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[Propagation] NW7US Propagation Bulletin 29-X-2004 : CQ WW SSB

To: propagation <propagation@contesting.com>,CQ_Contesting <CQ-Contest@contesting.com>
Subject: [Propagation] NW7US Propagation Bulletin 29-X-2004 : CQ WW SSB
From: "NW7US, Tomas" <nw7us@hfradio.org>
Date: Fri, 29 Oct 2004 08:18:32 -0700
List-post: <mailto:propagation@contesting.com>

This is the last update before the start of the CQ WW SSB contest of 2004. With the contest starting at the start of 30 October 2004 UTC, and running through the end of 31 October 2004 UTC, we are seeing the minor influence of a southern-hemisphere solar coronal hole. This has elevated the solar wind speed to a level just short of 400 km/s. The Interplanetary Magnetic Field's orientation, as measured by the Bz (B subscript z) component, has been negative now for a period of time, enough to increase the geomagnetic activity. We will see the geomagnetic field staying between disturbed and active.

Sometime late on October 31, a very weak coronal mass ejection might arrive, adding to the disturbance of the geomagnetic field. This is a very slow moving CME, so we expect it to arrive later in the day, and maybe even after the end of the contest.

The expected 10.7-cm flux for both days is about 120 to 125. There are a number of sunspot groups visible. My Last Minute Forecast ( http://hfradio.org/lastminute_propagation.html ) prediction still holds Above Normal to High Normal conditions.

The highest bands, like 10 and 15, will suffer the most during the day, due to the geomagnetic influence which will cause a slight depression from the expected ionospheric strength. During the night hours, the critical frequencies will be depressed by as much as 10%. Will this cause this year's contest to suffer?

Based on the last few years contest experiences, I feel that this year could give excellent results. Since each of the previous contest years had geomagnetic activity, sometimes much higher than what we expect this year, and we also suffered the multitudes of back-to-back flares, this will be a tame year of adverse conditions. With a generally more quiet geomagnetic environment, and reasonably high solar energy levels as shown in the 10.7-cm flux readings, we can expect great conditions that might rival last year's.

It will be an exciting weekend. I look forward to seeing the results. Good luck to everyone!


73 de Tomas, NW7US (AAR0JA/AAA0WA)

: Propagation Editor for CQ, CQ VHF, and Popular Communications :
: Creator of live propagation center - http://prop.hfradio.org/ :
: Member, US Army Miltary Affiliate Radio Service (MARS) AAR0JA :
: 122.93W 47.67N / Brinnon, Washington USA - CN87 - CW/SSB/DIGI :
: Website, software, database design - http://newwebmakers.com/ :
: Washington State Army MARS, State Army MARS Director - AAA0WA :
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