On Wednesday, March 26, around 2130 UTC a Major Storm occurred.  At
one point, the Planetary A Index was 49, and the Planetary K Index
was at 6.

Solar wind parameters are expected to remain enhanced due to
continued coronal hole high-speed stream influences with waning
effects likely by March 29.

The Solar Radiation Storm Forecast for March 29 and 30 has a 1
percent chance of a S1 or greater storm.

No S1 (Minor) or greater solar radiation storms are expected.  No
significant active region activity favorable for radiation storm
production is forecast.

The Radio Blackout forecast calls for a chance for isolated R1-R2
(Minor-Moderate) radio blackouts due to M-class flare activity will
persist through March 30 primarily due to the potential exhibited by
AR4043.

From Space Weather Prediction Center: "Since February 25, 2025, the
Space Weather Prediction Center (SWPC) has presented new coronagraph images and data from the GOES-19 Compact Coronagraph-1 (CCOR-1). The images and data are updated every 15 minutes.

"Imagery from the Compact Coronagraph (CCOR) instruments is used by
the SWPC Forecast Office to characterize activity in the outermost
part of the Sun's atmosphere known as the corona. This includes
monitoring data for transient events like coronal mass ejections
(CMEs), as well as monitoring the impacts the corona has on the
steady stream of plasma, referred to as the solar wind, emanating
from the Sun. Ultimately, information derived from CCOR images will
be used as inputs to the WSA-Enlil model to forecast the impacts of
CMEs and the solar wind on Earth.

"Note: Until such time as GOES-19 becomes operational, currently
planned for April 4th, the animations and data are to be considered
'preliminary and non-operational.' In particular, CCOR-1 data will
not update between 3/21 and 4/1 due to the spacecraft drifting to
its operational location."

Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere - March 27, 2025, by F. K. Janda, OK1HH:

"Most forecasts, including those from NOAA, have been consistent
over the past week that a strong G3-class geomagnetic storm would
develop on Sunday, March 23. In fact, a CME was expected to directly
impact the Earth. Although the source of the CME was only the
M1-class solar flare from AR4028, even weaker CMEs can produce
strong geomagnetic disturbances, especially on days around the
equinoxes. In the end, however, paradoxically, 23 March was the
relatively quietest day.

"However, a large coronal hole caught our attention this week, while
we expected that once it reached the central meridian region, the
solar wind stream would head directly towards Earth. This is what
happened and in the following days, especially on March 26, a G2
class geomagnetic storm developed. The solar wind speed increased
from 400 km/s to 700 km/s. On March 27, the increase continued to
over 800 km/s (1.8 million mph).

"Shortwave propagation conditions were particularly degraded along
paths through the higher latitudes of the Northern Hemisphere.
Outside of these, there was also a more pronounced decrease in MUF
on routes that crossed South America and the South Atlantic where
geomagnetic anomalies are located.

"While late March and early April are periods with traditionally
better-than-average shortwave propagation conditions, this time our
expectations will only be partially met. Solar activity is lower
than would be consistent with the current phase of the solar cycle -
and disturbances are relatively common."

A partial Solar Eclipse occurs on March 29, 2025. Details can be
found at,
https://science.nasa.gov/eclipses/future-eclipses/mar-29-2025-eclipse/
.

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 10.7 centimeter flux for March 29 to April 3 is 160,
165, 165, 170, 170, and 175, with a mean of 167.5.  The predicted
Planetary A Index is 8, 5, 5, 5, 5, and 10, with a mean of 6.3.  The
predicted Planetary K Index is 3, 2, 2, 2, 2, and 3, with a mean of
2.3.