SB PROP @ ARL $ARLP007
ARLP007 The ARRL Solar Report

ZCZC AP07
QST de W1AW
Propagation Forecast Bulletin 7 ARLP007

From ARRL Headquarters

Newington CT February 28, 2025
To all radio amateurs

SB PROP ARL ARLP007
ARLP007 The ARRL Solar Report

A Coronal Mass Ejection (CME) associated with a filament eruption became visible on February 26 at 1448 UTC. Model analysis determined this CME to be
a miss ahead of the Sun/Earth line.


Unsettled to active levels are likely on February 28 to March 1 as a Coronal Hole influence continues, and a glancing blow is possible from a Coronal Mass Ejection that occurred on February 25.


Solar activity is forecast to range from low to moderate levels through March 22.


Minor to Moderate activity (R1 to R2) is possible at different points throughout the period as active regions grow, evolve, and return from the far-side of the Sun. There is a slight chance for R3 (Major) or greater
events if any of the active regions develop additional complex magnetic structures.


Geomagnetic field activity is expected to be at quiet to unsettled levels
until March 6 with periodic, weak Coronal Hole influences. Unsettled to
active levels, with isolated G1 (Minor) storming conditions are likely from March 7 to 18 as recurrent negative polarity Coronal Holes are expected to be in a geoeffective position.


NOAA Space Weather forecasts a 55% chance of a Class-M flare, and a 10%
chance of a Class-X flare, both within the next 48 hours (February 28 to
March 1).


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


"Solar activity is now increasing, but the increase is irregular, which
causes, among other things, a decrease in the reliability of forecasts. Geomagnetically quiet periods, especially when associated with an increase in total solar activity (such as 20-23 February), are accompanied by improved conditions for ionospheric radio wave propagation. A subsequent disturbance
can cause even further improvement (which happened on 24 February).


"Following the increase in solar flare activity (from 23 February), two
proton flares were observed on 24 February. In the following days, the
Earth's ionosphere was under the influence of a solar-derived proton rain, after which the density of free electrons in it decreased due to
recombination.


"However, the worsening of conditions was only noticeable on 25 February. The very next day, 26 February, there was an improvement, in particular an
increase in the MUF on a global scale. The jump in the solar wind speed also contributed. However, the changes were so rapid, even within a single day,
that our assessment of the level of conditions could have been reversed, depending on the time of day and the frequency bands used.


"The developments described can be considered as a harbinger of a March increase in solar activity. Since the Spring Equinox is approaching, it will contribute to an improvement in ionospheric shortwave propagation, more accurately called decameter waves. The possible shorter worse spells on March 1-2 and March 5-6 will make no difference, with the seasonal improvement not fully manifesting itself until the second half of the month."


This weekend is the ARRL International DX SSB contest. Information can be
found at: www.arrl.org/arrl-dx [ https://www.arrl.org/arrl-dx?utm_source=Informz&utm_medium=Email&utm_campaign=ARRL
] .


For more information concerning shortwave radio propagation, see www.arrl.org/propagation [ http://www.arrl.org/propagation?utm_source=Informz&utm_medium=Email&utm_campaign=ARRL
] and the ARRL Technical Information Service web page at, www.arrl.org/propagation-of-rf-signals [ http://arrl.org/propagation-of-rf-signals ] . For an explanation of numbers used in this bulletin, see www.arrl.org/the-sun-the-earth-the-ionosphere [ http://arrl.org/the-sun-the-earth-the-ionosphere ] . Information and
tutorials on propagation can be found at, http://k9la.us [ http://k9la.us/ ]
..


Also, check this:
https://bit.ly/3Rc8Njt [ https://bit.ly/3Rc8Njt ] - "Understanding Solar Indices" from September 2002 QST.


The predicted 10.7 cm flux for February 28 to March 6 is 195, 195, 190, 190, 190, 190, and 185, with a mean of 190.7. The predicted Planetary A Index for February 28 to March 6 is 12, 10, 8, 5, 5, 5, and 5, with a mean of 7.1. The predicted K Index for February 28 to March 6 is 4, 3, 3, 2, 2, 2, and 2, with
a mean of 2.6.

NNNN
/EX

ARRL The National Association for Amateur Radio(R)
Unsubscribe [ https://www.arrl.org/opt-in-out?utm_source=Informz&utm_medium=Email&utm_campaign=ARRL
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SB PROP @ ARL $ARLP007
ARLP007 The ARRL Solar Report

ZCZC AP07
QST de W1AW
Propagation Forecast Bulletin 7 ARLP007

From ARRL Headquarters

Newington, CT February 13, 2026
To all radio amateurs

SB PROP ARL ARLP007
ARLP007 The ARRL Solar Report

Solar activity reached moderate levels early this week. The strongest event
was an M1.4 flare observed on February 11 in Region 4366. This region also produced nine C-class flares.


