Propagation News – 6 September 2015

This week brought a much-needed break from the effects of the virtually continuous coronal holes on the sun.

This saw the Kp-index come down to a more reasonable one or two most of the time, with a corresponding improvement in HF conditions. As we are now in September we should see a bigger improvement as we head further into the autumn.

The solar flux index remained firmly below 100 and is predicted to stay below 90 until next weekend, when it may rise to 110-115.

The critical frequency over the UK has risen to around 6.4MHz this week, opening up paths with a maximum useable frequency of about 21MHz at times.

Nevertheless, 14 and 18MHz remain the ‘money bands’ for HF DX, but they remain vulnerable to the effects of the high-speed solar wind at times.

Other highlights to look out for this week include greyline openings to the Pacific on 40m and 80m at sunrise. Gary, ZL2IFB and Tony, ZL2AGY have both been spotted on 40m CW around 050UTC. Paths to the west coast of the USA are also improving, especially on 17 and 20m.

Finally, good luck to all those taking part in this weekend’s HF SSB Field Day. Short path HF predictions from G0KYA for the UK can be found at UK short path monthly forecast maps.

VHF and up propagation

This week a long-awaited area of high pressure is going to move in across the British Isles.

The high should last until mid-week, when an Atlantic low is expected to move in towards the north-western parts of the UK with strengthening winds. Tropo propagation is likely to be slightly enhanced due to the high pressure area and the temperature inversions it creates.

Recent wet weather and damp ground will mean some fog overnight and early mornings, this could create the potential for good ducting conditions within the UK and near continent, although these will tend to weaken as the temperature picks up in the mornings.

Stronger winds in the north-west will probably curtail any lift conditions after midweek.

These enhanced conditions will hopefully help the 2m Trophy and Backpackers contests this weekend, and should hang around for the 70cm Activity Contest on Tuesday evening.

Category: GB2RS Propagation News