QST de W1AW
Propagation Forecast Bulletin 48Â ARLP048
From Tad Cook, K7RA
Seattle, WAÂ November 30, 2015
To all radio amateurs
ARRL HQ was closed on Thursday and Friday for the ThanksgivingÂ holiday, which delayed this bulletin by several days. This week weÂ return to the normal schedule, with a preview of the propagationÂ bulletin in the ARRL Letter on Thursday, and the full bulletin onÂ Friday.
Solar activity increased during the last reporting week, NovemberÂ 19-25 with average daily sunspot numbers increasing from 43.3 toÂ 62.7, and average daily solar flux rising from 105.5 to 115.2.
Predicted solar flux is 95 on November 30, 100 on December 1, 105 onÂ December 2-3, 110 on December 4-11, 105 on December 12, 100 onÂ December 13-17, 105 on December 18-19 and 110 on December 20-26.Â Solar flux then peaks at 115 on December 27-31.
Predicted planetary A index is 12 on November 30, 25 on December 1,Â 15 on December 2, 8 on December 3-5, then 12, 20 and 18 on DecemberÂ 6-8, then 8, 12, 10 and 8 on December 9-12, 5 on December 13-15, 8Â on December 16, 5 on December 17-21, then 15, 10 and 8 on DecemberÂ 22-24 and 5 on December 25-31.
At 2317 UTC on November 29 the Australian Space Forecast CentreÂ issued a geomagnetic disturbance warning. High speed solar windÂ stream from a coronal hole is expected to cause a minor geomagneticÂ disturbance on December 1 and 2 with a planetary K index of 5Â possible.
OK1MGW expects active to disturbed geomagnetic conditions onÂ November 30 through December 1, quiet to active conditions DecemberÂ 2-5, active to disturbed again on December 6, quiet to activeÂ December 7-8, quiet to unsettled December 9, quiet to activeÂ December 10, quiet to unsettled December 11-12, mostly quietÂ December 13, quiet to active December 14-15, mostly quiet DecemberÂ 16, and quiet on December 17-22.
On November 19 Don Michalski, W9IXG wrote about a common problem:Â lousy propagation on 75 meters affecting regional nets:
“Tad, this may be a broken record to you but what is going on withÂ the lousy band conditions for the past 5 months?Â I’ve never seenÂ such poor propagation on HF, low bands, since I became a Ham inÂ 1957.
“I run the Badger Weather Net every morning on 3984 KHz and 85Â percent of the time the band is just dead from 5-7 AM.Â Zip.Â ItÂ gets a little better from 7 AM Central time.Â At times, the solarÂ numbers seem to be good but that doesn’t make any difference.Â I’veÂ lost confidence in the SFI, A, K index.Â I had thought, wished, theÂ time change would help but not so.Â Your thoughts?”
The problem is related to low solar activity. Often the low sunspotÂ number or solar flux is not high enough to support NVIS (NearÂ Vertical Incidence Skywave) propagation on 75-80 meters.
Ideally stations in the network would be using antennas that beamÂ radiation straight up, and the ionosphere would reflect signalsÂ straight back to everyone else in the region.
Here are some maps you can check to verify this, in real time:
When the ionosphere over your area does not support propagation at 4Â MHz, then you will have this problem on 75-80 meters.
Julio Medina, NP3CW from San Juan, Puerto Rico sent in more reportsÂ of his 6 meter operations.Â He uses a 6 element Cushcraft Yagi up 35 feet, with an IC706 MkII GÂ and IC746Pro. He reports:
“My 6 meter activity on Nov 15, 2015 was: LU7VB 2117 UTC SSB FF51 inÂ Patagonia, LW4DVA 2123 UTC SSB GF05 in Buenos Aires, LU6DLR 2128 UTCÂ SSB GF05 Hector, TY2AC 2148 UTC SSB JJ16 BENIN, new country on 6Â meters for me, TY2AC 2154 UTC CW JJ16 BENIN, new on CW for 6 meters.
“I forgot to tell you that on September 17, 2015 I worked: LU4FPZÂ 2356 UTC CW FF97, PY2EDY 2359 UTC CW GG66.
“SEPT 18, 2015 0003 PY3FJ CW GG40, 0005 UTC PY2KP CW GG66, 0010 UTCÂ BM6GJL TAIWAN CW PL02.Â Probably the first Puerto Rico to TaiwanÂ contact on 6 meters, as told to me by Jose KP4EIT who has more thanÂ 30 years on VHF, UHF and 6 meters DX in Puerto Rico.
“This contact was confirmed with QSL and in LoTW. Is a new countryÂ for me on 6 meter band.
“0015 UTC CX9AU CW GF05, 0017 UTC PY5KC CW GG56, 0027 UTC LU6HFQ CW,Â 2033 UTC HC8/G8OFQ SSB EI49.”
If you would like to make a comment or have a tip for our readers,Â email the author at, firstname.lastname@example.org.
For more information concerning radio propagation, see the ARRLÂ Technical Information Service web page at,Â http://arrl.org/propagation-of-rf-signals. For an explanation of theÂ numbers used in this bulletin, seeÂ http://arrl.org/the-sun-the-earth-the-ionosphere. An archive of pastÂ propagation bulletins is atÂ http://arrl.org/w1aw-bulletins-archive-propagation. More goodÂ information and tutorials on propagation are at http://k9la.us/.
My own archives of the NOAA/USAF daily 45 day forecast for solarÂ flux and planetary A index are in downloadable spreadsheet format atÂ http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5.
Click on “Download this file” to download the archive, and ignoreÂ the security warning about file format. Pop-up blockers may suppressÂ the download.
Monthly propagation charts between four USA regions and twelveÂ overseas locations are at http://arrl.org/propagation.
Instructions for starting or ending email distribution of ARRLÂ bulletins are at http://arrl.org/bulletins.
Sunspot numbers for November 19 through 25 were 51, 52, 59, 76, 77,Â 66, and 58, with a mean of 62.7. 10.7 cm flux was 108.1, 111, 122.2,Â 122.9, 119.7, 113.2, and 109, with a mean of 115.2. EstimatedÂ planetary A indices were 9, 6, 4, 3, 3, 2, and 2, with a mean ofÂ 4.1. Estimated mid-latitude A indices were 6, 6, 3, 3, 2, 1, and 1,Â with a mean of 3.1.