Propagation News – 14 July 2019

| July 12, 2019

Last week saw poor geomagnetic conditions on Tuesday and Wednesday, with the Kp index hitting five. This was due to a weak coronal mass ejection followed by the onset of a solar wind stream from a coronal hole. A solar wind speed above 650km/s, coupled with a strongly south-pointing Bz field, led to geomagnetic unrest at higher latitudes.

The net result was poor conditions on HF, with even the Chilton ionosonde failing to show much of an ionospheric return on its plots.

The poor conditions continued on Thursday with 20m looking distinctly lacklustre and only one or two stations audible on the band. Conditions are predicted to recover by the weekend.

Next week NOAA predicts the solar flux will continue to be around 67, with zero sunspots. Geomagnetic conditions are predicted to be settled with a maximum Kp index of two. This means HF conditions may be better next week, although still subject to the summer doldrums.

We have probably seen the best of the sporadic E season, but do keep an eye on 10m for short-skip openings. A long-term view is that we may not see better HF F2-layer conditions until the autumn. On the bright side, Sunday, the 14th, is the last day for the Cricket World Cup special event stations, so make the most of the final activity.

VHF and up

A period of high pressure is crossing the country this weekend, which should have suppressed the heavy showers of recent days in some areas. Thus rain scatter is now replaced by some tropo, for a time at least.

Early next week the weather position gets very uncertain with weather models split. One version brings a low across northern Britain from the Atlantic, which brings a showery cold front south by the end of the week to offer a chance of rain scatter again.

The other model outcome is for low pressure to drift into southern Britain from the continent, leaving pressure higher in the north, but introducing showers to the south. Either way, the end result is that the early week tropo is replaced by the chance of rain scatter again.

As we move into mid-July, sporadic E can become less commonplace, but still produce some good openings when they do materialise. The FT8 factor means there’s plenty of chance for QSOs via this mode if signals are too low for SSB and CW.

Moon declination is at a minimum on Monday and apogee is just a week away so path losses will continue to increase as the week progresses and Moon windows will be very short with the Moon at low elevations.

There are no major meteor showers this week so continue to look for best DX opportunities via random meteors around dawn.

Category: GB2RS Propagation News