• The ARRL Solar Update

    From ARRL de WD1CKS@VERT/WLARB to QST on Fri May 8 21:43:00 2026
    05/08/2026

    Solar activity was at low levels this past week with occasional
    B-class and isolated low-level C-class flares. The largest event of
    the period was a C1.4/Sf flare from Region 4429 on May 5.

    There are currently six numbered regions on the visible disk as 4434
    decayed to plage and Region 4428 rotated beyond the western limb as
    an E-type group. The remaining regions mostly showed signs of decay.
    Region 4425 appeared stable, though full characterization is
    difficult due to extreme limb proximity. Region 4429 showed continued submergence and decay, decreasing in both area and length along with
    a total loss of penumbra.

    Region 4431 showed some minor new development, with a few small spots
    emerging in both polarities following recent decay. Region 4432 had
    minor emergence in its intermediate spots, despite an overall gradual
    decrease in extent. The remaining regions were mostly stable.

    No Earth-directed CMEs were observed in available coronagraph

    Flare probabilities increase beginning May 8 as up to two active
    regions rotate into view from beyond the eastern limb.
    Considering the size of these regions and recent far-side eruptions
    seen in coronagraph imagery, solar activity is expected to increase
    May 8 - 9 with a chance for M-class (R1-R2/minor-moderate) flares and
    a slight chance for X-class (R3/strong or greater) flares.

    Solar wind parameters returned to near background levels as transient
    coronal mass ejection (CME) influences waned. Solar wind speeds
    averaged around 375 km/s. The phi angle was predominantly in a
    positive (away) orientation for the majority of the period with a few short-lived oscillations into a negative (toward) orientation during
    the period.

    Spaceweather.com[1] reports a big and active sunspot hiding behind the
    sun's northeastern limb is about to reveal itself, rotating into view
    this weekend. A dramatic M2-class solar flare on May 7th confirmed
    its approach. The unnamed sunspot has produced at least 5 CMEs in
    recent days. If this production continues, Earth could soon be in
    line for a solar storm.

    Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
    Ionosphere,ÿ May 7, 2026, by F. K. Janda, OK1HH:

    Overall solar activity declined slowly but steadily in late April and
    early May. Eruptive activity was low, with active regions mostly and
    featuring a simple magnetic field configuration. Geomagnetic activity
    increased significantly only on May 4, after which the polarity of
    the longitudinal component of the interplanetary magnetic field
    returned to positive values. The ionosphere returned to a state
    favorable for shortwave propagation since May 6.

    Solar activity is likely to remain at current levels, while should
    decline shortly and slightly in mid-May. Geomagnetically quiet days
    can be expected starting May 10 again. Prior to that, there will be a
    slight increase in activity, likely on May 8. No other significant
    fluctuations are likely.

    The latest solar report from Dr. Tamitha Skov, WX6SWW, can be found
    on YouTube. https://www.youtube.com/watch?v=lNcaoB7be-k[2]

    The Predicted Planetary A Index for May 9 to May 15 is 10, 6, 5, 5,
    5, 5, and 25 with a mean of 8.7. The Predicted Planetary K Index is
    3, 2, 2, 2, 2, 2, and 5 with a mean of 2.6. 10.7 centimeter flux is
    130, 130, 125, 125, 120, 115, and 120 with a mean of 123.6.
    ÿ

    For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[3]ÿand the ARRL Technical Information
    Service web page at,ÿhttp://arrl.org/propagation-of-rf-signals[4]. For
    an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[5]ÿ. Information and
    tutorials on propagation can be found at,ÿhttp://k9la.us/[6]ÿ.

    Also, check this:

    https://bit.ly/3Rc8Njt[7]

    "Understanding Solar Indices" from September 2002ÿQST.


