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Propagation News – 26 May 2019

Geomagnetic conditions have been much quieter over the last week as the result of reduced coronal hole activity and a lack of coronal mass ejections. The solar surface is now devoid of sunspots, so we are back to settled conditions.

Many listeners are reporting that 20 metres is staying open longer at night. This is to be expected as we move towards summer ionospheric conditions, characterised by lower maximum useable frequencies (MUF) during the day, compared with winter, but sustained MUFs at night. This is due to a mixture of increased D-layer absorption during daylight and a change in the ionospheric chemistry to more molecular, rather than monatomic species, which are harder to ionise. Some long-distance contacts into the USA have been reported even at 2am and we can expect these to continue. Twenty metres may even become a 24 hour DX band by mid-summer.

There is a slight chance of an elevated K-index on Friday, the 24th, or Saturday, the 25th, due to an Earth-facing coronal hole, but otherwise the geomagnetic field is predicted to be quiet. NOAA predicts unsettled conditions on the 28th and 29th when the K-index could rise to three or four. The solar flux index will start at about 68 and is predicted to rise to 74 or 76 by next weekend, presumably due to the return of a sunspot group.

And finally, as mentioned in the main news, the RSGB’s Propagation Studies Committee has launched a new HF prediction tool that uses the ITURHFPROP engine. The tool can create predictions to 28 different locations around the world, based on your particular antenna, mode and power. It joins the VOACAP-based tool launched earlier this year, which can be found via rsgb.org/psc.

VHF and up:

This week we will find a tendency for high pressure to be located to the south-west of the British Isles, with any tropo prospects biased towards southern UK into France across Biscay into Spain perhaps. The bulk of the country is dominated by low pressure to give a showery type of weather and offer some possibility of some rain scatter, since it’s likely at this time of the year to be a case of some showers being heavy and thundery.

Sporadic E is working well this season with some openings reported on most days, often as high as 50MHz and occasionally higher. Obviously not all paths have been accessible from the UK, but some have, and so far this season many of the paths have been associated with jet streams. The coming week suggests some further jet stream activity over northern Europe and Scandinavia, while flows over southern Europe become weaker. Maybe it is time for paths to Scandinavia and the Baltic to come to the fore. It’s always worth remembering to check the clusters and, as an operating principle, try a late morning or early evening check on 10m and 6m beacons for signs of activity.

The Moon is at apogee this Sunday so losses are at their highest, but falling as the week progresses. Declination is rising and goes positive on Thursday so EME conditions will become more favourable towards next weekend. Again there is no significant meteor shower activity this week so in between the sporadic E, keep looking for the early morning random meteor peak on the lower VHF bands.

https://rsgb.org

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