SB PROP @ ARL $ARLP004
ARLP004 The ARRL Solar Report

ZCZC AP04
QST de W1AW
Propagation Forecast Bulletin 4 ARLP004

From ARRL Headquarters

Newington, CT January 23, 2026
To all radio amateurs

SB PROP ARL ARLP004
ARLP004 The ARRL Solar Report

Solar activity reached moderate levels with two M-class flares earlier this week.


The first flares occurred on January 21 in regions 4345 and 4349. Region 4345 continued to show development, as well as region 4342. Region 4341 was a main contributor to the C-level activity of the day, including a larger C-class flare on January 21. No Earth-directed CMEs were observed in the available coronagraph imagery.


Solar activity is likely to be at moderate (R1/R2, minor/moderate) levels,
with a slight chance for X-class flares (R3-strong) on January 24, primarily due to the magnetic potential of Regions 4341, 4342, and 4345.


Solar wind parameters reflected Coronal Mass Ejection (CME) influence transitioning into a high-speed stream paradigm, with the interplanetary magnetic field returned to largely enhanced background levels.

Solar wind speeds gradually decreased from about 800 km/s to 575 km/s at the end of the day.

Phi angle remained in the positive solar sector (away from the Sun),
indicating the coronal hole high-speed stream (CH HSS) dominant influence
over the period.

Solar wind parameters near Earth are expected to be dominated by the CH HSS conditions in the next three days.


Geomagnetic field activity is likely to reach (G1-Minor) geomagnetic storm levels on January 29 and unsettled to active levels on January 27 and 28,
then 30 and 31, and then from February 4 to 11. All enhancements in activity are due to the anticipated influence of multiple, recurrent Coronal Hole High Speed Streams. The remainder of the outlook period is expected to be mostly quiet.


Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, January 22, 2026, by F. K. Janda, OK1HH:


"A combination of favorable circumstances contributed to the northern lights
on the night of January 19-20, becoming one of the main stories in the media
in the following days.

In particular, much of Europe enjoyed very favorable weather conditions
thanks to an extensive high-pressure system, the center of which slowly moved southward from Russia across Ukraine, the Black Sea, and Turkey to the Middle East.

In its western part, a dry, cold wind blew from the south.
As a result, the aurora borealis was observed as far south as southern
Europe, for example in southern France, northern Italy, and Romania.

,
"Before the disturbance, a sunspot group, AR4341, had been gradually growing. Its magnetic configuration became increasingly complex, while to the west and south of it lay the extensive coronal hole No.

15. Then, in a position near the center of the solar disk, very favorable for the Earth to be hit by solar wind, a proton flare with the highest concentration and energy of protons in the last 36 years was observed. The beginning of the phenomenon was registered on January 18 at 1727 UT, with a maximum at 1809 UT and an end at 1851 UT.


"A very fast particle ejection (CME) began on January 18 at 1748 UT, lasted 5 hours, while was best observed around 1812 UT. The particle flow velocity was extreme, ranging from 2900 up to 3500 km/s. Therefore, the geomagnetic disturbance did not begin two to three days after the flare, as is usual, but the very next day - January 19. The aurora borealis was visible for most of
the night from January 19 to 20, and even at mid-latitudes it had not only
the usual red color, but also, exceptionally, green.


"The G4 geomagnetic disturbance lasted 15 hours and was followed by a G3 disturbance lasting 18 hours. The occurrence of numerous inhomogeneities in
the ionosphere caused large and variable attenuation. On the other hand, the values of the critical frequencies of the F2 ionospheric layer during the daytime in mid-latitudes on January 19 and 20 were above average. The
decline, typical for the end of the disruption, did not occur until January
21.


"Solar activity at the end of December indicated that the maximum of the eleven-year cycle is not yet over and will extend from 2024-2025 into part of 2026. During the rest of January, solar activity will decline only very
slowly, with a more significant decline occurring after the beginning of February, when another longer geomagnetic disturbance can be expected."


The Predicted Planetary A Index for January 24 to 30 is 5, 5, 5, 10, 15, 25, and 12, with a mean of 11. Predicted Planetary K Index is 2, 2, 2, 3,4, 5,
and 4, with a mean of 3.14. 10.7 centimeter flux is 180, 175, 170, 165, 160, 165, and 165, with a mean of 168.6.


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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