    [1] http://Spaceweather.com
    [2] https://www.youtube.com/watch?v=lNcaoB7be-k
    [3] http://www.arrl.org/propagation
    [4] http://arrl.org/propagation-of-rf-signals
    [5] http://arrl.org/the-sun-the-earth-the-ionosphere
    [6] http://k9la.us/
    [7] https://bit.ly/3Rc8Njt
    ---
    þ Synchronet þ Whiskey Lover's Amateur Radio BBS
  • From ARRL de WD1CKS@VERT/WLARB to QST on Fri May 29 17:36:00 2026
    05/29/2026

    Solar activity has remained at low levels this past week. The largest event of the period was a C3.4 flare originating from Region 4446.ÿ

    Solar activity has remained at low levels this past week. The largest event of the period was a C3.4 flare originating from Region 4446.ÿ ÿ There are nine numbered regions on the visible disk. Region 4452 showed notable growth and new flux emergence. Region 4450 decayed to plage, though unassociated transitory pores were observed to its east and west. Region 4443 decayed into a unipolar spot as it approached the west limb following the loss of its leading components. Regions 4453, 4454 and 4455 were numbered during the period. Far-side satellite imagery from Solar Orbiter indicates that Region 4455 is likely a large bipolar group with its trailing opposite-polarity spots still located behind the east limb and was numbered proactively due to its flaring potential. All other regions either continued in slow decay or remained stable. A faint, potentially partial-halo, coronal mass ejection (CME) first seen in LASCO C2 imagery on May 26 and subsequently in GOES/CCOR1 was analyzed. No obvious on-disk source exists. Modeling suggests a possible glancing blow at Earth on May 31. Additionally, narrow eruptions associated with flaring from newly numbered Region 4444 were seen in SUVI imagery but these features are well northward of the ecliptic plane with no Earth-directed components. No other Earth-directed coronal mass ejections (CMEs) were observed in available coronagraph imagery. ÿ Solar activity is expected to be at low to moderate levels through May 30. There remains a chance for isolated M-class flares (R1-R2/minor-moderate) driven by the eruptive potential of the southeast sunspot groups and newly numbered Region 4454. ÿ Solar wind parameters remained slightly elevated and possibly indicative of weak negative polarity coronal hole high-speed stream (-CH HSS)influences.ÿ ÿ Solar wind speeds varied modestly between 350 and 425 km/s. The phi angle was predominantly in the negative sector (towards the Sun), though minor deviations were observed later in the period. ÿ Solar wind parameters are expected to remain mildly enhanced due to weak coronal high speed stream (-CH HSS) influences through May 29. A return toward near-background, nominal conditions is anticipated by May 30. Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, May 28, 2026 ÿ Observations of the far side of the Sun by the Solar Orbiter probe showed us how a new and relatively large active region was approaching the northeastern limb of the solar disk. But it wasn't until it began to emerge on May 28 (designated as AR 4455) that it became clear the recent rise in solar activity would continue. Furthermore, the only significant coronal hole in the higher northern heliographic latitudes is sufficiently far from other active regions, so we need not expect a significant intensification of the solar wind. Therefore, we could expect calmer conditions in the Earth's magnetosphere and, at the same time, higher usable frequencies in the ionosphere for long-distance communications before their seasonal decline. However, summer in the ionosphere of the Earth's northern hemisphere, with higher attenuation in the lower ionosphere during the long days, will often be enlivened by sporadic E layers in the mid-latitudes until August. ÿ For more information concerning shortwave radio propagation, see
    http://www.arrl.org/propagation[1] and the ARRL Technical Information
    Service web page at, http://arrl.org/propagation-of-rf-signals[2]. For
    an explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[3] . Information and
    tutorials on propagation can be found at, http://k9la.us/[4] .

    Also, check this:

    https://bit.ly/3Rc8Njt[5]

    "Understanding Solar Indices" from September 2002 QST.


    [1] http://www.arrl.org/propagation
    [2] http://arrl.org/propagation-of-rf-signals
    [3] http://arrl.org/the-sun-the-earth-the-ionosphere
    [4] http://k9la.us/
    [5] https://bit.ly/3Rc8Njt
    ---
    þ Synchronet þ Whiskey Lover's Amateur Radio BBS
  • From ARRL de WD1CKS@VERT/WLARB to QST on Mon Jul 6 20:02:00 2026
    07/06/2026

