Propagation News – 23 April 2017

| April 21, 2017

HF propagation last week was good in parts. There were days when even 20 metres seemed almost devoid of signals, but others when the band really shone. For example, for well-equipped stations 3D2AG on Rotuma Island near Fiji was workable on both CW and RTTY at times on 20 metres. This was remarkable considering the signals go right over the North Pole and geomagnetic conditions were often unsettled.

Solar matter from a coronal hole pushed the K-index up to five on Wednesday, and again up to six on Thursday. This did impact HF and conditions were lacklustre on Thursday morning with all the bands being poor.

Next week, NOAA predicts the solar flux index will be in the mid-80s, thanks mainly to returning sunspot number 2651. This has already been responsible for solar flares and coronal mass ejections and we have no reason to believe this won’t continue. This, coupled with recurring coronal holes, means NOAA predicts very unsettled geomagnetic conditions through to the end of next week, with only next weekend showing some signs of a reprieve.

We don’t really expect maximum usable frequencies to rise much above 14MHz, and even that might be a struggle at times. There is always the chance of pre-auroral enhancements in amongst the mayhem, so keep an eye on HF.

VHF and up

We had a prolonged spell of high pressure over the last week, although not necessarily a major tropo event. There were some modest enhancements at times, so it is worth checking the VHF and UHF bands nonetheless.

This coming week is looking broadly similar on the charts, but there are signs that with the main high being displaced to the west of the UK for much of the time, many parts will be under the influence of a cool northerly flow from around Tuesday on. This could mean that the bulk of the week is more notable for some April shower activity, wintry in the north, but with a risk of some hail or thunder in eastern areas.

So, it feels like there will be the opportunity for rain scatter on the gigahertz bands rather than a week of tropo openings.

But wait, there is more!

We are getting very close to the start of the sporadic E season, and a check of the beacon bands on 10m and 6m could pay dividends, especially in the late morning and late afternoon/early evening.

This week sees the new moon on the 26th and Moon perigee, or closest approach, on the 27th. Path degradation will be low and the Moon will be relatively high in the sky from the UK. This may be a good opportunity to give EME a try even with a relatively small system. However, it is a mainly daytime pass so many people will be at work.

The Lyrids meteor shower activity should have peaked on the night of the 22nd, so we will now see a gradual reduction in rates through the 25th.

Category: GB2RS Propagation News