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The K7RA Solar Update


Sunspots have been coming and going, and now this week they returned. The spots that returned didn't last long, though.

No sunspots were seen from January 31 through March 4, then from March 13-17, and again March 25-30. They returned on Sunday, March 31 but only lasted four days, through Wednesday, April 3. Sunspot numbers over that period were 14, 17, 18 and 17.

Average daily sunspot numbers declined from 16 in last week’s report to 9.4 this week. Average daily solar flux declined from 75.2 to 69.5. Average daily planetary A index rose from 3.7 to 8.4, while average middle latitude A index went from 3.9 to 7.3.

Predicted solar flux is 70 on April 5-11, 69 on April 12-13, 70 on April 14-22, then 69, 68, 69 and 69 on April 23-26, 70 on April 27 through May 7, 69 on May 8-10, and 70 on May 11-19.

Predicted planetary A index is 12, 10, 12 and 8 on April 5-8, 5 on April 9-11, then 15 and 8 on April 12-13, 5 on April 14-23, then 10, 8, 5, 8, 10 and 8 on April 24-29, 10 on April 30 through May 1, 8 on May 2-3, 10 on May 4, 5 on May 5-8, then 15 and 8 on May 9-10, and 5 on May 11-19.


In last week’s bulletin ARLP013 we presented a message from Dr. Tamitha Skov, WX6SWW in which she complained about overhyped space weather stories in the mainstream press. I think we may have seen another example this week from a British tabloid:

This was published on Wednesday when the planetary A index was slightly unsettled at 12, on Thursday it was 8, and predicted values of 12, 10, 12 and 8 follow on April 5-8 and 5 on April 9-10. This is not expected to cause blow outs of “electrical transformers and power stations,” as mentioned in the article, nor “leave people vulnerable to cancer”.

The story was picked up by another UK publication:

Note they quote predicting only “a minor stream of solar wind.”

The Washington Post also addressed this issue:


F.K. Janda, OK1HH sends us his geomagnetic activity forecast for the period April 5 until May 1, 2019.

Geomagnetic field will be:

Quiet on April 9, 14, 17-19,

Quiet to unsettled on April 5-8, 16, 20, 26,

Quiet to active on April (15, 21-23,) 24, 27-29, May 1

Unsettled to active on April (10 -) 11, 13, 25, 30

Active to disturbed April (12)

Solar wind will intensify on April (6,) 12-13, 15-16, (19-22,) 23-24, (25-30, May 1)

Parenthesis means lower probability of activity enhancement.


Mike Schaeffer, KA3JAW in Easton, Pennsylvania wrote on Thursday night: “Spring season high frequency band Es is slowly emerging out of its dormant state. On Friday, April 5, 0100 UTC (Thursday, April 4, 9:00 PM EDT local) I was monitoring the 11-meter Citizen Band (27 MHz) and noticed a swooshing, light fading condition on channel 28, which is normally inactive. Suddenly, like a flick of a light switch, Es emerged from the states of Georgia, Alabama, Louisiana. The average distance from Easton, Pennsylvania was about 1,000 miles. Activity lasted for a brief time of about ten minutes. This occurred one hour, 32 minutes after local sunset (7:28 PM). According to reports, the 10.7cm flux was 70.”


Thanks to John Pieszcynski, W2FV of Trout Lake, Washington for his tip on problems with satellite debris during solar minimum, from Dr. Tony Phillips of


At 2345 UTC on Monday, April 1 Steve Sacco, NN4X in Florida sent this query about something I had otherwise heard nothing about: “Is there some kind of solar event going on?  I don't see anything of note at Several folks across the U.S. are hearing an extremely broad-band noise on 30 meters. I'm not able to peak it from any heading with my 2-element Yagi.”


Here is the latest video from Dr. Skov:


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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 28 through April 3, 2019 were 0, 0, 0, 14, 17, 18, and 17, with a mean of 9.4. 10.7 cm flux was 68.4, 68.8, 69.4, 69.5, 69.3, 70.8, and 70.6, with a mean of 69.5. Estimated planetary A indices were 11, 7, 4, 11, 8, 6, and 12, with a mean of 8.4. Middle latitude A index was 10, 6, 3, 9, 6, 5, and 12, with a mean of 7.3.





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