The K7RA Solar Update


Solar indices were down over the past reporting week (December 31, 2015 through January 6, 2016) with average daily sunspot numbers down from 49.6 to 41 and average daily solar flux down from 122.3 to 98.2.

Average daily planetary A index declined from 21.7 to 16.6 and average mid-latitude A index from 12.6 to 10.6.

Predicted solar flux is 105 on January 8-10, 100 on January 11-12, 95 on January 13-14, then 105, 110 and 115 on January 15-17, 120 on January 18-21, then 115, 110, 105 and 110 on January 22-25, 115 on January 26-27, 110 on January 28, and 105 on January 29 through February 3. Solar flux then peaks for the near terms at 115 on February 5-6 and again at 120 on February 14-17.

Predicted planetary A index is 8 on January 8, 5 on January 9-11, 12 on January 12, 8 on January 13, 5 on January 14-20, then 8, 15, 12 and 8 on January 21-24, 5 on January 25-30, 12 on January 31, 8 on February 1, 20 on February 2-3, 12 on February 4, 8 on February 5 and 5 on February 6-16.

Petr Kolman, OK1MGW, predicts the geomagnetic field will be quiet to unsettled on January 8-9, active to disturbed on January 10, quiet to active January 11, quiet to unsettled January 12-14, mostly quiet January 15-17, quiet January 18-19, quiet to unsettled January 20-22, mostly quiet January 23, quiet on January 24-26, quiet to active January 27-28, quiet to unsettled January 29-30, mostly quiet January 31, quiet to active February 1-2, and quiet to unsettled February 3.

Petr is less certain about his forecast over the period January 15-19.

He predicts increased solar wind over January 10-11 and 27-28.

At 2302 UTC on January 4, Australia’s Space Weather Services issued a geomagnetic warning.

“Coronal hole effects are likely to result in periods of active geomagnetic conditions in the Australian region, with minor storm levels at higher latitudes.

Increased geomagnetic activity expected due to coronal hole high speed wind stream from 06-07 January 2016.”

You can subscribe to their various alerts at

Sure enough, as predicted there was increased geomagnetic activity on January 6-7. The mid-latitude A index on those dates was 12 and 11, the planetary A index was 17 and 14 and the College A index (Fairbanks, Alaska) values were 27 and 22.

Popular Science this week has a basic article about sunspots:

There was a geomagnetic storm last week, just in time for New Year’s and Straight Key Night:

Participants in Straight Key Night noted the poor propagation overnight, but said that during New Year’s Day conditions improved. See and select 2016 ARRL Straight Key Night in the drop-down.

WB2AWQ noted that he used a keyboard, which was actually a piece of wood with five telegraph keys attached.

Don’t miss comments from W0AAA about past Straight Key Nights, as well as his page. As usual for Straight Key Night, many stations used various vintage gear and keys.

For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of the numbers used in this bulletin, see An archive of past propagation bulletins is at More good information and tutorials on propagation are at

My own archives of the NOAA/USAF daily 45 day forecast for solar flux and planetary A index are in downloadable spreadsheet format at and .

Click on “Download this file” to download the archive, and ignore the security warning about file format. Pop-up blockers may suppress the download.

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 December 31 through January 6 were 18, 40, 52, 50, 60, 29, and 38, with a mean of 41. 10.7 cm flux was 96.2, 98.4, 100, 101.9, 95.3, 95.2, and 100.2, with a mean of 98.2. Estimated planetary A indices were 43, 27, 10, 7, 5, 7, and 17, with a mean of 16.6. Estimated mid-latitude A indices were 25, 17, 6, 5, 4, 5, and 12, with a mean of 10.6.