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The K7RA Solar Update


No sunspots seen since January 6, so average daily sunspot numbers declined from 7.7 to 0 for the current reporting week, January 10-16. Average daily solar flux dropped from 71.6 to 69.4 over the same period. Average daily planetary A index went from 7.4 to 4.9, and average mid-latitude A index went from 6.1 to 4.

Predicted solar flux for the next 45 days is 70 on January 18-20, 72 on January 21-24, 71 on January 25 through February 1, 70 on February 2-4, 69 on February 5-13, 70 on February 14-15, 71 on February 16-28, and 70 on March 1-3.

Predicted planetary A index is 5 on January 18-22, then 8, 20, 12 and 8 on January 23-26, 5 on January 27-30, then 10, 15, 12 and 8 on January 31 through February 3, 5 on February 4-10, then 12 and 10 on February 11-12, 5 on February 13-19, then 18, 10 and 8 on February 20-22, 5 on February 23-26, then 12, 18, 15, 10 and 5 on February 27 through March 3.

Predicted smoothed sunspot number for January 2019 is 9. This predicted smoothed sunspot number is what you want to use this month with propagation prediction programs such as W6ELprop, rather than daily sunspot numbers. K9LA explains: "Why should we use the smoothed sunspot number (or smoothed solar flux) and not the daily solar flux? To develop the model of the ionosphere for our propagation predictions, solar data was compared to ionosphere data. The best correlation was between the smoothed sunspot number (or smoothed solar flux) and monthly median ionospheric parameters. Thus, the model was designed to take a smoothed solar index. The “monthly median” aspect means that our predictions are statistical in nature."


No geomagnetic forecast from OK1HH again this week, until he resumes his predictions on January 31. But we have a similar prediction from Tomas Bayer of the Institute of Geophysics at the Department of Geomagnetism at Budkov observatory in Prague.

Geomagnetic activity forecast for the period January 18-24, 2019.

Quiet: Jan 18-23

Unsettled: Jan 19-21

Active: Jan 24-25

Minor storm: possible Jan 24

Geomagnetic activity summary:

We expect an active episode at the end of the forecast period, January 24-25. This episode can peak as a minor storm event although it need not exceed local K-index of 4. Nevertheless, a minor storm event is possible. Until this event, we expect at most quiet to unsettled conditions, from Friday, January 18 until Wednesday, January 23, we expect quiet conditions only with an isolated unsettled event.


The latest from Dr. Skov: “I just returned from the American Meteorological Society (AMS) meeting held in Phoenix, Arizona and the air feels electric. Even though the government absences were sorely noted (#WeMissNOAA hashtags were everywhere for example), the meeting was still a buzz of activity.

“Strangely enough, the cancellations caused by the furlough helped the Space Weather Conference, as it brought many terrestrial meteorologists out of their niche looking for interesting talks to see. Between the Parker Solar Probe and the recently declassified military report on the 1972 super solar storm, we had Space Weather stories to tell.  But what stuck out even more than these stories were the set of talks Mike Cook and I did on this Space Weather community. It was all about you and how you have trained us scientists in the art of Space Weather broadcasting.

“Luckily, I've now learned to come to meetings equipped with multiple cameras. If you have taught me anything on this journey, it's that you want to share in it with me-- and over the next few months, I plan to share it all. I will be releasing interviews and chats, interpretations of talks, 360-degree videos, and more. Some highlights will be included in my forecast videos (like the Parker Solar Probe interview included this week). However, much more will be found on Patreon, where I can freely post videos without worrying about time limitations. I can also post extra information, images, and charts that can serve as additional resources. This is such an exciting time!

“In the forecast this week, Space Weather may be settling down, but the excitement surely hasn't as we dive into the promising new era of the Parker Solar Probe. During his cameo, Nour Raouafi, the Project Scientist for the mission, says what the Probe is observing will forever change how we look at the Sun, its corona, and the solar wind. Although the data hasn't been made public yet (in fact, I was prohibited from taking pictures during Nour's talk), what we have seen thus far is simply stunning. It could fundamentally change our entire picture of how Space Weather reaches Earth.”

Here is Dr. Skov’s latest video:


David Moore and Max White, M0VNG passed this along, about a comprehensive model of the life of a solar flare:


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 January 10 through 16, 2019 were 0, 0, 0, 0, 0, 0, and 0, with a mean of 0. 10.7 cm flux was 70.1, 68.1, 69.6, 68.9, 70, 69.5, and 69.7, with a mean of 69.4. Estimated planetary A indices were 4, 7, 3, 3, 6, 5, and 6, with a mean of 4.9. Estimated mid-latitude A indices were 3, 5, 2, 3, 6, 4, and 5, with a mean of 4.