TZUTC: -0500   
   MSGID: 617.fidonet-ls_arrl@1:2320/33 29297484   
   PID: Synchronet 3.20a-Win32 master/777fb6d8b Jun 13 2023 MSC 1929   
   TID: SBBSecho 3.20-Win32 master/777fb6d8b Jun 13 2023 MSC 1929   
   BBSID: TBOLT   
   CHRS: ASCII 1   
      
   SB PROP @ ARL $ARLP030   
   ARLP030 Propagation de K7RA   
      
   ZCZC AP30   
   QST de W1AW     
   Propagation Forecast Bulletin 30  ARLP030   
   From Tad Cook, K7RA   
   Seattle, WA  July 28, 2023   
   To all radio amateurs    
      
   SB PROP ARL ARLP030   
   ARLP030 Propagation de K7RA   
      
   Average daily sunspot numbers declined slightly over the past week   
   (July 20-26) to 128.1, compared to 130.6 over the previous seven   
   days.   
      
   Average daily solar flux declined significantly from 190.5 to 172.2.   
      
   The solar flux forecast sees values at 165 and 162 on July 28-29,   
   158 on July 30-31, then 155 on August 1-3, then 165, 170 and 175 on   
   August 4-6, 180 on August 7-10, 175 on August 11-13, 180 on August   
   14-15, 175 on August 16-18, 170 on August 19, then 165, 165 and 160   
   on August 20-22, and 155 on August 23-26, 160 on August 27, 165 on   
   August 28-30, 170 and 175 on August 31 through September 1, and 180   
   on September 2-6.   
      
   Predicted planetary A index is 5 on July 28-29, 15 and 10 on July   
   30-31, 5 on August 1-3, 8 on August 4, 5 on August 5-9, 10 on August   
   10, 8 on August 11-13, 5 on August 14-19, then 10, 8 and 5 on August   
   20-22, 12 on August 23-24, 10 on August 25-26, 5 on August 27-29, 10   
   and 8 on August 30-31, and 5 on September 1-5.   
      
   Weekly Commentary on the Sun, the Magnetosphere, and the Earth's   
   Ionosphere -- July 27, 2023 from OK1HH.   
      
   "The likelihood of more massive solar flares has slowly decreased in   
   recent days as large groups of spots have fallen behind the western   
   limb of the solar disk and the magnetic configuration of the    
   remaining regions has become increasingly simple over the past few   
   days.   
      
   On July 20 and 21, two CMEs struck Earth's magnetic field in   
   accordance with the prediction. However, both impacts were weak and   
   did not produce even a minor geomagnetic storm.   
      
   Another weak halo CME was expected to leave the Sun on 23 July at   
   about 1530 UTC in a C5 class flare in spot group AR3376, coinciding   
   with the outburst of a relatively nearby magnetic filament. The   
   Earth's magnetic field detected its arrival at 0200 UTC on 26 July.   
   The result was an increase in geomagnetic activity and a   
   deterioration of shortwave propagation conditions. The disturbance   
   actually started on 25 July at 2235 UTC, but it was not clear   
   whether it was an early arrival of the same CME or another one that   
   we did not detect.   
      
   Note: since I will be abroad next week, I will not post the next   
   comment on August 3, but on August 10."   
      
   Sunspots, flares and aurora.  https://bit.ly/44JxcRp   
      
   Mars Rover sees the far side of the sun.  https://bit.ly/3KbRV8b   
      
   Rocket punches hole in ionosphere.  https://bit.ly/3KceBFB   
      
   Nearly five decades ago I witnessed the same thing, viewed from   
   Marin County, California. It was a huge dramatic display, My friend   
   had seen it before, and said it was created by a rocket launch from   
   Vandenberg AFB in Southern California.   
      
   Another CME.  https://bit.ly/44LhRjx   
      
   On July 27, Spaceweather.com sent this alert:   
      
   "A STRONG FARSIDE CME JUST HIT SOLAR ORBITER: Europe's Solar Orbiter   
   just got hit by the kind of CME that may have once caused a major   
   power blackout on Earth. This time, Earth was not in the line of   
   fire. It was a farside eruption that flew away from our planet.   
   Maybe next time?"   
      
   Massive flare?  https://bit.ly/3Ya7OSC   
      
   Latest from Dr. Tamitha Skov.  https://youtu.be/cD5VbWvBXsE   
      
   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 .   
      
   Also, check this article from September, 2002 QST:   
      
   https://www.arrl.org/files/file/Technology/tis/info/pdf/0209038.pdf   
      
   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 July 20 through 26, 2023 were 131, 121, 103,   
   117, 141, 137, and 147, with a mean of 128.1  10.7 cm flux was   
   184.3, 172.8, 174.4, 172.5, 165.1, 169, and 167.4, with a mean of   
   172.2. Estimated planetary A indices were 10, 13, 9, 6, 7, 11, and   
   21, with a mean of 11. Middle latitude A index was 10, 11, 9, 5, 8,   
   12, and 23, with a mean of 11.1.   
   NNNN   
   /EX   
   --- SBBSecho 3.20-Win32   
    * Origin: The Thunderbolt BBS - Little Rock, Arkansas (1:2320/33)   
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