- Amateur Radio (Ham Radio) Community

Call Search

New to Ham Radio?
My Profile

Friends Remembered
Survey Question

DX Cluster Spots

Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement

[Articles Home]  [Add Article]  

Propagation Forecast Bulletin #29 de K7RA:

from W1AW Bulletin via the ARRL on July 19, 2013
View comments about this article!

Propagation Forecast Bulletin #29 de K7RA:

Propagation Forecast Bulletin 29 ARLP029
>From Tad Cook, K7RA
Seattle, WA July 19, 2013
To all radio amateurs

ARLP029 Propagation de K7RA

Unsettled geomagnetic conditions continued this week, punctuated by periods of relative quiet. The most active days were July 14 and 15. The planetary A index was 20 and 25, and the mid-latitude A index was 15 and 33 on those dates. Of course Alaska's College A index was higher, at 58 and 34.

The A index is a daily value, and it is calculated from eight measurements per day (once every three hours) of the K index. The K index is a quasi logarithmic value based on magnetometer readings, so each one-point change represents a large difference. The K index is averaged into the daily A index, a linear scale. This gives a pretty good explanation:

Note the graph labeled "The relationship between K and A."

The planetary A index is based on the planetary K index, which is derived from readings at a network of geomagnetic observatories. The mid-latitude K and A index are from a single magnetometer at Fredericksburg, Virginia, near the intersection of Observatory Road and Magnetic Lane, inside the Fort A.P. Hill Army base, about 8 miles southeast of downtown Fredericksburg, Virginia.

You can sometimes find street names with appropriate references where magnetometers are located, for instance, Geophysical Observatory Road for the magnetometer at Newport, Washington, near 48.27 degrees north, 117.13 degrees west.

Over the past week, the average daily sunspot number declined nearly 33 points to 76.9, while average daily solar flux was down 14 points to 113.9. The average planetary A index barely moved, while the average mid-latitude A index rose two points to 12.9.

But yesterday (Thursday, July 18) the sunspot number jumped to 112, far above the average for the previous seven days.

The latest forecast shows solar flux at 120 on July 19, 125 on July 20 and 21, 120 on July 22 and 23, then 115, 110 and 105 on July 24 to 26, 110 on July 27 and 28, then 120, 125 and 130 on July 29 to 31, 135 on August 1 and 2, then 130, 125, 130 and 135 on August 3 to 6, 140 on August 7 and 8, 135 and 120 on August 9 and 10, 125 on August 11 and 12, 120 on August 13, and 125 again on August 14 to 16. It then declines to a minimum of 100 on August 20 and 21, before rising again.

Predicted planetary A index is 20 on July 19 and 20, 15 and 10 on July 21 and 22, 5 on July 23 to 25, then 30 and 10 on July 25 to 27, 5 on July 28 through August 3, 10 on August 4 and 5, 15 and 8 on August 6 and 7, 5 on August 8 to 12, 10 on August 13, and 15 on August 14 to 17.

Petr Kolman, OK1MGW sends a geomagnetic forecast from the Czech Propagation Interest Group. He says that a growing solar wind "may cause remarkable changes in the magnetosphere and ionosphere on July 19 to 22 and 25 to 28."

He predicts quiet to active geomagnetic conditions on July 19, active to disturbed July 20, quiet to active July 21, quiet to unsettled July 22, quiet July 23 and 24, quiet to unsettled July 25, quiet to active July 26 and 27, quiet to unsettled July 28, quiet July 29 to 31, quiet to unsettled August 1, quiet to active August 2, active to disturbed August 3, quiet August 4, mostly quiet August 5, active to disturbed August 6 and 7, and quiet to unsettled August 8 to 10.

At 2330 UTC on July 17 Australia's IPS Radio and Space Services sent a geomagnetic warning, predicting unsettled to active conditions July 18, active with minor storm periods July 19, and quiet to unsettled conditions July 20.

Just after last week's bulletin ARLP028 was issued, Bruce Smith, AC4G of Taft, Tennessee sent in this report: "Just wanted to report a 6 meter sporadic E opening on the morning of July 12 (finally) into EM65 from 0630 AM to 0830 AM CDT just after sun rise. Signals topped out at approximately S-5 with most QSOs made while receiving stations with S-2 signals. The following EU stations were worked or heard by this station during the time range given: EA1EJ, S57RR, G4RRA, CT1HZE, CT1FFU, CT1DIZ, EA5/G0CSC, CT1FJC, PA2M, and the special event station down in the Florida Keys, K4N (EL84). Glad to have made several EU QSOs on 6 meters for the first time this year with my moderate setup using a 5 element Yagi and 100 watts. Still looking for Africa, Asia, and the Pacific."

