Propagation News – 28 April 2024
We had another week with plenty of sunspots, and HF conditions were quite good in the second half.
Earlier, the Kp index reached 3 and 4, which didn’t help maximum useable frequencies, or MUFs for short. For example, on Sunday the 21st, the Kp index rose to 4 and the MUF over a 3,000km path remained stubbornly below 21MHz until later in the morning.
This could have been due to a coronal hole on the Sun’s equator, which added to the solar wind. By Wednesday, conditions were nearly back to normal, with a Kp index below 2 and an MUF of more than 24MHz. By Thursday the improvement had continued, giving us an MUF of more than 28MHz by 0900UTC.
There have been many reports of 10m band DX being worked, including Sebastien, FK4AX and Pat, FK8HA in New Caledonia in the Pacific on SSB. Sebastien has just got his licence and is keen to work DX from the UK.
This shows that it is worth keeping an eye on the CW and SSB portions of the 10m band, which can often throw up surprises.
Next week, NOAA predicts that the solar flux index will decline to around 160. The Kp index is predicted to be around 2 to 3, but that may be wishful thinking. With 16 active regions visible on the Sun’s surface on Thursday, anything could happen. Only minor C- and M-class flares have occurred recently but, as we always say, it wouldn’t take much for those to turn into X-class events.
So, make the most of quiet geomagnetic conditions when we have them as, by the time you read or hear this, we could once again have very unsettled conditions indeed.
VHF and up
The cold, unsettled weather will ease its grip over the last few days of this week, ending the 28 April, but only because the whole area of low pressure is moving across the country this weekend.
Low pressure remains close by for much of the following week and only a hesitant return of high pressure west of Ireland will improve things for western Britain at the end of the week.
The result is a chance of Tropo for western Britain next week, but it will probably be of limited quality since it is likely to form in cold, dry air across any temperature inversion.
The remaining option in such weather patterns is primarily rain scatter for those on the GHz bands. The many online weather radar displays can be used to highlight the areas of heaviest rain.
We are past the peak of the Lyrids meteor shower, but the Eta-Aquarids, with a Zenithal Hourly Rate of 50, peaks next Sunday 5 May around 2100UTC. Until then, rely upon random activity which tends to be better around dawn.
The Sun has been more active again recently, so monitor the clusters and Kp index for signs of geomagnetic activity and the chance of an aurora if the Kp index exceeds 5.
Sporadic-E tends to produce a few early examples in May ahead of its June peak. Check the DX clusters during late afternoon or early evening as openings can be very brief early in the season. Start on the 10m band and, if short skip within Europe is present, move up to the 6m band. Digital modes are more sensitive so check FT8 reports to give clues as to where the chances are greatest.
For EME operators, the Moon is at minimum declination today, Sunday 28 April, meaning we’ll have short Moon windows to start the coming week. Path losses are falling but perigee, when the Moon is at its closest point, is still over a week away. 144MHz sky noise is high this weekend, ending the 28 April, but falls to low by the end of the coming week.
Category: GB2RS Propagation News
