QST de W1AW
Propagation Forecast Bulletin 48 ARLP048
From Tad Cook, K7RA
Seattle, WA November 30, 2015
To all radio amateurs
ARRL HQ was closed on Thursday and Friday for the Thanksgiving holiday, which delayed this bulletin by several days. This week we return to the normal schedule, with a preview of the propagation bulletin in the ARRL Letter on Thursday, and the full bulletin on Friday.
Solar activity increased during the last reporting week, November 19-25 with average daily sunspot numbers increasing from 43.3 to 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 on December 2-3, 110 on December 4-11, 105 on December 12, 100 on December 13-17, 105 on December 18-19 and 110 on December 20-26. Solar flux then peaks at 115 on December 27-31.
Predicted planetary A index is 12 on November 30, 25 on December 1, 15 on December 2, 8 on December 3-5, then 12, 20 and 18 on December 6-8, then 8, 12, 10 and 8 on December 9-12, 5 on December 13-15, 8 on December 16, 5 on December 17-21, then 15, 10 and 8 on December 22-24 and 5 on December 25-31.
At 2317 UTC on November 29 the Australian Space Forecast Centre issued a geomagnetic disturbance warning. High speed solar wind stream from a coronal hole is expected to cause a minor geomagnetic disturbance on December 1 and 2 with a planetary K index of 5 possible.
OK1MGW expects active to disturbed geomagnetic conditions on November 30 through December 1, quiet to active conditions December 2-5, active to disturbed again on December 6, quiet to active December 7-8, quiet to unsettled December 9, quiet to active December 10, quiet to unsettled December 11-12, mostly quiet December 13, quiet to active December 14-15, mostly quiet December 16, and quiet on December 17-22.
On November 19 Don Michalski, W9IXG wrote about a common problem: lousy propagation on 75 meters affecting regional nets:
“Tad, this may be a broken record to you but what is going on with the lousy band conditions for the past 5 months? I’ve never seen such poor propagation on HF, low bands, since I became a Ham in 1957.
“I run the Badger Weather Net every morning on 3984 KHz and 85 percent of the time the band is just dead from 5-7 AM. Zip. It gets a little better from 7 AM Central time. At times, the solar numbers seem to be good but that doesn’t make any difference. I’ve lost confidence in the SFI, A, K index. I had thought, wished, the time change would help but not so. Your thoughts?”
The problem is related to low solar activity. Often the low sunspot number or solar flux is not high enough to support NVIS (Near Vertical Incidence Skywave) propagation on 75-80 meters.
Ideally stations in the network would be using antennas that beam radiation straight up, and the ionosphere would reflect signals 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 4 MHz, then you will have this problem on 75-80 meters.
Julio Medina, NP3CW from San Juan, Puerto Rico sent in more reports of his 6 meter operations. He uses a 6 element Cushcraft Yagi up 35 feet, with an IC706 MkII G and IC746Pro. He reports:
“My 6 meter activity on Nov 15, 2015 was: LU7VB 2117 UTC SSB FF51 in Patagonia, LW4DVA 2123 UTC SSB GF05 in Buenos Aires, LU6DLR 2128 UTC SSB GF05 Hector, TY2AC 2148 UTC SSB JJ16 BENIN, new country on 6 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: LU4FPZ 2356 UTC CW FF97, PY2EDY 2359 UTC CW GG66.
“SEPT 18, 2015 0003 PY3FJ CW GG40, 0005 UTC PY2KP CW GG66, 0010 UTC BM6GJL TAIWAN CW PL02. Probably the first Puerto Rico to Taiwan contact on 6 meters, as told to me by Jose KP4EIT who has more than 30 years on VHF, UHF and 6 meters DX in Puerto Rico.
“This contact was confirmed with QSL and in LoTW. Is a new country for me on 6 meter band.
“0015 UTC CX9AU CW GF05, 0017 UTC PY5KC CW GG56, 0027 UTC LU6HFQ CW, 2033 UTC HC8/G8OFQ SSB EI49.”
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For more information concerning radio propagation, see the ARRL Technical Information Service web page 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. More good information and tutorials on propagation are at http://k9la.us/.
My own archives of the NOAA/USAF daily 45 day forecast for solar flux and planetary A index are in downloadable spreadsheet format at http://bit.ly/1VOqf9B and http://bit.ly/1DcpaC5.
Click on “Download this file” to download the archive, and ignore the security warning about file format. Pop-up blockers may suppress the download.
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 November 19 through 25 were 51, 52, 59, 76, 77, 66, and 58, with a mean of 62.7. 10.7 cm flux was 108.1, 111, 122.2, 122.9, 119.7, 113.2, and 109, with a mean of 115.2. Estimated planetary A indices were 9, 6, 4, 3, 3, 2, and 2, with a mean of 4.1. Estimated mid-latitude A indices were 6, 6, 3, 3, 2, 1, and 1, with a mean of 3.1.