Propagation News – 29 May 2016

| May 27, 2016

This past week was more settled geomagnetically with the K-index generally staying around zero or one. This was thanks to a lack of solar coronal hole activity and the associated high-speed solar wind streams. The solar flux index declined from the high to mid 90s as large sunspot 2546 rotated out of view. This has left a rather sparse-looking solar disk with only one sunspot group visible. As a result the solar flux index is predicted to remain around 90 in the coming week. NOAA predicts the geomagnetic K-index rising again to an unsettled four on Monday and Tuesday.

Looking further ahead it doesn’t look good for next weekend’s HF CW National Field Day as plasma from a recurring solar coronal hole could push the K-index up to five. This could see the HF bands become noisy and maximum usable frequencies fall away.

Apart from occasional short-skip sporadic-E openings on 10 and 15m, the highest ‘money’ band for Field Day is predicted to be 20m, with 15m perhaps struggling to open to DX. Forty metres may give consistent openings around Europe, with DX being workable at night. Eighty metres may give good openings around Europe after dark, but is unlikely to yield much DX.

VHF and up propagation news

Next week sees high pressure between Iceland and Scotland with low pressure over the near continent. This will mean a north-easterly flow of air from the North Sea. In the summer months, this can lead to extensive mist and sea fog along eastern coasts and give some good tropo conditions from East Anglia to Aberdeen and Lerwick.

This type of tropo depends upon warm moist air blowing off the continent and out across the cool North Sea to give longer DX paths to Denmark, for example. However, with a north-easterly wind it usually means dry cool air gets folded into the mix, and I suspect we may be limited to paths up and down the east coast.

Last week saw some excellent sporadic-E openings on six and four metres. Conditions on Wednesday extended from Scandinavia round to the Balkans and central Mediterranean.

For next week it’s not a good sign that there seem to be few suitably-placed jet streams, often involved with sporadic-E formation. They are mostly located over Spain and the Mediterranean and so a bit too far away.

EME conditions will improve next week with increasing declination and the moon at perigee on Friday.

Category: GB2RS Propagation News