    A series of M-class flares - all from Region 4479 - pushed solar activity to high levels this week. The largest of the flares was an M3.5 on July 1.
    ÿ
    An earlier flare from this region, M1.3 accompanied by a 1N H-alpha flare which peaked late July 1, appears to have been associated with dimming and a coronal mass ejection (CME) first identified in CCOR-1 imagery. Initial analysis suggests the CME has an Earth-directed component, although the speed derived from the available imagery was only 300-450 km/s. Further analysis is needed to increase confidence.
    ÿ
    Flux emergence and some consolidation around the leader and trailer spots was observed in Region 4479 during the period. Region 4478 produced an M8.5/2b flare on July 1 following occasional C-class flaring. This region also exhibited flux emergence in the intermediate spots and around the leader spot. Finally, Region 4480 was quiescent although some intermediate spots developed.
    ÿ
    Solar activity is likely to decrease to moderate levels (R1-R2, minor-moderate) with a slight chance for X-class flares (R3-strong), particularly from Region 4479.
    ÿ
    Solar wind parameters were enhanced with CME passage. Solar wind speeds have ranged from approximately 360 - 425 km/s. The CME from June 30 is expected to arrive early on July 3, bringing disturbed solar wind conditions that are expected to last into July 4. There is enough uncertainty around the CME timing that an arrival mid-to-late on July 2 is possible.

    Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, July 2, 2026, by F. K. Janda, OK1HH:

    Near the extensive active region AR4478, which the Solar Orbiter had been observing for several days before it rose on the southeastern limb of the solar disk, a small region, AR4479, was initially discovered. Both regions grew rapidly in the following days, while the configuration of their magnetic fields indicated nearby increased eruptive activity. High-energy flares occurred primarily on and after June 30, while some were accompanied by CMEs.

    Because the CMEs occurred near the solar central meridian, Earth was strongly affected by an intensified solar wind. Shortwave propagation conditions were favorable during the so-called positive phase of the disturbance on June 30, but very unfavorable during the negative phase on July 1. A similar pattern may recur in the coming days!

    The predicted Planetary A Index for July 7 to July 12 is 14, 5, 5, 12, 15, 12, and 8, with a mean of 10.1. The predicted Planetary K Index is 4, 2, 2, 4, 4, 4, and 3, with a mean of 3.3. Predicted 10.7 centimeter flux is 130, 125, 125, 125, 120, 125, and 120, with a mean of 124.3.

    For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[1]ÿand the ARRL Technical InformationÿService web page at,ÿhttp://arrl.org/propagation-of-rf-signals[2]. Forÿan explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[3]ÿ. Information and
    tutorials on propagation can be found at,ÿhttp://k9la.us/[4]ÿ.

    Also, check this:

    https://bit.ly/3Rc8Njt[5]

    "Understanding Solar Indices" from September 2002ÿQST.


    [1] http://www.arrl.org/propagation
    [2] http://arrl.org/propagation-of-rf-signals
    [3] http://arrl.org/the-sun-the-earth-the-ionosphere
    [4] http://k9la.us/
    [5] https://bit.ly/3Rc8Njt
    ---
    þ Synchronet þ Whiskey Lover's Amateur Radio BBS
  • From ARRL de WD1CKS@VERT/WLARB to QST on Fri Jul 10 23:10:00 2026
    07/10/2026

    Solar activity reached moderate levels with an M1.5/1N flare on July 8 from Region 4482.

    There are currently five numbered regions on the visible disk. Region 4482 demonstrated continued growth and developed a delta spot within its trailing spot group. Region 4485 displayed new flux emergence. Regions 4486 and 4487 were newly numbered during the period. Region 4481 was stable and remained an unremarkable unipolar group.

    No Earth-directed CMEs were observed in available coronagraph imagery.

    Solar activity is expected to remain at low levels through July 11, with a high chance for M-class (R1-R2/minor-moderate) flares and a slight chance for X-class (R3/strong and greater) events. This flare probability is almost entirely due to the complexity and potential of Region 4482.

    Solar wind parameters reflected near ambient background conditions. Solar wind speeds were generally near 400 km/s. The phi angle was predominantly in the positive sector.

    Enhancements are anticipated to begin on July 9 and continue through July 11 with the arrival of a co-rotating interaction region (CIR) ahead of a negative polarity coronal hole high-speed stream (-CH HSS).

    Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, July 9, 2026, by F. K. Janda, OK1HH:

    The power flux of solar radio noise at a frequency of 2800 MHz (at a wavelength of 10.7 cm), which is measured precisely every day at noon local time in Penticton, Canada, and is referred to as the "solar flux," remains at a relatively low level. The reason is that the number of observed sunspot groups on the solar disk dropped to just three on July 7, the lowest number recorded during a single solar rotation (the following day, their number increased to five). The largest active region, NOAA 4482, which we observe in the southeast of the solar disk, has not changed significantly in size and continues to produce moderate-intensity flares on a regular basis. All three coronal holes are currently relatively far from it. The intensity of the solar wind is changing only slightly; periods of increased geomagnetic activity alternate with quiet days, making it impossible to accurately predict future developments.

