SB PROP @ ARL $ARLP019   
   ARLP019 Propagation de K7RA   
      
   ZCZC AP19   
   QST de W1AW   
   Propagation Forecast Bulletin 19  ARLP019   
   > From Tad Cook, K7RA   
   Seattle, WA  May 6, 2016   
   To all radio amateurs   
      
   SB PROP ARL ARLP019   
   ARLP019 Propagation de K7RA   
      
   Solar activity increased last week, making one of those occasional upticks on   
   the way down from the peak of the solar cycle.   
      
   Average daily sunspot numbers increased from 43.3 to 74.7, and average daily   
   solar flux increased by 10 points to 91.9. Average planetary A index went from   
   9.4 to 11.3 and average mid-latitude A index went from 11.6 to 10.7.   
      
   At 0415 UTC on May 2 the Australian Space Forecast Centre issued a geomagnetic   
   disturbance warning. At the end of the day, the planetary A index was 31,   
   indicating a geomagnetic storm.   
      
   The latest forecast has solar flux at 90 on May 6, 85 on May 7-12, 90 on May   
   13, 95 on May 14-15, 90 on May 16, 82 on May 17-22 and 85 on May 23, 90 on May   
   24, 95 on May 25-28, then 90, 95 and 105 on May 29-31, 110 on June 1-2, 105 on   
   June 3, 100 on June 4-6, and 95 on June 7-11. Solar flux is forecast to drop   
   below 90 on June 12 and beyond.   
      
   Predicted planetary A index is 8 on May 6, 12 and 18 on May 7-8, 25 on May   
   9-10, then 20 on May 11, 8 on May 12-13, 12 on May 14 and 5 on May 15-18, and   
   12, 15, 12, 8, 5 and 10 on May 19-24, and 5 on May 25-27. The next active days   
   are June 6-8, when the planetary A index is expected to be 18, 25 and 20.   
      
   The OK1HH geomagnetic activity forecast for the period May 6-June 1, 2016.    
   The geomagnetic field will be:   
      
   Quiet on May 7-8, 16-17, 26-28, June 1 Mostly Quiet on May 9, 14, 18, 22, 29,   
   31 Quiet to Unsettled on May 6, 13, 21, 23-25 Quiet to Active on May 12, 15,   
   19-20 Active to Disturbed on May 10-11, 30   
      
   Increases in the solar wind from coronal holes are expected on May 7, 12-14,   
   (17,) 22-26, 31, and June 1.   
      
   Parenthesis means lower probability of activity enhancement.   
      
   David Moore sent a link to an article titled, "Spectacular Solar Flare   
   Captured in New NASA Video." The link is, http://huff.to/236Xxl8 .  The flare   
   occurred on April 17. That day, the high latitude College A index (measured at   
   Fairbanks, Alaska) was 33. But a few days earlier the index was higher, at 45   
   and 47 on April 13-14.   
      
   As the season shifts toward Summer, you may notice some changes in HF   
   propagation. For instance, on 15 meters from California to Japan, back at the   
   Vernal Equinox you would see good strong signals, with openings beginning   
   around 2100 UTC and fading out around 0430 UTC. The path should be open   
   75-100% of the time from 2130-0300 UTC. But by the middle of this month you   
   might see signals several dB lower and the path not as robust, with the   
   probability of openings being more toward the 50-75% range. Openings would   
   begin around 2000 UTC and signals should start getting weaker after 0300 UTC.   
      
   On 40 meters over the same path at the Vernal Equinox (around March 23) we   
   would see the band start to open after 0630 UTC with strong signals through   
   the night until around 1530 UTC. But by the middle of May, the period that   
   this path is open is much shorter, starting around 0830 UTC and fading out   
   after 1400 UTC.   
      
   Looking the other direction, from California to Atlanta, Georgia during the   
   Spring, the strongest 40 meter signals over that path would be between   
   0230-1200 UTC. But by the middle of May that opening would shift to 0300-1030   
   UTC.   
      
   You can play with these numbers yourself, varying seasons, locations and   
   frequencies by using a propagation prediction program. A free one, W6ELprop,   
   is available from K9LA. His web site is http://k9la.us/ and he has lots of   
   useful information on radio propagation. The link to propagation programs is   
   at http://k9la.us/html/tutorials.html .  An alternate source is at   
   http://brucerichards.com/army/w6elprop.htm .   
      
   If you would like to make a comment or have a tip for our readers, email the   
   author at k7ra@arrl.net.   
      
   For more information concerning radio propagation, see the ARRL Technical   
   Information Service web page at, http://arrl.org/propagation-of-rf-signals.   
   For an explanation of the numbers used in this bulletin, see htt   
   ://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/.   
      
   Monthly propagation charts between four USA regions and twelve overseas   
   locations are at http://arrl.org/propagation.   
      
   Instructions for starting or ending email distribution of ARRL bulletins are   
   at http://arrl.org/bulletins.   
      
   Sunspot numbers for April 28 through May 4 were 84, 82, 82, 76, 75, 57, and   
   67, with a mean of 74.7. 10.7 cm flux was 94.9, 92.4, 94, 92.2, 89.8, 90, and   
   90.1, with a mean of 91.9. Estimated planetary A indices were 5, 4, 7, 16, 31,   
   11, and 5, with a mean of 11.3. Estimated mid-latitude A indices were 6, 3, 9,   
   16, 26, 11, and 4, with a mean of 10.7.   
      
   NNNN   
   /EX   
      
   )\/(ark   
      
   Always Mount a Scratch Monkey   
      
   ... Whoever decided to cut taglines at 70 characters can kiss my rosy red   
   ---   
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