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The K7RA Solar Update


Over four days last week, we saw a blank Sun, starting with March 4. On March 5, the sunspot number was 11 (indicating a single sunspot), then on March 6-8 the Sun was blank again. Thus, we saw an average daily sunspot number of just 14.1, a 20-point drop from the previous seven days.

Yesterday (Thursday) still no sunspots (our reporting week for calculating averages runs Thursday through Wednesday, so the zero-sunspot number for Thursday will be included in the average for the March 17 bulletin).

Average daily solar flux decreased by seven points from 81.3 to 74.3.

Geomagnetic indicators increased, with average planetary A index rising from 13.1 to 20.9, and mid-latitude A index went from 8.7 to 15.

Predicted solar flux is 71 on March 10-12, 73 on March 13-16, 76 on March 17, 78 on March 18-23, 76 on March 24, 75 on March 25-29, 73 on March 30 through April 5, 72 on April 6-7, 74 on April 8-12, 76 on April 13, and 78 on April 14-19.

The planetary A index outlook shows 10 on March 10-11, 8 on March 12-15, then 20, 15, 10 and 8 on March 16-19, then 5, 8, 10, 15 and 8 on March 20-24, 5 on March 25-26, then 12, 35, 30, 20, 18, 12 and 8 on March 27 through April 2, 5 on April 3-4, 8 on April 5-6, 5 on April 7-10, then 10, 20, 15, 10 and 8 on April 11-15, and 5, 8, 10, 15 and 8 on April 16-20.

Geomagnetic activity forecast for the period March 10-April 5, 2017 from F.K. Janda, OK1HH, of the Czech Propagation Interest Group.

"Geomagnetic field will be:

Quiet on March 14-15, 21, 26

Mostly quiet on March 10-13, 20

Quiet to unsettled March 16, 22, 25, April 4

Quiet to active on March 18-19, 24, 27-29, 31, April 1-3, 5

Active to disturbed on March 17, 23, 30

Amplifications of the solar wind from coronal holes are expected on March (20-22,) 23-27, (April 3-8)

- Parenthesis means lower probability of activity enhancement and/or lower reliability of prediction."


Jon Jones, N0JK, sent a tip about a 10-meter opening last weekend from 1809-1839 UTC: “There was an unusual 10-meter opening in the ARRL DX SSB contest last weekend between Bermuda and W1, W2, W3 and W4 early Sunday afternoon. Kurt, VP9/W6PH, was in Bermuda at VP9GE's station for the contest.

“Kurt related ‘I decided to listen to the beacons on 10 meters and heard one in FN32. I decided to try a CQ on 28.401 MHz and, lo and behold, a very loud K3OO came back to me and said he saw the blip on his panadapter. He said he would spot me and that started the ball rolling.’

“Kurt then made over 400 contacts on 10 meter SSB with strong signals. The distance, high signal strength and time of day suggest the propagation was one-hop Sporadic-E. Kurt noted no contacts to the west coast of North America on 10, which would have been F-layer. Sporadic-E can occur in March, though it is rare. The month of March has the lowest amount of Sporadic-E propagation of any month in North America. The 10-meter Sporadic-E opening was an unexpected treat for Kurt and significantly helped his score.”

Jon sent a map from showing the impressive opening from 1809-1839 UTC on March 5. It showed a tangle of contacts from North America to Caribbean, but I redid it on the web site specifying a World Map, and it showed contacts all the way down to 54 degrees south latitude, around the southern tip of South America. Try it out yourself.


David Moore sent a photo taken in Norway of an aurora that was gone in about 10 seconds! See it:


W9WS sent this, about an experiment regarding space weather on the International Space Station. I’m pretty sure that the Steven Powell mentioned in this article is N2BU:


Stan Tacker, N5OHM, wrote: “Always appreciate your info. Yes 10 meters has been opening up from North American to South America. The window is usually short, but when it is open, it’s gangbusters. It reminds me of the days when guys ran scanners monitoring 10-meter FM repeaters to hear the band open up.”


For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of numbers used in this bulletin, see

An archive of past propagation bulletins is at More good information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve overseas locations are at Instructions for starting or ending email distribution of ARRL bulletins are at

Sunspot numbers for March 2 through 8, 2017 were 52, 36, 0, 11, 0, 0, and 0, with a mean of only 14.1. 10.7 cm flux was 79.1, 78, 75.2, 72.8, 72.4, 71.7, and 70.6, with a mean of 74.3. Estimated planetary A indices were 32, 22, 22, 17, 25, 16, and 12, with a mean of 20.9. Estimated mid-latitude A indices were 23, 15, 18, 11, 16, 13, and 9, with a mean of 15.