Propagation News – 17 July 2016

| July 15, 2016

We got the HF prediction half right last week. We forecast the unsettled geomagnetic conditions that struck us on Tuesday, but NOAA got the week’s solar flux index prediction totally wrong. Prior to last Friday the sun had been almost completely spotless, but a new crop of sunspots broke out, pumping the SFI from the mid 70s to the high 90s. This was enough to wake up the higher HF bands, with DX being workable at times on 15 and 10 metres during the IARU HF World Championship last weekend.

Looking forward, sunspot 2565 looks well established and should help keep the SFI higher. The US Air Force predicts the SFI will start the week at about 92 and tail off to 77 by Friday. If that is the case HF DX might be more easily workable this weekend and earlier in the week.

Solar flare activity from sunspot 2565 may be possible and could lead to relatively short-lived HF disruptions at times.

Geomagnetic conditions are predicted to be reasonably settled early in the week, with perhaps more unsettled conditions some time between Tuesday to Thursday due to solar coronal hole activity.

Sporadic E activity could also bring short-skip conditions from 20 to 10 metres at times, but more of that later.

VHF and up propagation

July is still in the midst of the sporadic E season so that’s probably the best exotic mode to seek out again during the coming week. Look during late morning and early evening to save wasted effort, while checking beacons and clusters for a heads-up on what’s happening.

The RSGB forum propagation section contains a daily blog on the location of jet streams, which might be instrumental in forming sporadic E. This can give an early indication of prospects and which direction might be best. There’s still a little time before the season ends to get a few more locator squares in the log.

The prospects for tropospheric propagation are a little above average at first with high pressure nearby over southern Britain this weekend, but expect it to decline early in the week. Tropo paths in summer tend to favour sea paths and any paths over land are best overnight until just after dawn, when heating will break down any inversion. Once the high breaks down, the more unsettled weather pattern will give options for some rain scatter on the GHz bands from mid-week onwards.

The moon is at its lowest declination today and losses are high all week, so the Moon will be low in the sky and only visible for a few hours.

Category: GB2RS Propagation News