ARRL
04/24/2020
The last day with a visible sunspot was April 4.
Over the past reporting week, April 16-22, average daily solar flux was 69, down a half point from the previous week, when the average was 69.5.
Average daily planetary A index was 7.3 while mid-latitude A index was 7. This was up from 6.1 and 5, mainly due to the first geomagnetic storm of 2020, which pushed planetary A index to 18 on April 19. That event bumped up the average.
Solar flux numbers have been soft of late, with averages over recent weeks of 71.1, 69.4, 70.2, 69.5 and now 69. Lower solar flux probably means less radiation that might excite the ionosphere.
Predicted solar flux is 71 on April 24-30 and 69 on May 1 through June 7. The April 23 forecast shows predicted solar flux at 96 on May 12, but we’ve seen this error once in the past. The digits were transposed. In fact, I won’t even notify NOAA. It will be fun to see how long it takes for anyone to notice.
The predicted planetary A index is forecast at 5 on April 24-29, 8 on April 30, 5 on May 1-4, 12 on May 5, 5 on May 6-16, then 12, 10, 8 and 10 on May 17-20, 5 on May 21-23, then 10, 5, 5 and 8 on May 24-27, 5 on May 28-31, 12 on June 1, and 5 on June 2-7.
Geomagnetic activity forecast for the period April 24-May 19, 2020 from F.K. Janda, OK1HH.
Geomagnetic field will be:
Quiet on: May 1-3, 6, 13-15, 19
Quiet to unsettled on: April 24, 28, 30. May 18
Quiet to active on: (April 25,¨27, May 5, 7-9, 12, 17)
Unsettled to active on: (April 26, 29, May 4, 10-11, 16)
Active to disturbed: nothing expected
Solar wind will intensify on April 17-19, (20,) 26-28, May 4-6, 8-10
- Parenthesis means lower probability of activity enhancement.
- The predictability of changes remains lower as there are no indications.
Frank, W3LPL alerted us to an updated Cycle 25 prediction: "Early this month SWPC published their official updated prediction of Solar Cycle 25 in a new user-interactive graph format. Their updated prediction is based on the results of NOAA's Solar Cycle 25 Prediction Panel. See www.swpc.noaa.gov/products/solar-cycle-progression.
“SWPC forecasts a solar maximum between 105 and 125 with the peak occurring between November 2024 and March 2026. There is broad consensus that Solar Minimum is ongoing this year -- or may have already occurred -- and that Cycle 25 will have no major change in the level of solar activity compared to Cycle 24.
“For many years SWPC's solar cycle predictions have used the Royal Observatory of Belgium's International Sunspot Number. SWPC's official solar cycle prediction now uses the SWPC sunspot number. The International Sunspot Number is typically about one third lower than the SWPC sunspot number.
“While this is SWPC's official Cycle 25 prediction, it’s important to note there is still divergence among various forecasting methods and members of the space weather forecasting community. Most forecasts and forecasters agree that the Cycle 25 peak is likely to be within plus or minus 20 percent of Cycle 24 and is likely to occur between 2024 and 2027. Also see link.springer.com/article/10.1007/s41116-020-0022-z/tables/2.”
N0JK reported from Kansas: "I had sporadic-E on 50 MHz April 21. From 1900-2100z stations in Florida were coming in well. I made about a dozen contacts on FT8. Also decoded CO8LY FL20 calling CQ. Then I saw on the PSKReporter site that two Kansas stations copied HC5VF in Ecuador on 6 Meter FT8 around 2310z. This was likely via multi-hop sporadic-E."
Dr Tamitha Skov, WX6SWW has a new video report: https://www.youtube.com/watch?v=QmfS7P1pJMQ
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 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.
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 16 through 22, 2020 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 68.5, 67.9, 69.8, 68.6, 68.2, 69.1, and 70.7, with a mean of 69. Estimated planetary A indices were 5, 4, 4, 3, 18, 9, and 8, with a mean of 7.3. Middle latitude A index was 5, 4, 4, 2, 16, 8, and 10, with a mean of 7. (arrl.org)
04/24/2020
The last day with a visible sunspot was April 4.
