additional
modeling efforts are underway to perhaps confirm this suspicion.
 
Slight decay was observed in the intermediate portion of Region
AR4248 as it grew in length. Region AR4247 was in decay as well. The
remaining regions were unremarkable in comparison. No new regions
were assigned numbers this period. Minor to moderate (R1-R2) radio
blackouts are likely for the next 3 days, with a slight chance for
an isolated R3 (strong) event, due to the current and potential
flare activity of Regions AR4246 and AR4248.
 
Solar wind parameters continued to reflect the influence of a
negative polarity coronal hole high speed stream (CH HSS). Solar
wind speeds finally dipped below 600 km/s and phi was predominantly
in the negative solar sector.
 
Solar wind parameters are expected to continue at enhanced levels,
although gradually waning, and continuing through October 17, due to
CME arrivals from the October 11 to 13 timeframe originating from
AR4246.  Solar activity reached moderate levels due to M-class flare
activity.

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere, October 16, 2025, by F. K. Janda, OK1HH:

"In line with forecasts, solar activity continued to gradually
increase, including several moderately strong flares. These were
mostly observed in the active region NOAA 4246, located in the
northwest of the solar disk, while approaching its limb.

"The second of the two larger active regions is NOAA 4248, also
located in the northwest, but closer to the central meridian and the
solar equator, while relatively close to the extensive coronal hole
No. 87. In the coming days, AR NOAA 4248 will move into the active
longitudes. Therefore, its eruptive activity will increase. Between
it and the aforementioned coronal hole, a source of intensified
solar wind will form, which will hit Earth during the coming week.

"Even earlier, on October 16, when this text is being written, we
expect a G2 geomagnetic disturbance, which will first cause a brief
improvement and then a deterioration in ionospheric propagation of
short waves, which have been rather average so far. The exception
was a shorter increase in MUF on October 15 between 1000 and 1200
UTC, probably caused by an intensification of the solar wind.

"Solar activity should remain at current levels for the rest of the
month. Fluctuations in propagation conditions, mostly around average
with occasional deterioration, will depend on the irregular
occurrence of geomagnetic disturbances."
 
The latest video report from Dr. Tamitha Skov, WX6SWW, can be found
on YouTube at:  https://www.youtube.com/watch?v=pAZtua4DZUs .
 
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service web page at, http://arrl.org/propagation-of-rf-signals. For
an explanation of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere . Information and
tutorials on propagation can be found at, http://k9la.us/ .

Also, check this:

https://bit.ly/3Rc8Njt

"Understanding Solar Indices" from September 2002 QST.

The Predicted Planetary A Index for October 18 to 24 is 5, 5, 15,
10, 8, 5, and 5, with a mean of 7.6.  Predicted Planetary K Index is
2, 2, 5, 3, 3, 2, and 2, with a mean of 2.7.  10.7-centimeter flux
is 150, 150, 150, 150, 145, 140, and 145, with a mean of 147.1.