    A more pronounced increase in solar activity is expected in the second half of July (with a gradual increase in solar flux up to 180 s.f.u.). More significant geomagnetic activity can be expected if major solar flares occur, especially if they occur near or west of the central meridian. This is likely to happen sometime in the second half of July.

    The predicted Planetary A Index for July 11 to 17 is 12, 8, 5, 5, 5, 10, and 8, with a mean of 7.6. The predicted Planetary K Index is 4, 3, 2, 2, 2, 3, and 3, with a mean of 2.7. Predicted 10.7 centimeter flux is 125, 120, 125, 130, 135, 135, and 135, with a mean of 129.3.

    For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[1]ÿand the ARRL Technical InformationÿService web page at,ÿhttp://arrl.org/propagation-of-rf-signals[2]. Forÿan explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[3]ÿ. Information and
    tutorials on propagation can be found at,ÿhttp://k9la.us/[4]ÿ.

    Also, check this:

    https://bit.ly/3Rc8Njt[5]

    "Understanding Solar Indices" from September 2002ÿQST.


    [1] http://www.arrl.org/propagation
    [2] http://arrl.org/propagation-of-rf-signals
    [3] http://arrl.org/the-sun-the-earth-the-ionosphere
    [4] http://k9la.us/
    [5] https://bit.ly/3Rc8Njt
    ---
    þ Synchronet þ Whiskey Lover's Amateur Radio BBS
  • From ARRL de WD1CKS@VERT/WLARB to QST on Mon Jul 20 15:30:00 2026
    07/20/2026

    Solar activity has remained at low levels, with an occasional
    low-level C-class flaring observed, including a C3.3/Sf flare on July
    15 from Region 4489. The largest event of the period, a long-duration
    C8.9 flare that peaked on July 15, originated from a returning region
    on the eastern limb. This region is not yet numbered and will be
    assessed once it has become visible from Earth's perspective, but the
    latest imagery from Solar Orbiter suggested only a simple and rather
    average bipolar group with a relatively small penumbra.
    ÿ
    There are two numbered sunspot regions on the visible disk. Region
    4482 showed minor new flux emergence behind its mature primary spot,
    developing a bipolar configuration. As Region 4489 rotated further
    into view and limb foreshortening effects decreased, very small opposite-polarity trailing spots became visible, making it a stable
    bipolar group. Additionally, a small, magnetically simple, region
    tracked in Solar Orbiter imagery has begun to rotate over the east
    limb near S10. No Earth-directed CMEs were observed in available
    coronagraph imagery.
    ÿ
    Solar activity is expected to remain at low levels through July 18,
    with a slight chance for M-class (R1-R2/minor-moderate) flares,
    primarily driven by active regions anticipated to rotate onto the
    visible disk over the next few days.
    ÿ
    Solar wind parameters reflected possible combined glancing coronal
    mass ejection (CME) effects and subsequent weak positive polarity
    coronal hole high-speed stream (+CH HSS) influences.
    ÿ
    A return to more ambient-like conditions is expected over the next
    three days.

    Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
    Ionosphere,ÿ July 16, 2026, by F. K. Janda, OK1HH:

    The significant decline in solar activity throughout the first half
    of July is clearly illustrated by the solar flux values, which fell
    from 203 s.f.u. (July 2) to 100 s.f.u. (July 14-15), as well as by
    the number of sunspot groups, which dropped from five to two. A
    significant drop in the critical frequencies of the F2 layer began as
    early as July 4 during the geomagnetic disturbance of July 4-5, and
    due to the sharp decline in solar activity, these values returned to
    average levels only very slowly in the following days. Consequently,
    the sporadic E layer had an even greater impact on shortwave
    propagation (particularly in the mid-latitudes of Europe on July
    14-16).

    The increase in solar activity, which is expected to begin as early
    as the end of this week, while should last nearly until the end of
    the month, will result in significantly better shortwave propagation
    conditions than those experienced in the first half of the month.
    More significant changes (possibly an initial rise, but then very
    likely a temporary drop in MUF) will likely be caused by a
    geomagnetic disturbance, which is tentatively expected on July 21-22.