Region 4373 produced a C1.8/Sf flare on February 11. This region displayed
some minor area growth. Regions 4369 and 4371 exhibited some minor decay. The other spotted regions remained unchanged. New Region 4375 was numbered. A
small loop structure near S22W80 erupted around February 10.


Around the same time, a large filament (located near N15W25) lifted off and disappeared from GONG H-alpha imagery. Between faint features in disk imagery and a data gap in STEREO coronagraph imagery, it is difficult to determine whether the filament is superimposed over the earlier eruption or largely
fell back down to the Sun.

Analysis of the coronagraph structure indicates there is no Earth-directed component. However, there is the potential for interaction between the
eruption and the co-rotating interaction region (CIR) ahead of an anticipated high-speed stream, which may cause the CIR to become compressed and arrive later than under ambient conditions.


Solar activity is expected to be at low levels through February 14.
Probability for M-class (R1-R2) flares dropped to a slight chance on February 14, with a slight chance for X-class (R3 or greater) flares on February 12 as Region 4366 continues to rotate behind the western limb.


Solar wind parameters continued to reflect waning influence of a negative polarity coronal hole high-speed stream (CH HSS) with discrete mild disturbances likely associated with embedded transient structures. Solar wind speeds remained generally elevated, slowly decreasing from approximately 500 km/s to 400 km/s by the end of the reporting period.


On February 14, the wind environment is expected to become more enhanced late in the day due to CIR effects from a large positive polarity coronal hole high-speed stream (CH HSS) coupled with possible weak CME effects from the February 11 eruption.


Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, February 12, 2026, by F. K. Janda, OK1HH:


"The last largest sunspot group, also known as NOAA active region 4366, which suddenly appeared in the southeast of the solar disk on January 30, has now disappeared. Until then, it was the source of a long series of energetically significant flares. (This group could reappear on the eastern limb of the
solar disk around February 23.) Overall solar activity declined, slowly at first, and more significantly after the setting of AR 4366.


"The geomagnetic field was mostly quiet to unsettled, with the exception of a disturbance on February 5 and calm days on February 8-9. Due to the absence
of major and longer geomagnetic disturbances and despite the decline in solar radiation, ionospheric propagation conditions for short waves were mostly slightly above average.


"A slight increase in solar activity can be expected from mid-February, meanwhile it appears that geomagnetic activity could also increase slightly
at around the same time. Until then, ionospheric propagation conditions for short waves are likely to remain slightly above average.


"It is not yet possible to predict whether the minor disturbances from
January 16 to 17 and, in particular, the more significant disturbances around January 20 will recur (in the latter case, this would be around February 16, when geomagnetic activity is likely to increase, but probably only to an 'active' level)."


The latest solar report from Dr. Tamitha Skov, WX6SWW, can be found on
YouTube at https://youtu.be/BECqZ6z1yi0?si=YXv2-V23040HzMQA [ https://youtu.be/BECqZ6z1yi0?si=YXv2-V23040HzMQA ] .


Predicted Planetary A Index for February 14 to 20 is 5, 5, 15, 15, 15, 15,
and 15, with a mean of 12.1. Predicated Planetary K Index is 2, 2, 4, 4, 4,
4, and 4, with a mean of 3.4. 10.7-centimeter flux is 140, 150, 160, 170,
180, 175, and 170, with a mean of 163.6.


For more information concerning shortwave radio propagation, see www.arrl.org/propagation [ http://www.arrl.org/propagation?utm_source=Informz&utm_medium=Email&utm_campaign=ARRL
] and the ARRL Technical Information Service web page at www.arrl.org/propagation-of-rf-signals [ http://arrl.org/propagation-of-rf-signals ] . For an explanation of numbers used in this bulletin, see www.arrl.org/the-sun-the-earth-the-ionosphere [ http://arrl.org/the-sun-the-earth-the-ionosphere ] . Information and
tutorials on propagation can be found at http://k9la.us [ http://k9la.us/ ] .


Also, check this: "Understanding Solar Indices" from September 2002 QST. https://bit.ly/3Rc8Njt [ https://bit.ly/3Rc8Njt ]

NNNN
/EX

ARRL The National Association for Amateur Radio(R)


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