SB PROP @ ARL $ARLP029 ARLP029 Propagation de K7RA
ZCZC AP30 QST de W1AW Propagation Forecast Bulletin 29 ARLP029 From Tad Cook, K7RA Seattle, WA July 20, 2012 To all radio amateurs SB PROP ARL ARLP029 ARLP029 Propagation de K7RA
In last week's bulletin ARLP028 we reported a blast of energy from a solar flare headed our way, predicted arrival on Saturday, July 14. The CME hit at 1800 UTC, and had a huge effect on propagation and geomagnetic indices. The next day the planetary A index was 60, mid latitude A index was 39, and the high latitude college A index was 88. Conditions haven't been that upset since March 9, 2012, when the mid-latitude A index was 57, planetary A index was 67, and the college A index was 107.
All other indices were lower, with the weekly average of daily sunspot numbers down over 16 points to 104.7, and average of daily solar flux down 25 points to 141.8.
The latest prediction from NOAA/USAF has solar flux at 95 on July 20-21, 100 on July 22, 105 on July 23-24, 110 on July 25-27 then 165 on July 28 through August 2, 160 on August 3-4, and 165 on August 5.
Predicted planetary A index is 5 on July 20-21, then 12 and 8 on July 22-23, 5 on July 24-27, 20 on July 28-29, 10 on July 30-31, 15 on August 1-2, 10 on August 3-4, 8 on August 5, and 5 on August 6-22.
OK1HH predicts quiet to unsettled conditions July 20, quiet July 21, quiet to active July 22, mostly quiet July 23-24, quiet July 25, quiet to active July 26, active July 27-28, mostly quiet July 29, quiet on July 30, quiet to active July 31 through August 2, quiet August 3, mostly quiet August 4, active August 5, mostly quiet August 6-7, quiet to unsettled August 8, quiet August 9, quiet to unsettled August 10, and active on August 11.
How well do the forecasts from NOAA/USAF (at
http://www.swpc.noaa.gov/ftpmenu/forecasts/45DF.html) do in predicting what will happen next week, or a few weeks out? No statistics here, but I noticed that the current solar flux depression (with flux values at 100 of less for the next few days) has been predicted for weeks. Solar flux values for July 16-19 show the trend, with values of 154.4, 127.5, 109.5, and 100, and now on Thursday July 19 the predicted values for July 20-22 are 95, 95 and 100.
Looking back at the forecast from July 2, we see the same dip around this time of the month, only longer and deeper. That date it showed flux values on July 18-23 at 100, 90, 85, 85, 90 and 100.
On July 9 this was revised, and the dip was only down to 105, centered on July 20-21. On July 13 this was adjusted down, with the minimum at 100, on July 18-20. Revised again on July 14, it now had the flux at 100 on July 19-21. The July 15 forecast shifted it again, at 100 on July 20-23. On July 16 it changed again, with flux values of 105, 95, 95, 95, 95 and 130 on July 19-24. On July 17 the July 24 value changed from 130 to 105, and on July 18 the minimum went from 100, 95, 95, 95 and 100 on July 19-23, and now on July 19 it is 95, 95 and 100 on July 20-22.
So over the past few weeks the forecast for a short term minimum has shifted around the next few days, and we hope it becomes more accurate as we close in on the date.
Dave Greer, N4KZ of Frankfort, Kentucky wrote: "Here it is some 24 hours after total bedlam - a good kind of bedlam - on 6 meters on Monday, July 16. From the DX Sherlock website, I knew before I left work that 6 would be on fire by the time I got home from work. It did not disappoint. In fact, it threw me an unexpected surprise."
"I got on at 2118 UTC and didn't leave the rig for the next three hours as the Caribbean and northern South America boomed into my EM78ne QTH in Frankfort, KY. I worked some 20 stations. None represented new 6 meter DX entities for me but it was still a blast. You don't work Brazil on 6 meters every day, at least I don't."
