At 2311 UTC on June 14 the Australian Space Weather Forecast Centre issued a geomagnetic disturbance warning:
“In the second half of the first UT day (15 June) the solar wind is expected to be influenced by a High Speed Solar Wind Stream. On the second UT day (16 June) the speed can reach 700 km/s. The geomagnetic activity is expected to reach active levels. Isolated minor storm periods are possible on 16 June.
INCREASED GEOMAGNETIC ACTIVITY EXPECTED DUE TO CORONAL HOLE HIGH SPEED WIND STREAM FROM 15-16 JUNE 2017.
GEOMAGNETIC ACTIVITY FORECAST
15 Jun: Unsettled to Active
16 Jun: Active”
Also, an update from Dr. Tamitha Skov: https://youtu.be/z795uEjCxYI
And an older video from Dr. Skov: https://www.youtube.com/watch?v=PYC6hzifWu0
We saw four zero sunspot days over the past week, so the average daily sunspot number declined from 19.3 to 4.9 from the previous seven days.
Average daily solar flux for this reporting week (June 8-14) was 74.4, down from 77.1 the previous seven days. Average daily planetary A index increased from 5.6 to 7.3 and average mid-latitude A index went from 5.6 to 6.9. Yes, that is correct and not a typo; over the previous reporting week (June 1-7), mid-latitude and planetary A index were both 5.6.
Predicted solar flux is 77 on June 16-23, 72 on June 24, 70 on June 25, 75 on June 26 through July 7, 78 on July 8, then 78, 77, 78, 76 and 74 on July 8-12, 72 on July 13-21, 70 on July 22-23, and 75 on July 24-30.
Predicted planetary A index is 25, 12, 10 and 8 on June 16-19, 5 on June 20 thru July 8, then 15, 12, 8, 15, 25 and 15 on July 9-14, 12 on July 15-16, 5 on July 17-30.
On June 14 Spaceweather.com issued a notification titled “A hole in the sun’s atmosphere”. It included a nice magnetic image. Check out: http://bit.ly/2t4LESL
Or go to Spaceweather.com and check for “A Hole in the Sun’s atmosphere” and if you don’t see it, check the Archives in the upper right corner, and set the date to June 14 or 15. The magnetic image is quite nice and very “granular” as techies often say today.
“This is a coronal hole (CH), a region where the sun’s magnetic field peels back and allows solar wind to escape. A fast-moving stream of solar wind from this coronal hole is expected to arrive on June 16th, possibly sparking G1-class geomagnetic storms. High-latitude sky watchers should be alert for auroras, especially in the southern hemisphere where autumn darkness favors visibility.
Forecasters note that this stream is unusually fast with wind speeds as high as 700 km/s. Moreover, it is threaded with “negative polarity” (south-pointing) magnetic fields. Such fields do a good job connecting to Earth’s magnetosphere and energizing geomagnetic storms.”
Jon Jones, N0JK wrote to me on June 14: “There was a nice 6-meter Es opening from Kansas to the Caribbean on June 12. Logged C6ATA and HH2AA until 2300z. I’m also seeing remarkable JT65 contacts spotted such as 9K2GS, VK4MA, VK8MS, E51WL, and SV9CVY to North America on June 13 and 13.”
ARRL Field Day is next weekend, June 24-25. See http://www.arrl.org/field-day for info. The latest forecast for June 23-25 (we include the Friday before Field Day in case of any predicted geomagnetic events on Friday) has changed from last week, with A index at 5 on all three days and solar flux at 77, 72 and 70.
From F.K. Janda, OK1HH of the Czech Propagation Interest Group, a geomagnetic activity forecast for the period June 16-July 11, 2017.
“Geomagnetic field will be:
Quiet on June 20-22, 27, July 1, 4-5, 7
Mostly quiet on June 26, 28, July 6
Quiet to unsettled June 18-19, 26, July 3
Quiet to active on June 17, 25, 29-30, July 2, 8, 11
Active to disturbed on June (16, 23-24,) July (9-10)
“Amplifications of the solar wind from coronal holes are expected on June 16-19 (20, 26-27), July (8,) 9-11.
Parenthesis means lower probability of activity enhancement and/or lower reliability of prediction.”
This weekend is the CW portion of the All Asian DX Contest. See http://www.dxcoffee.com/eng/2017/this-weekend-all-asian-cw-contest-4/ and http://www.dxzone.com/dx32720/all-asian-dx-contest-.html for details.
Scott Avery, WA6LIE of Salinas, California wrote: “The ARRL VHF contest pretty much fair to poor this year from California here in grid CM96.
“Conditions were poor at best, so digital modes prevailed. It was hit and miss on 6 meters JT65 as band up and down a lot!
“I missed about fifty percent due to band conditions. I was trying to encourage the new mode MSK144 for contest and general use, as it is a lot quicker for those short openings I missed working on JT65. I use MSK144 here on 50.280 and we have very regular morning openings to Southern California, Arizona, and New Mexico, among other places.
“Saying that, keep an eye on the digital modes when conditions are poor. My icing on the cake was working Hawaii on JT65 (KC7I, NH6Y and K2GT).”
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 June 8 through 14, 2017 were 12, 0, 0, 0, 0, 11, and 11, with a mean of 4.9. 10.7 cm flux was 74, 73.7, 74.7, 74.3, 75.2, 74.9, and 74.1, with a mean of 74.4. Estimated planetary A indices were 4, 5, 4, 17, 8, 8, and 5, with a mean of 7.3. Estimated mid-latitude A indices were 5, 6, 5, 14, 6, 6, and 6, with a mean of 6.9.