Keith Reedy, WA9DRO of Terre Haute, Indiana reports from last week, "One of my favorite bands is 12 meters. Not much joy on that band lately, just a few openings from time to time state side. However I did hear an Israeli station on 24.964 MHz last Monday evening July 8 at about 8 PM local time. I am using a 3 element beam at about 35 feet. What does this mean, don't know, but, I hope more of the same."

David Moore sent a link to this Los Angeles Times article about the current weak solar cycle:,0,6978639.story

The article presents an interesting observation about weak solar cycles in the early part of any century. Note they corrected a typo in the original article which confused astrology with astronomy. Oh my!

Elwood Downey, WB0OEW of Tucson, Arizona sent a similar article, about the weak peak:

Pat Hamel, W5THT of Long Beach, Mississippi wrote on July 15, in an email titled "Frustrating propagation modes", "The red lines on the maps show it was a super weekend for part of the country on six meters. I have spent part of today (until they packed up), Saturday, and Sunday listening on the K4N six-meter announced frequencies. I am too close to them. I kept getting what sounded like meteor pings.

This is one of the benefits (?) of living in the middle of the Gulf Coast. If the weather would have been foggy all the way across the gulf, I would have had a pipeline."

Perhaps he was referring to maps here:

Or here:

Jeff Hartley, N8II of Shepherdstown, West Virginia wrote on July 15: "E-skip has been down this year compared to normal, but at least the 6 meter Es openings are a bit more frequent with several multi-hop to the west and one to EU/Northern Africa along with another to EA8 only. 15 and 17 seem down quite a bit from June. It has been tough to work the county hunter mobiles on 17 quite often out in the upper Midwest and Montana/Wyoming/Colorado.

The IARU contest was about as expected with some fun to be had from big PVRC stations operating as NU1AW/3 (IARU HQ) and W1AW/4. I was at NU1AW/3 from N3HBX (signing the /3 was a pain over hundreds of times). But, it was a lot of fun being a multiplier for everyone. 40 opened fairly early to EU with some very strong signals from the big guns in EU and the little guys in the QRN. Northern Europe was weak and watery for the most part but we did log about 4 Asiatic Russians on the west edge in zone 30.

75 phone was pretty good to Europe with rather poor activity. The HQ stations from Chile and Argentina called in with decent signals. There was enough North American activity to keep us fairly busy thru 0500Z and the Yagi fixed at 300 degrees helped a lot with zone 6. Only one zone 2 (VE6) and one zone 3 (VE4) called in along with VA3RAC and several VE2's and 3's. Most signals were loud enough to be heard easily through the constant S9+ QRN.

20 was the "money band" with very good 1000+ QSO totals from us on phone and the usual 20 meter CW team from DX contests at W3LPL operating 2 interlocked radios picking off QSO's in between CQ's as we were doing as well. We had the usual good 20 meter opening around European Russia sunrise and after 0200-0400Z."

Steve Long, AC6T of Santa Barbara, California notes "As an occasional 6 meter fan, I have noticed this past 2 months that the Midwest, East Coast and even Pacific Northwest have enjoyed terrific multihop ES propagation all over the country. Also, frequent openings to Japan and Europe. I'm puzzled (not to mention disappointed) why my corner of DM04 (Santa Barbara) and Southern California in general have had so few decent openings. 6 meters has been a great white noise source nearly all summer. Even Arizona seems to do better than we do. Any wisdom as to why this might be?"

I have NO idea. Happenstance?

Maybe the activity during the CQ Worldwide VHF Contest this weekend will change the 6 meter fortunes of Southern California. See for more information.

For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of the 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

Sunspot numbers for July 11 through 17 were 85, 87, 66, 88, 77, 61, and 74, with a mean of 76.9. 10.7 cm flux was 113.4, 117.6, 114, 112.9, 114.1, 113.9, and 111.3, with a mean of 113.9. Estimated planetary A indices were 18, 9, 10, 20, 25, 5, and 5, with a mean of 13.1. Estimated mid-latitude A indices were 15, 9, 8, 15, 33, 5, and 5, with a mean of 12.9.

Source: W1AW Bulletin via the ARRL.

Member Comments:
This article has expired. No more comments may be added.
Propagation Forecast Bulletin #29 de K7RA:  
by AE6RO on July 21, 2013 Mail this to a friend!
The amount of deafening apathy about the Sun's weak cycle amazes me. People can't look up long enough from their stupid "smart" phones to pay attention to what is happening in the sky.

Wise up, people! John
Email Subscription
You are not subscribed to discussions on this article.

My Subscriptions
Subscriptions Help

Other News Articles
IARU Watching Wireless Charging Technology:
What Do Solar Indices Mean?
When All Else Fails, Amateur (Ham) Radio Works:
Manager Reopens Jefferson City RadioShack:
Martin F. Jue Joins Amateur Radio Roundtable: