Message:24159 In: PROP.ARL
From: NC8QDate: Sat, 13 Jun 26 15:49:00 Z
Newsgroups: PROP.ARL
Subject: ARLP024 Propagation Forecast
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ZCZC AP24
QST de W1AW
Propagation Forecast Bulletin 24 ARLP024
>From ARRL Headquarters
Newington, CT June 12, 2026
To all radio amateurs
SB PROP ARL ARLP024
ARLP024 The ARRL Solar Report
Solar activity has been at low levels this past week, with most of the C-level activity originating from Region 4465, including
the largest flare of the week, a C2.6 observed on June 10. There are currently 7 numbered sunspot regions on the disk, with Re
gion 4467 decaying to plage.
There was a Type-II radio sweep detected by the Radio Solar Telescope Network (RSTN) on June 10. That radio emission was associ
ated with a coronal mass ejection (CME) first observed at the NE quadrant by ground-based coronagraph imagery from HAO/MLSO cor
onagraph late June 10, and later by space-based coronagraph LASCO/C2. Modeling indicates there is no Earth-directed component.
Other CME activity was observed in the coronagraph imagery later in the period, but preliminary analysis indicated no Earth-dir
ected component.
Solar activity is expected to remain at low levels, with a chance for M-class flares and a slight chance for X-class flares.
NOAAís SOLAR-1 satellite became operational early on June 11, becoming the Space Weather Prediction Centerís primary source o
f solar wind data. Solar wind speeds continued to decrease after the passage of a weak transient, reaching 374 km/s at the end
of the period. Background solar wind conditions are expected through midday June 11, when a coronal hole high-speed stream (CH
HSS) is anticipated to become geoeffective through June 13.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, June 11, 2026, by F. K. Janda, OK1HH:
Overall solar activity is rather low and is expected to continue and decline through mid-June. Most active regions are relative
ly small, typically with a simple magnetic configuration. Nevertheless, class C flares are occasionally observed, sometimes acc
ompanied by CMEs.
Currently, CMEs from June 9 and 11 are expected to arrive, leading to an increase in geomagnetic activity from June 12 to 14. A
period of several days of calm activity is predicted to begin on June 16.
Shortwave propagation has begun to be significantly affected by the sporadic E layer, while its increased activity can be expec
ted to continue over the next few days.
The Predicted Planetary A Index for June 13 to June 19 is 6, 6, 8, 8, 5, 5, and 5 with a mean of 6.1. The Predicted Planetary K
Index is 2, 2, 3, 3, 2, 2, and 2 with a mean of 2.3. 10.7 centimeter flux is 128, 120, 118, 120, 122, 122, and 125 with a mean
of 122.1.
For more information concerning shortwave radio propagation, see www.arrl.org/propagation and the ARRL Technical Information Se
rvice web page at www.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. Information and tutorials on propagation can be found at http://k9la.us.
Also, check this: "Understanding Solar Indices" from September 2002 QST. https://bit.ly/3Rc8Njt
NNNN
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