SB PROP @ ARL $ARLP003<br />ARLP003 Propagation de K7RA<br /><br />ZCZC AP03<br />QST de W1AW <br />Propagation Forecast Bulletin 3 ARLP003<br />From Tad Cook, K7RA<br />Seattle, WA January 21, 2005<br />To all radio amateurs <br /><br />SB PROP ARL ARLP003<br />ARLP003 Propagation de K7RA<br /><br />This has been a very active week for solar flares and geomagnetic<br />storms. Average daily sunspot number rose over 57 points this week<br />to 89, and average daily solar flux was up nearly 43 points to<br />132.7, when compared to the previous week. The average daily<br />planetary A index more than doubled, from 17.9 to 36.6.<br /><br />Huge sunspot 720 provided lots of excitement over the past week.<br />Clay Evans from Colorado wrote to say that on January 14 he was<br />driving to work near Boulder, and through the heavily filtered<br />clouds he could see a large dark spot on the sun. This was probably<br />sunspot 720.<br /><br />Two large flares erupted from this sunspot on Saturday, January 15.<br />Over the next few days the geomagnetic numbers bumped up<br />dramatically, with a planetary A index for January 17-19 of 63, 72<br />and 62. The high latitude collage A index was 114, 136 and 106 for<br />those same three days.<br /><br />On Monday, January 17 another big flare blasted in our direction.<br />It peaked around 0950z. As sunspot 720 moves off the center of the<br />visible solar disk, more flares erupted, including a huge X7-class<br />event on Thursday, January 20. The energy could sweep past earth<br />today (January 21). This flare was the largest of the past year and<br />triggered the largest radiation storm in the current 11 year solar<br />cycle.<br /><br />This radiation storm hasn't yet resulted in a geomagnetic storm here<br />as of the writing of this bulletin on Thursday night. Currently the<br />prediction is for a planetary A index of 25, 20 and 20 for January<br />21-23, but this could be higher depending on how direct the<br />radiation hits earth. With sunspot 720 moving beyond view, daily<br />solar flux values are expected to dip below 100 around January<br />23-24.<br /><br />If you would like to comment or have a tip, email the author at,<br />k7ra@arrl.net.<br /><br />For more information concerning propagation and an explanation of<br />the numbers used in this bulletin see the ARRL Technical Information<br />Service propagation page at,<br />http://www.arrl.org/tis/info/propagation.html.<br /><br />Sunspot numbers for January 13 through 19 were 77, 65, 100, 99, 107,<br />109 and 66 with a mean of 89. 10.7 cm flux was 115.6, 129.8, 144.9,<br />144.5, 137.5, 124.3 and 132.5, with a mean of 132.7. Estimated<br />planetary A indices were 13, 12, 22, 12, 63, 72 and 62 with a mean<br />of 36.6. Estimated mid-latitude A indices were 10, 11, 11, 10, 27,<br />35 and 31, with a mean of 19.3.<br />NNNN<br />/EX