Average daily sunspot numbers dropped from 31.6 to 21.3 last week, and average daily solar flux declined from 78.2 to 73.5. The sunspot number was zero on February 8, but recovered to 15 on February 9, with the appearance of one new sunspot group.

Average planetary A index went from 15.6 to 12.9, and average mid-latitude A index from 11.4 to 9.9.

Predicted solar flux is 74 on February 10-12, 78 on February 13-17, 80 on February 18-19, 82 on February 20-21, 81 and 79 on February 22-23, 77 on February 24-25, 75 on February 26 through March 1, 74 on March 2-3, 73 on March 4, 72 on March 5-9, 75 on March 10-13, then 76, 77 and 78 on March 14-16, 80 on March 17-18, 82 on March 19-20 then 81 and 79 on March 21-22.

Predicted planetary A index is 5 on February 10-13, 10 on February 14, 8 on February 15-18, 5 on February 19-21, then 10, 15, 10 and 10 on February 22-25, then 5, 25 and 30 on February 26-28, then 25, 20, 15 and 12 on March 1-4, 10 on March 5-7, 8 on March 8, 5 on March 9-12, 15 on March 13, 10 on March 14-15, 8 on March 16-17, 5 on March 18-20, and 10 and 12 on March 21-22. The index then jumps to 25 on March 26.

F.K. Janda, OK1HH, sends this geomagnetic activity forecast for the period February 10-March 9, 2017.

“Geomagnetic field will be:

Quiet on February 10-11, 13-14, 21, 23-24, 26, March 8-9

Mostly quiet on February 12, 15, 19, March 7

Quiet to unsettled-sometimes, hardly to be forecasted

Quiet to active on February 17, 20, 22, 25, 27, March 3-6

Active to disturbed on February 16, 18, 28, March 1-2

Amplifications of the solar wind from coronal holes are expected on February 16-21, (22,) 26-27.

Remark:

- Parenthesis means lower probability of activity enhancement.”

Jon Jones, N0JK, of Lawrence, Kansas wrote on February 7, “After a slow December and January, February has come alive with winter season Sporadic-E on 6 meters. The last week has had several 6 meter openings, among the best are February 3/4 and February 7/8.

“On February 7 (February 8, UTC) strong Sporadic-E on 50 MHz from IA, KS, NE and MN to south Texas starting at 2330z Feb. 7. N0LL EM09 logged W5TN (EM00), N5XJ (EM10), N5LNO (EM00) and others. I heard the K5AB/b EM01 50.061 MHz strong near the end of the opening at 0155z February 8.”

For more information concerning radio propagation, see 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 February 2 through 8, 2017 were 40, 39, 22, 22, 15, 11, and 0, with a mean of 21.3. 10.7 cm flux was 75.3, 75.1, 74, 72.6, 72.5, 72.1, and 73.1, with a mean of 73.5. Estimated planetary A indices were 21, 18, 11, 15, 13, 7, and 5, with a mean of 12.9. Estimated mid-latitude A indices were 18, 14, 8, 11, 10, 5, and 3, with a mean of 9.9.