SB PROP @ ARL $ARLP014
ARLP014 Propagation de K7RA

ZCZC AP14
QST de W1AW  
Propagation Forecast Bulletin 14  ARLP014
From Tad Cook, K7RA
Seattle, WA  April 7, 2023
To all radio amateurs 

SB PROP ARL ARLP014
ARLP014 Propagation de K7RA

Average solar flux and sunspot numbers were way down this week.
Sunspot numbers were down by half, from 112.6 last week to 53.4.
Average daily solar flux declined from 156.1 to 132.5.
 
Geomagnetic indicators were lower too.  Average daily planetary A
index from 23.3 last week to 15 in this bulletin, and average daily
middle latitude A index from 13.7 to 11.7.
 
The April 1 middle latitude A index of 11 is my guess.  The middle
latitude A index for April 1 was not available.
 
Predicted solar flux is 140 on April 7 and 8, 135 on April 9 to 11,
140, 145 and 130 on on April 12 to 14, 130 on April 14, 135 on April
15 to 17, 140 on April 18 to 20, 135 on April 21 to 23, then 130,
125 and 120 on April 24 to 26, 115 on April 27 to 29, 125 on April
30, 120 on May 1 and 2, 115 on May 3 and 4, then 110 on May 5 to 7,
and 115, 120, 125 and 130 on May 8 to 11, then 135 on May 12 to 14,
and 140 on May 15 to 17.
 
Predicted planetary A index is 5 on April 7 to 10, then 8, 8 and 5
on April 11 to 13, 8 on April 14 and 15, then 12, 10 and 15 on April
16 to 18, then 5, 20, 15 and 10 on April 19 to 22, 5 on April 23 to
25, then 15 and 18 on April 26 and 27, 15 on April 28 and 29, 8 on
April 30, 10 on May 1 and 2, 8 on May 3, then 5 on May 4 to 6, then
12, 10, 8 and 5 on May 7 to 10, 8 on May 11 and 12, then 10, 12, 15,
5 and 20 on May 13 to 17.
 
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's
Ionosphere -- April 6, 2023 from F.K. Janda, OK1HH.
 
"On March 29, another solar flare of category X1.2 was observed.  It
came from the AR3256 sunspot group near the southwestern limb of the
Sun.
 
This year, in just three months, we've already seen seven X-class
flares, the same as all of last year.  There are still about two
years to go before the cycle peak.
 
On the morning of March 31, a solar wind stream hit Earth,
triggering a minor G1-class geomagnetic storm.  A relatively quiet
weekend followed.
 
Then new sunspot group AR3270 emerged in the southern part of the
solar disk.  It grew rapidly, its two dark cores, larger than Earth,
indicating an unstable magnetic field.  If they merge an eruption
would likely follow.  It would probably be a geoeffective eruption
because the sunspot was directly opposite the Earth.
 
After the AR3270 sunspot group dips behind the southwestern limb of
the solar disk this weekend, there should be a temporary drop in
overall solar activity, accompanied by a string of geomagnetically
quieter days.
 
As the irregular occurrence of higher geomagnetic activity results
in irregular changes in shortwave propagation conditions, the
subsequent evolution should be more regular and predictable."
 
This video from Tamitha Skov came out right after last week's
bulletin:
 
https://youtu.be/F8ERhLiOK88
 
More sun fun:
 
https://youtu.be/VWhhSWjDJtw
 
https://bit.ly/41aolq2
 
Don't worry:
 
https://bit.ly/3zCtg74
 
On April 5 from 1723 to 1746 UTC, Tom, WA1LBK in Fall River,
Massachusetts copied HC1MD/2 in Ecuador on 6 meter FT8.  Check HC1MD
on QRZ.com for some beautiful photos by Rick, NE8Z.
 
https://bit.ly/3zBm5wa
 
This weekend is the CW portion of the Japan International DX
Contest.
 
See http://jidx.org/
 
Send your tips, reports, observations, questions and comments to
k7ra@arrl.net.  When reporting observations, don't forget to tell us
which mode you were operating.
 
For more information concerning shortwave radio propagation, see
http://www.arrl.org/propagation and the ARRL Technical Information
Service at http://arrl.org/propagation-of-rf-signals .  For an
explanation of numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere .
 
An archive of past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation .  More good
information and tutorials on propagation are at http://k9la.us/ .
 
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins .
 
Sunspot numbers for March 30 through April 5, 2023 were 99, 61, 23,
54, 56, 44, and 37, with a mean of 53.4.  10.7 cm flux was 140.3,
129.3, 125.3, 126.9, 133.6, 135.7, and 136.6, with a mean of 132.5.
Estimated planetary A indices were 17, 21, 13, 15, 15, 13, and 11,
with a mean of 15.  Middle latitude A index was 11, 17, 11, 13, 11,
10, and 9, with a mean of 11.7.
NNNN
/EX