    The predicted Planetary A Index for July 18 to 24 is 5, 5, 5, 5, 12,
    10, and 7, with a mean of 7.0. The predicted Planetary K Index is 2,
    2, 2, 2, 4, 3, and 2, with a mean of 2.4. Predicted 10.7 centimeter
    flux is 135, 135, 135, 135, 135, 135, and 135, with a mean of 135.0.

    For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[1]ÿand the ARRL Technical InformationÿService web page at,ÿhttp://arrl.org/propagation-of-rf-signals[2]. Forÿan explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[3]ÿ. Information and
    tutorials on propagation can be found at,ÿhttp://k9la.us/[4]ÿ.

    Also, check this:

    https://bit.ly/3Rc8Njt[5]

    "Understanding Solar Indices" from September 2002ÿQST.


    [1] http://www.arrl.org/propagation
    [2] http://arrl.org/propagation-of-rf-signals
    [3] http://arrl.org/the-sun-the-earth-the-ionosphere
    [4] http://k9la.us/
    [5] https://bit.ly/3Rc8Njt
    ---
    þ Synchronet þ Whiskey Lover's Amateur Radio BBS
  • From ARRL de WD1CKS@VERT/WLARB to QST on Fri Jul 24 20:39:00 2026
    07/24/2026

    Solar activity continued at moderate levels as Region 4493 produced an M3.6 flare on July 22, which was the largest event of the period and was associated with a 10.7-centimeter radio burst of 200 solar flux units (sfu). Additionally, 4493 produced a C3.4 flare on July 22, which was associated with another 10.7-cm radio burst of 150 sfu.
    ÿ
    Region 4493 continued to undergo consolidation in its leading and trailing spots, but showed signs of new flux emergence in its intermediate area during the early hours of the reporting period. Region 4494 developed new, simple spots, but remained uni-polar. The remaining two numbered active regions were relatively stable and quiet.
    ÿ
    A filament eruption NW of Region 4493 on July 21 was modeled and assessed to be at least partially Earth-directed. While modeling efforts suggest that a bulk of the material should pass north and ahead of Earth s orbit, this is low confidence given the faintness of this event in Sun-Earth line-focused coronagraph imagery and compounded by likely interaction with the coronal hole in the vicinity of the source location.
    ÿ
    Additional M-class flare activity (R1-R2 radio blackouts) is likely through July 25 primarily due to the flare potential currently exhibited by AR 4493.
    ÿ
    Solar wind parameters were mildly enhanced under a sustained negative polarity coronal hole high-speed stream (CH HSS) regime and a possible secondary Co-rotating Interaction Region (CIR). Solar wind speeds were roughly between 400 and 482 km/s.
    ÿ
    The current regime is expected to largely continue through July 25. Additional enhancements are possible beginning late on July 23 due to a coronal mass ejection (CME) that left the sun on July 20, with stronger enhancements arriving by early on July 24 with the arrival of the aforementioned CME event from July 21.

    Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, July 23, 2026, by F. K. Janda, OK1HH:

    A relatively large sunspot group, which was already very conspicuous in images from the SOLAR ORBITER spacecraft, was designated NOAA 4493 after its discovery as an active region on the northeastern limb of the solar disk. It produced class C and M flares on a daily basis. It is currently located in the northwest of the solar disk. As it grew, it disrupted a long north-south coronal hole and remains the largest and most complex sunspot group on the visible disk, accounting for most of the observed eruptive activity. The eruption observed within it on July 20 was accompanied by a CME. The ejected particles triggered a geomagnetic disturbance on the afternoon of July 23.

    As a result of this activity, the ionosphere is currently undergoing variable conditions, characterized albeit irregularly by a pronounced presence of the summer sporadic E layer in the Earth s northern hemisphere. In the coming days, geomagnetic activity should begin to gradually decline (no earlier than July 25). Increased solar activity will likely persist almost until the end of the month. Conditions for ionospheric radio propagation will therefore remain variable, with irregular occurrences of relatively very favorable days.

