SB PROP @ ARL $ARLP031

ARLP001 Propagation Forecast

ZCZC AP31
QST de W1AW
Propagation Forecast Bulletin 1 ARLP001

From ARRL Headquarters

Newington, CT July 31, 2026
To all radio amateurs

SB PROP ARL ARLP031
ARLP031 The ARRL Solar Report

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 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://www.arrl.org/propagation-of-rf-signals?utm_source=Informz&utm_medium=Email&utm_campaign=ARRL
] . For an explanation of numbers used in this bulletin, see www.arrl.org/the-sun-the-earth-the-ionosphere [ http://www.arrl.org/the-sun-the-earth-the-ionosphere?utm_source=Informz&utm_medium=Email&utm_campaign=ARRL
] . 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)


--- PyGate Linux v1.5.19
* Origin: Dragon's Lair, PyGate NNTP<>Fido Gate (3:633/10)