Each of the weekly solar and geomagnetic indicators that we track were lower this week. Average daily sunspot number dropped 10.6 points to 25.1, and average daily solar flux was 4.5 points lower than the previous week at 76.9.

It is comforting to see though that we have not witnessed a day with zero sunspots since April 17. Average planetary and mid-latitude A index were both 5.6, down from the previous week which had planetary A index at 26.4 and mid-latitude at 18.4.

The A index is expected to remain quiet until May 17-20.

As of Thursday night, May 4 the predicted solar flux is 76 on May 5-8, 74 on May 9-12, 75 on May 13-14, 80 on May 15-18, 85 on May 19-21, 80 on May 22-23, 77 on May 24-27, 75 on May 28-30, 73 on May 31 through June 8, 75 on June 9-10, 80 on June 11-14, 85 on June 15-16, and 88 on June 17.

Predicted planetary A index is 5 and 8 on May 5-6, 5 on May 7—9, then 8, 5, 8, 8, 5, and 8 on May 10-15, then 15, 30 and 25 on May 16-18, then 45, 50, 15, 10 and 8 on May 19-23, then 5 on May 24-27, then 12 and 8 on May 28-29, 5 on May 30 through June 1, 8 on June 2-4, and 5 on June 5-10, then 8, 15, 30, 25, 45 and 50 on June 11-16.

Also related to planetary A index is the OK1HH bulletin from the Czech Propagation Interest Group:

Geomagnetic field will be:
Quiet on May 10, 14-15,
Mostly quiet on May 9, 13, 16, 25-30
Quiet to unsettled May 5-6, 22-24, 31
Quiet to active on May 7-8, 11-12, 19-21
Active to disturbed on May 17-18

Amplifications of the solar wind from coronal holes are expected on May (5-9,) 16-19, (20)

Remark:
- Parenthesis means lower probability of activity enhancement and/or lower reliability of prediction.

Remember, you can get a new and revised 45-day forecast for solar flux and planetary A index daily, usually after 2100 UTC from NOAA at ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ .


Dr. Skov released a new space weather video commentary yesterday: http://bit.ly/2pdyRv7


Bob Kile, W7RH, of Las Vegas, Nevada noticed a nice sporadic-E six meter opening on May 3: “Spring is here and so was the first Sporadic E propagation on 6 meters for the season. There were openings from the southwest to mid-west on May 2 and 3. I happened to be listening on May 3 when the band opened at about 00:00 UTC to the mid-west. Beacons were copied in Colorado, Oklahoma, Texas and Kansas. I could not hear the guys in California but a few in southern Arizona could be heard at times.

“Stations worked were in West Texas, Wyoming, Idaho and Colorado. Of special note, two stations in Cheyenne, Wyoming, WY7HR and WY7KY, were solid copy for several hours when the band finally closed about 0200 UTC.”

Bob is using a 3-element Yagi antenna on for 6 meters mounted low on his patio. But I think more interesting is his HF remote base station literally in the middle of nowhere in the Northern Arizona desert, a good distance northeast of Seligman, and approximately 240 miles from Bob’s home in Las Vegas. You can check his QRZ.com listing or http://w7rh.net/ for a deeper rundown.


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 April 27 through May 3, 2017 were 23, 35, 34, 33, 11, 25, and 15, with a mean of 25.1. 10.7 cm flux was 78.2, 78, 77, 77.4, 75.3, 77.2, and 74.9, with a mean of 76.9. Estimated planetary A indices were 7, 6, 6, 6, 5, 5, and 4, with a mean of 5.6. Estimated mid-latitude A indices were 10, 6, 6, 6, 5, 4, and 2, with a mean of 5.6.