Propagation Forecast Bulletin – February 23, 2018


Propagation Forecast Bulletin 8  ARLP008
From Tad Cook, K7RA
Seattle, WA  February 23, 2018

To all radio amateurs

Average daily sunspot number dropped from 24 during the previous seven days, to 5.6 in the current reporting week, February 15-21. That average is so low because no sunspots have been seen since February 17, and no new sunspot regions were observed since February Average daily solar flux dropped to 70.1 in the current period from 77.4 in the previous week.

Based on the latest 45-day prediction for solar flux, I expect sunspots to re-appear by March 2 or 3, when solar flux is expected to increase suddenly.

Predicted solar flux is 68 on February 23 to March 1, 69 on March 2, 76 on March 3-12, 74 on March 13-14, 72 on March 15, 70 on March 16-25, 72 and 74 on March 26-27, and 76 on March 28 through April 8.

Predicted planetary A index is 8 on February 23-25, then 12, 16 and 8 on February 26-28, 5 on March 1-3, 8 on March 4, 5 on March 5-13, then 10, 8, 12, 16, 14 and 12 on March 14-19, 8 on March 20-22, 5 on March 23-30, 8 on March 31 and 5 on April 1-8.

Greg Andracke, TI7/W2BEE wrote from Costa Rica, where he is vacationing:

“Now on the air with a 124.5 ft. sloper. Working CW ONLY when not in the pool! In Playa Garza, Guanacaste, Costa Rica until about March If anyone needs a CW contact, email me at, — I’m not running pileups, just chatting with folks. Made only a few contacts during ARRL DX Test because I couldn’t get antenna installed until about 3 hours before the test was over.

“Worked VK3IO on 30M with my modest setup, K2/100 and sloper into 9:1 UNUN.”

Greg has a fascinating career filming documentaries. See .

A new space weather video from Dr. Tamitha Skov from last week: .

Paul Gray, N0JAA of Melbourne, Florida wrote:

“Late Winter/early Spring is generally the time of year in Florida when we typically experience tropospheric ducting.  2018 is no exception.  This year I have experienced a good amount of ducting on 2 meters. I don’t have sideband capability on that band currently, so my experience is limited to FM repeaters and simplex.  For the VHF bands of 2 meters and 1.25 meters, and the UHF 70 centimeter band (and perhaps higher), tropospheric ducting in Florida occurs mostly in the late evening and overnight hours.  The 6 meter band, at least in my personal experience, does not appear to be significantly affected by tropospheric ducting.

“Over the last week or so, I have been receiving a distant repeater on my club’s repeater frequency of 146.610 MHz (W4MLB) in Melbourne. I have been able to receive and, after a fashion carry on QSOs with, several stations on the K4GSO repeater.  The trick is to let each repeater drop before responding, but it can be done.  Considering that 2 meters is basically line of sight +/- a few miles beyond the horizon, and the distance between Melbourne and Ocala is approximately 150 miles, this is a good feat, especially with a 5-watt HT and a 1/2-wave mag mount antenna!  I would consider this DX on 2 meters.

“This is my recent experience with propagation.  It isn’t ionospheric propagation, but tropospheric ducting will produce propagation on a more local scale which is useful in and of itself.”

Geomagnetic activity forecast for the period February 23 to March 20, 2018 by F.K. Janda, OK1HH.

“Geomagnetic field will be: Quiet on February 25-26, March 1, 6, 10, 12-13, 19-20, Mostly quiet on February 27, March 2, 7, 11, Quiet to unsettled on February 23-24, March 3, 5, 8, 15-16, Quiet to active on February 28, March 4, 9, 17-18, Active to disturbed on March 14.

“Amplifications of the solar wind from coronal holes cannot be predicted for the period until March 10, but I do not expect any significant upsurge. Then solar wind will intensify on March 18-20.

“Remark: – Parenthesis means lower probability of activity enhancement. – With regard to ongoing changes, current forecasts remain less reliable, especially in the first half of March.”

Tomas Hood, NW7US who edits the Propagation column in CQ Magazine was interviewed by Eric Guth, 4Z1UG for Eric’s podcast “QSO Today.” .

If you change the end of the above URL from nw7us to k7ra, you’ll hear my interview from about two years ago.

If you would like to make a comment or have a tip for our readers, email the author at, .

For more information concerning radio propagation, see the ARRL Technical Information Service web page 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 February 15-21, 2018 were 15, 12, 12, 0, 0, 0, and 0, with a mean of 5.6. 10.7 cm flux was 72.5, 71.5, 69, 70.3, 69.1, 70.5, and 67.6, with a mean of 70.1. Estimated planetary A indices were 11, 7, 12, 14, 17, 5, and 4, with a mean of 10. Estimated mid-latitude A indices were 6, 7, 10, 14, 11, 3, and 3, with a mean of 7.7.


ARRL is the national association for Amateur Radio in the US. Founded in 1914 by Hiram Percy Maxim as The American Radio Relay League, ARRL is a noncommercial organization of radio amateurs.

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