TZUTC: -0500   
   MSGID: 526.fidonet-ls_arrl@1:2320/33 28fafe6a   
   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 $ARLP025   
   ARLP025 Propagation de K7RA   
      
   ZCZC AP25   
   QST de W1AW    
   Propagation Forecast Bulletin 25  ARLP025   
   From Tad Cook, K7RA   
   Seattle, WA  June 23, 2023   
   To all radio amateurs   
      
   SB PROP ARL ARLP025   
   ARLP025 Propagation de K7RA   
      
   Sunspot numbers and solar flux rose this week. There were two new   
   sunspot groups on June 15, another on June 17 and one more on June   
   18, three more on June 19, two more on June 20 and another on June   
   21.   
      
   Average daily sunspot number increased from 122 to 143, and average   
   daily solar flux rose from 154.8 to 165.4.   
      
   Average daily planetary A index jumped from 5.7 to 15.4, while the   
   middle latitude numbers increased from 6.7 to 13.1.   
      
   Predicted solar flux is 180 on June 23-24, 185 on June 25-27, 180 on   
   June 28, 175 on June 29 through July 1, 180 on July 2-3, 175 on July   
   4-5, 170 on July 6-10, then 165 on July 11, 160 on July 12-13, 165   
   on July 14-15, 160 and 155 on July 16-17, 160 on July 18-19, 165 on   
   July 20-24, 170 on July 25, 175 on July 26-28, and 180 on July   
   29-30.   
      
   Predicted planetary A index is 14, 10 and 8 on June 23-25, then 5,   
   5, and 12 on June 26-28, then 5, 5, and 12 again on June 29 through   
   July 1, 8 on July 2, 5 on July 3-7, 12 on July 8, 5 on July 9-11,   
   then a dramatic increase to 20 and 30 on July 12-13, 8 on July   
   14-15, and 12 on July 16-17, 10 on July 18, 5 on July 19-23, 12 on   
   July 24-25, 5 on July 26-27, 12 and 8 on July 28-29, and 5 on July   
   30 through August 3.   
      
   These predictions are from forecasters Liming and Dethlefsen of the   
   US Air Force 557th Weather Wing at Offutt AFB.   
      
   See https://bit.ly/3qRNJnr   
      
   So, what does this forecast show for ARRL Field Day, which is this   
   weekend?   
      
   Geomagnetic numbers are a bit more unsettled than what was shown in   
   last week's bulletin, which had an A index of 5 for Friday through   
   Sunday. The latest shows 14, 10 and 8. Predicted solar flux looks   
   excellent, at 180, 180 and 185.   
      
   Of course, Field Day does not begin until Saturday, but here we also   
   include data for the day prior.   
      
   X1.1 solar flare:   
      
   https://bit.ly/3CI0OCA   
      
   Another report from South Asia regarding solar flares as some sort   
   of existential threat.  Don't worry. Nothing terrifying about what   
   they report, but there is a nice description of what the SOHO   
   observatory does.   
      
   https://bit.ly/444VhSk   
      
   https://soho.nascom.nasa.gov   
      
   Reader David Moore shared this video:   
      
   https://www.space.com/earth-sunlight-dance-solstice-video   
      
   Don't know why, but no weekly report from OK1HH this time around.   
      
   On Thursday I attended an online event, the "Space Weather   
   Enterprise Forum," thanks to a tip from K6PFA.   
      
   Most of the sessions concerned threats from solar flares, but there   
   was great commentary from Bill Murtaugh of NOAA's Space Weather   
   Prediction Center.   
      
   He noted that the current solar cycle should peak in summer 2024   
   instead of 2025 and will peak much stronger than the consensus   
   forecast from earlier in the cycle. He also noted that increased   
   flare activity always occurs in the years following a sunspot cycle   
   peak.   
      
   John Dudley, Managing Director of Flight Operations at American   
   Airlines gave an interesting presentation about how space weather   
   affects routing of international flights.   
      
   He mentioned their expert on space weather at the airline, and I   
   looked him up. Yes, a ham, KC1ENP. Could not find an email address   
   for him, so I sent a QSL card to make contact.   
      
   Thanks to https://spaceweather.com/ for this fascinating article about   
   setting up a personal space weather station.  It is under the   
   heading, "A New Way To Detect Solar Flares":   
      
   https://essd.copernicus.org/articles/15/1403/2023/   
      
   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 June 15 through 21, 2023 were 112, 120, 110,   
   133, 181, 155, and 190, with a mean of 143. 10.7 cm flux was 153.1,   
   157.2, 158.1, 164.1, 168.8, 180.1, and 176.4, with a mean of 165.4.   
   Estimated planetary A indices were 24, 38, 8, 10, 10, 10, and 8,   
   with a mean of 15.4. Middle latitude A index was 17, 24, 8, 12, 9,   
   13, and 9, with a mean of 13.1.   
   NNNN   
   /EX   
   --- SBBSecho 3.20-Win32   
    * Origin: The Thunderbolt BBS - Little Rock, Arkansas (1:2320/33)   
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   SEEN-BY: 135/300 153/7715 154/10 30 40 50 700 218/700 840 220/70 90   
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