Over the past reporting week, April 16-22, average daily solar flux was 69, down a half point from the previous week, when the average was 69.5.
Average daily planetary A index was 7.3 while mid-latitude A index was 7. This was up from 6.1 and 5, mainly due to the first geomagnetic storm of 2020, which pushed planetary A index to 18 on April 19. That event bumped up the average.
Solar flux numbers have been soft of late, with averages over recent weeks of 71.1, 69.4, 70.2, 69.5 and now 69. Lower solar flux probably means less radiation that might excite the ionosphere.
Predicted solar flux is 71 on April 24-30 and 69 on May 1 through June 7. The April 23 forecast shows predicted solar flux at 96 on May 12, but we’ve seen this error once in the past. The digits were transposed. In fact, I won’t even notify NOAA. It will be fun to see how long it takes for anyone to notice.
The predicted planetary A index is forecast at 5 on April 24-29, 8 on April 30, 5 on May 1-4, 12 on May 5, 5 on May 6-16, then 12, 10, 8 and 10 on May 17-20, 5 on May 21-23, then 10, 5, 5 and 8 on May 24-27, 5 on May 28-31, 12 on June 1, and 5 on June 2-7.
Geomagnetic activity forecast for the period April 24-May 19, 2020 from F.K. Janda, OK1HH.
Geomagnetic field will be:
Quiet on: May 1-3, 6, 13-15, 19
Quiet to unsettled on: April 24, 28, 30. May 18
Quiet to active on: (April 25,¨27, May 5, 7-9, 12, 17)
Unsettled to active on: (April 26, 29, May 4, 10-11, 16)
Active to disturbed: nothing expected
Solar wind will intensify on April 17-19, (20,) 26-28, May 4-6, 8-10
- Parenthesis means lower probability of activity enhancement.
- The predictability of changes remains lower as there are no indications.
Frank, W3LPL alerted us to an updated Cycle 25 prediction: "Early this month SWPC published their official updated prediction of Solar Cycle 25 in a new user-interactive graph format. Their updated prediction is based on the results of NOAA's Solar Cycle 25 Prediction Panel. See www.swpc.noaa.gov/products/solar-cycle-progression.
“SWPC forecasts a solar maximum between 105 and 125 with the peak occurring between November 2024 and March 2026. There is broad consensus that Solar Minimum is ongoing this year -- or may have already occurred -- and that Cycle 25 will have no major change in the level of solar activity compared to Cycle 24.
“For many years SWPC's solar cycle predictions have used the Royal Observatory of Belgium's International Sunspot Number. SWPC's official solar cycle prediction now uses the SWPC sunspot number. The International Sunspot Number is typically about one third lower than the SWPC sunspot number.
“While this is SWPC's official Cycle 25 prediction, it’s important to note there is still divergence among various forecasting methods and members of the space weather forecasting community. Most forecasts and forecasters agree that the Cycle 25 peak is likely to be within plus or minus 20 percent of Cycle 24 and is likely to occur between 2024 and 2027. Also see link.springer.com/article/10.1007/s41116-020-0022-z/tables/2.”
N0JK reported from Kansas: "I had sporadic-E on 50 MHz April 21. From 1900-2100z stations in Florida were coming in well. I made about a dozen contacts on FT8. Also decoded CO8LY FL20 calling CQ. Then I saw on the PSKReporter site that two Kansas stations copied HC5VF in Ecuador on 6 Meter FT8 around 2310z. This was likely via multi-hop sporadic-E."
Dr Tamitha Skov, WX6SWW has a new video report: https://www.youtube.com/watch?v=QmfS7P1pJMQ
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 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.
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 16 through 22, 2020 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 68.5, 67.9, 69.8, 68.6, 68.2, 69.1, and 70.7, with a mean of 69. Estimated planetary A indices were 5, 4, 4, 3, 18, 9, and 8, with a mean of 7.3. Middle latitude A index was 5, 4, 4, 2, 16, 8, and 10, with a mean of 7. (arrl.org)