"But in the midst of the chaos, I heard W3GMT calling CQ with a strong signal and no takers. I felt sorry for him and answered his next CQ. I nearly fell out of my chair when he said his QTH was Charleston, South Carolina. You see, South Carolina was the LAST state I needed for 6 meter WAS. And it only took me 25-plus years to work it."
"South Carolina is practically in my backyard. That's the problem -it's too close. If I had worked at it, I could have worked it years ago but I preferred the casual approach. So 12 years after I worked Alaska on 6 meters, 10 years after I worked Hawaii, I finally got my last state."
"That I didn't expect when I turned on the rig on July 16."
"By the way, I just put up a new 6 meter Yagi on my tower on Saturday so this was the perfect way to break it in. Compared to the big guns on 6 meters - with the KW amps and Yagis with booms that are longer than my tower is tall - I'm just a peanut whistle but with my 100 watts and modest Yagis over the past years I have managed to work 70 countries on 6 meters, all continents and now all 50 states."
"And yes, it is still and will always remain the Magic Band."
Nice report, Dave!
We also got an interesting report from Steve McDonald, VE7SL of Mayne Island, British Columbia. Steve wrote: "As you know from your reports, the 'normal' summer 6m season has been a bit of a disaster here in the PNW as well as many parts of the country. But although the number of openings has been minimal, some of them have been spectacular. You have already reported on the 5 hour opening between the PNW and Europe (June 29) which surely must be an exceptionally rare occurrence as many 40 year plus 6 meter operators have commented that they have never seen anything like it before, myself included."
"This note is to report another example of why 6 meters is called the 'magic band'. Both myself and Johnny, KE7V, (about 40 miles to my southwest in Port Angeles, WA) worked 4Z1UF in Lod, Israel on July 13. Johnny worked him at around 1433Z and I worked him seven minutes later at 1440Z when his signal (as is so often the case with EU propagation) finally drifted far enough north for me to hear him. The distance between us is about 6700 miles. What is remarkable about this contact is that there were really no indicators that the band was open... no beacons from the north (or anywhere else for that matter), no EU video signals coming over the pole and no signals from North America, just 4Z1UF, all alone on the band, calling CQ on CW! Ilya's signal (peaking 569) was in and out here in less than 60 seconds and I believe it was much the same for KE7V."
"Somewhat fortunately, Johnny's beam is difficult to move due to a faulty rotator and he had it temporarily parked towards Europe. He had been casually tuning the band early in the morning, while also watching the Tour de France race on television when he noted and pounced upon the weak signal before it was gone! One wonders how often these very short 'wormhole' openings occur during the height of the summer E season when combined with a very quiet and diminished auroral field in the polar regions! 4Z1UF reported no indicators to the west coast as well and his few 'before and after' QSO's were all along the Atlantic seaboard. Magic!"
Thanks, Steve! Check out Steve's Radio Notebook page at
http://members.shaw.ca/ve7sl/.
Thanks to VE3KKL, Gordon Curling of Kars, Ontario for catching the error regarding the June 12 solar flare in the last bulletin. That should be an X1.4 flare, not X.14.
If you would like to make a comment or have a tip for our readers, email the author at, k7ra@arrl.net.
For more information concerning radio propagation, see the ARRL Technical Information Service at
http://arrl.org/propagation-of-rf-signals. For an explanation of the 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. Find more good information and tutorials on propagation at
http://myplace.frontier.com/~k9la/.
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 July 12 through 18 were 132, 112, 120, 134, 89, 87, and 59, with a mean of 104.7. 10.7 cm flux was 165.4, 147.2, 147.9, 140.5, 154.4, 127.5 and 109.5, with a mean of 141.8. Estimated planetary A indices were 11, 3, 17, 60, 31, 14, and 5, with a mean of 20.1. Estimated mid-latitude A indices were 11, 4, 11, 39, 27, 9, and 5, with a mean of 15.1. NNNN /EX
Topic: Propagation (Read 1352 times)