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The K7RA Solar Update


At 0326 UTC on October 12 the Australian Space Forecast Centre issued a Geomagnetic Disturbance Warning.

”The high-speed streams associated with a recurrent positive polarity Northern hemisphere coronal hole are expected to persist for a few days. If the Bz component of the IMF turned strongly southward for prolonged periods, earth could experience Minor Storm conditions on 13 October.

“Increased geomagnetic activity expected due to a coronal hole high speed wind stream for 13 October 2017.”

Earlier reported, “A hole in the sun's atmosphere is spewing solar wind toward Earth, and this is sparking bright auroras around the poles on Oct. 11. At the time of this alert, a G1-class geomagnetic storm is underway. NOAA forecasters estimate a 70 percent chance of continued storms at high latitudes on Oct. 12 and 13 as Earth moves deeper into the solar wind stream. Visit for pictures and updated forecasts.”

There were no sunspots visible on October 8 through 12, and the last new sunspot to appear was September 25, which was still visible on October 7, but not since then.

Average daily sunspot numbers for the past week (October 5-11) dropped from 32.6 the previous seven days to 8.4. Average daily solar flux declined from 87.9 to 76.8. Geomagnetic activity also dropped but is now increasing. Average daily planetary A index went from 16.3 to 8.9, and average mid-latitude A index went from 12.7 to 8.

Predicted solar flux is 70 on October 13-17, then 72 on October 18-19, 80 on October 20-31, 76 on November 1-5, 74 on November 6-14, 76 on November 15, and 80 on November 16-26.

Predicted planetary A index is 35, 25, 20, 10, and 8  on October 13-17, 12 on October 18-19, 5 on October 20-23, then 35 and 45 on October 24-25, 15 on October 26-27, then 10 and 8 on October 28-29, 5 on October 30-31, then 8 and 10 on November 1-2, 5 on November 3-5, then 8, 25, 30, 36, 28, 16 and 8 on November 6-12, 5 on November 13-19, then 35 and 45 on November 20-21, 15 on November 22-23, then 10, 8 and 5 on November 24-26.

Geomagnetic activity forecast for the period October 13 till November 8, 2017 from F.K. Janda, OK1HH.

"Geomagnetic field will be:
Quiet on October and November-irregularly
Mostly quiet on October and November-irregularly
Quiet to unsettled October (18-22, 24,) 28-29, (30-31,) November (1-2, 4-6)
Quiet to active on October 13-16, (17, 23,) 26-27, November 3, 7
Active to disturbed on October 25, November 8

Amplifications of the solar wind, mostly from coronal holes, are expected on October 12-17, (18, 22, 24,) 25-26, November 7-12

- Amplifications of the solar wind-prediction is less reliable at present.
- Parenthesis means lower probability of activity enhancement and/or lower reliability of prediction.

Here is a new video from Tamitha Skov, Space Weather Woman:

I understand Dr. Skov is studying for her amateur radio exam!

Here is a report from N8II in West Virginia, sent on October 9: “There were quite decent conditions over the weekend; OH0Z on Aland Island was S9 on 15-meter SSB both Saturday and Sunday. Despite a flux of 72 today, I heard northern Sweden on 15-meter CW and worked several Ukraine stations with good signals in the 1400Z hour along with others farther west in Czech Republic, Bulgaria, Germany, England, Spain and France. Fifteen meters has been open well to EU almost every day in the past 2 weeks! I worked the California QSO party and found that 20 meters was excellent well into the evening Saturday (open past 0045Z). Fifteen meters was very good into California from 1600-2000Z Saturday with southern California noticeably favored on Sunday until around 1900Z. Starting at 2007Z, I worked 6 southern California stations on 10-meter CW, all of which were less than S9, some weak. N4PN in Macon, Georgia reported over 100 CA QSOs on 10 meters in the party!”

On October 6, Bil Paul, KD6JUI of Dixon, California sent this: "After having had a rough time over the past several months getting out on HF from my kayak with just 10 W, yesterday (October 5) I was operating on 17 and 20-meter SSB while on the water and easily got out using my end-fed half-wave wire vertical (cut for 20 meters). I worked as far as the East Coast without much difficulty. I even had an XE2 from lower Baja California break into a QSO to tell me I was 5/9 down there. The solar flux was 85 – enough to make quite a difference."

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 October 5 through 11, 2017 were 26, 22, 11, 0, 0, 0, and 0, with a mean of 8.4. 10.7 cm flux was 84.7, 84.1, 79.6, 76.7, 72.3, 70.9, and 69.6, with a mean of 76.8. Estimated planetary A indices were 7, 9, 5, 4, 3, 4, and 30, with a mean of 8.9. Estimated mid-latitude A indices were 6, 6, 5, 3, 2, 13, and 21, with a mean of 8.