    The predicted Planetary A Index for July 25 to 31 is 5, 5, 5, 5, 5, 5, and 5, with a mean of 5.0. The predicted Planetary K Index is 2, 2, 2, 2, 2, 2, and 2, with a mean of 2.0. The predicted 10.7 centimeter flux is 125, 125, 120, 118, 118, 115, and 112, with a mean of 119.0.

    For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[1]ÿand the ARRL Technical InformationÿService web page at,ÿhttp://arrl.org/propagation-of-rf-signals[2]. Forÿan explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[3]ÿ. Information and
    tutorials on propagation can be found at,ÿhttp://k9la.us/[4]ÿ.

    Also, check this:

    https://bit.ly/3Rc8Njt[5]

    "Understanding Solar Indices" from September 2002ÿQST


    [1] http://www.arrl.org/propagation
    [2] http://arrl.org/propagation-of-rf-signals
    [3] http://arrl.org/the-sun-the-earth-the-ionosphere
    [4] http://k9la.us/
    [5] https://bit.ly/3Rc8Njt
    ---
    þ Synchronet þ Whiskey Lover's Amateur Radio BBS
  • From ARRL de WD1CKS@VERT/WLARB to QST on Sun Aug 2 18:07:00 2026
    08/01/2026

    Solar activity has remained at low levels. Region 4494 exhibited decay in its trailing spots as its flare activity subsided. Region 4498 rotated into better viewing positioning, revealing mixed polarity just behind its large leading spot, and was responsible for a handful of low-level C-class flares.

    Region 4499 underwent evolution, gaining additional spots and producing a low-level C-class flare. Region 4501 rapidly emerged this period, developed rudimentary penumbra on its leading and trailing spots, produced a low-level C-class flare and was thus subsequently numbered. The remaining numbered active regions were unremarkable in relation.

    No Earth-directed CMEs were observed in available coronagraph imagery.

    Solar activity is expected to be low with a chance for M-class flares (R1-R2, minor-moderate) through August 1.

    Solar wind parameters were at nominal levels. Solar wind speeds roughly ranged from 310 km/s to 401 km/s. A disturbed solar wind environment will likely return July 30 due to the prospect of combined positive polarity coronal high speed stream (CH HSS) effects and coronal mass ejection (CME) arrivals from events that left the Sun on July 26 - 27. An additional disturbance is likely on August 1 with the arrival of an additional CME that left the Sun late on July 27.

    Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere, July 30, 2026, by F. K. Janda, OK1HH:

    During the last third of July, solar activity initially rose, while remained at a higher level until the end of the month. Although solar flares occasionally reached moderate intensity, while were exceptionally accompanied by coronal mass ejections, the Earth was not affected by them (though this could still happen by the end of July or early August, partly because there is a coronal hole in the southwestern part of the disk). There is only one active region on the far side of the Sun. Therefore, as the nine regions currently being observed fade, overall activity will decline shortly after the beginning of August.

    Shorter periods of increased geomagnetic activity may still occur in late July and at the beginning and end of the first third of August. Following the expected decline in solar activity, these will be followed at irregular intervals by shorter periods of deteriorated ionospheric conditions for shortwave propagation.

    The predicted Planetary A Index for July 31 to August 6 is 8, 5, 5, 5, 12, 15, and 10, with a mean of 8.6. The predicted Planetary K Index is 3, 2, 2, 2, 4, 3, and 3, with a mean of 2.7. Predicted 10.7 centimeter flux is 135, 130, 125, 125, 125, 120, and 125, with a mean of 126.4.

    For more information concerning shortwave radio propagation, see http://www.arrl.org/propagation[1]ÿand the ARRL Technical InformationÿService web page at,ÿhttp://arrl.org/propagation-of-rf-signals[2]. Forÿan explanation of numbers used in this bulletin, see http://arrl.org/the-sun-the-earth-the-ionosphere[3]ÿ. Information and
    tutorials on propagation can be found at,ÿhttp://k9la.us/[4]ÿ.

    Also, check this:

    https://bit.ly/3Rc8Njt[5]

    "Understanding Solar Indices" from September 2002ÿQST


    [1] http://www.arrl.org/propagation
    [2] http://arrl.org/propagation-of-rf-signals
    [3] http://arrl.org/the-sun-the-earth-the-ionosphere
    [4] http://k9la.us/
    [5] https://bit.ly/3Rc8Njt
    ---
    þ Synchronet þ Whiskey Lover's Amateur Radio BBS