HF News
Last week was characterised by geomagnetic disturbances, due to high-speed solar wind streams from coronal holes, and a slightly increasing solar flux index.
The Kp index hit five on the 18th and 19th, reducing MUFs and generally being detrimental to HF propagation.
We also had more than 50 C-class solar flares and one M-class event this past week, so nothing too severe. But it was coronal holes that did the damage with two large areas on the Sun. A coronal hole is an area of the Sun with open magnetic field lines that allows solar plasma to escape.
HF conditions were relatively poor during International Lighthouse and Lightship Weekend on Sunday the 16th, with little DX and heavy QSB or fading. The MUF struggled to get to 21MHz and most activity was on 40 metres and 20 metres. Some transatlantic signals were logged, but they were weak and watery. That didn’t stop people from enjoying the event though!
DX to be worked this week includes 3B8/SQ9UM (Mauritius), RI8KR (RRA Island Hoppers on AS-109), RI1FJL (Franz Josef Land), V47JA (St Kitts) and V51WH and V55Y (Namibia).
Good news this week as Propquest is back online, showing near real-time MUFs over various distances. Jim G3YLA says this is a temporary fix pending further work.
NOAA predicts that we will see a solar flux index around 100-120 next week, with relatively poor geomagnetic conditions forecast for this weekend. The Kp index is predicted to be four on the 21st and 22nd, although it then calms down again and should revert to two for the rest of the week.
At the time of writing there are no coronal holes threatening HF propagation, but keep an eye on solarham.com for updates.
We are still analysing the eclipse experiment data, but a video of the 80m WSPR contacts has been produced and can be found at: https://tinyurl.com/80mWS
VHF and up
The return of unsettled weather last week pauses over this weekend as a new high moves across the country from the Atlantic. This gives a good chance for some Tropo and, if the land temperatures pick up again and drift offshore, it could produce some good conditions across sea paths like the North and Irish Seas.
Before mid-week, probably during Tuesday, low pressure will return and push a frontal system across the country followed by further fronts and showery periods for the rest of the week. This could be very good for rain scatter on the GHz bands, especially if the showers turn thundery.
Meteor scatter is still a mix of random and the final trailing off from the Perseids, which finally ends this Monday August 24th and the Delta Aquarids that come to an end the day before. So it’s largely random activity for most of the coming week.
The solar conditions are worth monitoring after recent activity saw the Kp index reach Kp=5 on Tuesday and Wednesday last week. Ideally, we require something a little higher to start considering auroral propagation from southern UK.
Sporadic-E can last into the first week of September, but tends to become harder to find and shorter in duration. No reason to stop checking though; anytime from mid-morning to late afternoon should cover it.
For EME operators, The Moon is at apogee and at minimum declination on Saturday the 22nd so with minimum peak elevation and maximum path losses, it’s a good excuse to check out the mechanics of the antenna. 144 MHz sky noise is very high over the weekend of the 22nd, falling back to low as the week progresses.