Message:19745 In: DX.ARL
From: NC8QDate: Sat, 28 Mar 26 16:09:00 Z
Newsgroups: DX.ARL
Subject: ARLP013 DX News
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R:260328/1611z @:N2NOV.#RICH.NY.USA.NOAM $:ARLP013
R:260328/1610z @:K7EK.#NOKY.KY.USA.NOAM $:ARLP013
R:260328/1609Z 72901@VE3CGR.#SCON.ON.CAN.NOAM LinBPQ6.0.25
R:260328/1609Z 48127@NC8Q.#DAY.OH.USA.NOAM LinBPQ6.0.25
ZCZC AP13
QST de W1AW
Propagation Forecast Bulletin 13 ARLP013
>From ARRL Headquarters
Newington, CT, March 27, 2026
To all radio amateurs
SB PROP ARL ARLP013
ARLP013 The ARRL Solar Report
Solar activity was at low levels with seven numbered active regions on the disk.
The largest event of the period was a C3.7 flare on March 25 from Region 4400. Region 4403, which was numbered last period, is
the suspected source of several flares observed beyond the limb before its rotation onto the disk. Due to its proximity to the
northeast limb, foreshortening continues to prevent a definitive characterization of its complexity and extent.
The remaining disk regions exhibited varying degrees of decay and evolution. Region 4397 has dissipated into a small unipolar g
roup, while Region 4398 underwent penumbral decay. Region 4399 remained largely stable, though it continues to fluctuate betwee
n a unipolar and bipolar state due to the short-lived trailing spots. Significant internal changes were noted in the more compl
ex groups: Region 4400 experienced extensive reconfiguration and flux emergence, and gained a gamma configuration. Similarly, R
egion 4401 exhibited persistent flux emergence and an expansion of penumbral area in its trailing spots. Region 4402 showed a d
ecline in its leader spot cluster.
No Earth-directed coronal mass ejections (CMEs) were observed in available coronagraph imagery. Solar activity is expected to b
e low with a chance for M-class (R1-R2/minor-moderate) flares through March 28.
For the first several hours of the reporting period, solar wind parameters reflected the continued waning influence of a negati
ve polarity coronal hole high-speed stream (-CH HSS). During this time, solar wind speed decreased from approximately 550 km/s
to 515 km/s.
On March 25, a transient CME began its passage through the near-Earth environment. Accompanied by a rise in solar wind speed to
a peak of 633 km/s. Solar wind parameters are expected to remain mildly enhanced as current influences diminish. Additional en
hancements are anticipated on March 26, following the arrival of another component of the March 22 CME. Following this passage,
a gradual return to a nominal, slow-speed regime is forecast through March 28.
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, March 26, 2026, by F. K. Janda, OK1HH:
Solar activity declined during the first half of March. Despite preliminary forecasts of a subsequent increase, it not only rem
ained low for another week, but observations also showed no signs of an impending rise. Eventually, however, solar activity did
begin to rise, while the power flux of solar radio noise at a wavelength of 10.7 cm (abbreviated as solar flux) rose to the le
vel seen in early February.
The increase in geomagnetic activity also came as a surprise. Although it initially recurred as expected after 27 days (i.e., M
arch 13ñ14), the next recurrence not only came later, but the disturbance lasted twice as long as expected, while it was parti
cularly intense on March 22 (reaching G3 instead of the anticipated G1ñG2). However, given the presence of large coronal holes
No. 31 and 33 in the center of the solar diskóthat is, facing Earthóthe intensity of the disturbance may not have been a sur
prise.
Similarly, regarding future developments, it can be assumed that the next geomagnetic disturbance will occur later, and the sam
e applies to the expected increase in solar activity; however, this will still be during the third decade of April, when we can
expect the first occurrences of the sporadic E layer in the mid-latitudes of the Earthís northern hemisphere. This, combined
with the expected increase in daily MUF values, should improve the DX signal propagation on the upper shortwave bands
The Predicted Planetary A Index for March 28 to April 3 is 5, 8, 15, 10, 5, 5, 18, with a mean of 9.4. The Predicted Planetary
K Index is 2, 3, 4, 3, 2, 2, 5 with a mean of 3. 10.7 centimeter flux is 130, 128, 125, 125, 130, 120, 120 with a mean of 125.4
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