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Solar activity has been at low levels with only minor C class
flaring through April 24, 2025, and is expected to be moderate with
a chance of M class flares, R1 to R2, Minor to Moderate, through
April 26.  No Earth directed Coronal Mass Ejections, or CMEs, have
been observed.  A southwest CME was observed on April 23 and is
considered to be far side due to the lack of any on disk plasma
motion/flare activity.  Solar wind parameters continued to be
slightly enhanced due to the Coronal Hole High Speed Streams, or CH
HSS, associated with the positive polarity coronal holes in the
southern hemisphere.  Solar wind parameters are expected to continue
to be influenced by positive polarity, with CH HSS conditions
through April 26.  Nominal conditions are expected thereafter.  On
April 25, Spaceweather.com reported the Earth was struck by an
interplanetary shockwave on April 24 around 0700 UTC. An
interplanetary shock wave is an abrupt change in the solar wind,
probably caused by the Coronal Mass Ejection.  Overall, solar
activity remained at low levels.  Region AR4064 remained the largest
sunspot group on the disk.  The regions intermediate spots grew in
penumbral area over the past 24 hours.  The geomagnetic field is
expected to remain at mostly quiet to unsettled levels, with active
conditions likely on April 27 due to the influence from multiple
positive polarity CH HSS.  There are currently 11 numbered sunspot
regions on the solar disk.  Solar activity is expected to be low
with a chance for M class flares on April 26 and 27.  Links to
articles or other websites mentioned in this bulletin can be found
in teleprinter, packet, and Internet versions of 2025 Propagation
Forecast Bulletin ARLP015.  The Predicted Planetary A Index for
April 26 to May 2 is 8, 8, 6, 6, 6, 25, and 35, with a mean of 13.4.
The Predicted Planetary K Index is 3, 3, 2, 2, 2, 5, and 6, with a
mean of 3.3.  Predicted 10.7 centimeter flux is 165, 165, 170, 170,
170, 170, and 175, with a mean of 169.3.

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