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Propagation News – 4 March 2018

March 2, 2018

As we move into March, HF conditions should be well under way to being more spring-like. As the days gets longer and the nights get shorter, the LF and MF bands can become less attractive and the HF bands can show a little more life for a little longer into the evening. March is also good month for north-south paths such as UK to South Africa and South America.

Last week saw a mixed bag, propagation-wise, with a K-index of 5 on Tuesday the 27th, but there were otherwise calmer geomagnetic conditions later in the week. There were some HF highlights, including TY1TT in Benin being very audible on Tuesday on 20m. There were also some loud east coast US CW stations on 20m near sunset, which bodes well.

NOAA predicts the solar flux index will be in the high 70s next week and geomagnetic conditions will be largely settled due to a predicted lack of coronal hole activity. As this report was being prepared, there were some coronal holes, but only at the solar poles. This means their associated high-speed solar wind may not be Earth-directed. So a solar flux index of 78, settled geomagnetic conditions and equinox-type propagation could throw up one or two surprises on 20, 17 or 15m, hopefully just in time for the Commonwealth Contest on the weekend of the 10th and 11th. But we will have to wait a few more weeks yet before the start of the sporadic E season, so 10m openings may be more elusive.

VHF and up:

Last week saw some good snow scatter propagation on the microwave bands, coinciding—for once—with the SHF UKAC contest. Paths up the eastern side of the UK were particularly good as the snow barrelled in from the continent.

The cold, Siberian blast from the East last week is being displaced by slightly less cold weather from the south. These transitions can often involve strong winds, ruling out any tropo propagation, at least to begin with. Many weather models get us into positive daytime temperatures next week, with a complex pattern of weak lows around Britain. Not exactly ideal for tropo either, even though winds will be lighter. However, with such large amounts of snow on the ground, there will be periods when it’s very misty, and warmer air overlaying the cold snow fields could produce slightly lifted conditions for limited paths.

The long winter wait for the return of Northern hemisphere sporadic E season continues, so the best opportunity for DX on the lower VHF bands still lies in early morning random meteor scatter contacts.

Last week’s lunar perigee and high declination brought good EME conditions, but declination went negative again today and the Moon is heading out to its apogee next Sunday. Get your EME contacts in early this week, as path loses will increase and Moon windows shorten as the week progresses.