HF News
As this report is being written we are awaiting the arrival of solar material as a result of three CMEs that erupted off the Sun, which were sparked by three solar flares. These, coupled with a high-speed solar wind stream from an Earth-facing coronal hole, threaten to initiate a geomagnetic storm, possibly some time on Thursday the 4th or Friday the fifth.
A strong G3 geomagnetic storm has been predicted, which could push the Kp index up to six or seven and maximum usable frequencies down, perhaps stretching into the weekend and affecting national field day.
Meanwhile, the solar flux index has crept up, standing at 147 on Thursday the 4th. This has meant that the ionosphere has been playing ball, with lots of reports of DX being worked, either through F-region propagation or Sporadic E. 10 metres has been sounding like 20 metres at times, especially around the FT8 frequency of 28.074 MHz.
DX to be snagged this week includes 5Z4/MM0ZBH (Kenya), 8Q7ML (Maldives), VJ2L (Lord Howe Island), 5H1KB (Tanzania) and 9X5KM (Rwanda).
We are now heading for mid Summer, which means 20m may be open 24hrs a day. In general, F-region MUFs will be lower than in Winter/Spring, but Sporadic E makes up for that with strong signals on the higher HF bands out to 1,500km on a single hop, with occasional multi-hop openings.
Next week NOAA predicts that the SFI will decline, perhaps into the range 120-135. After this recent geomagnetic upset clears, conditions are predicted to stabilise, with the Kp index forecast to be around two for the beginning of the week commencing the 8th.
Unsettled geomagnetic conditions are then forecast for the 11th to the 14th with the potential for the Kp index to hit four to six, with a corresponding drop in the MUF.
VHF and up
The unsettled weather has brought some heavy rain and a few chances of rain scatter for the GHz bands, but it does also tend to limit the chances of Tropo.
However, it is the UK that retains the unsettled weather, whereas the continent is still enjoying relatively higher pressure, so perhaps stations in southern Britain may be able to gain some Tropo advantage on occasion.
Of the other operating modes, there are options for meteor scatter from the Arietids, which peak early this week, and some predict it will be a strong shower this year. Since it’s a daytime meteor shower it can be very useful for Sporadic-E, which makes use of the ionisation they leave behind.
The Kp index has been gently disturbed at times, but not enough to generate any exciting radio aurora, but it has possibly been disturbed enough to subdue the Sporadic-E at times, which depends upon a stable and low Kp index to be most effective.
Sporadic-E itself has provided some reasonable European openings and a few longer multi-hop paths for the digital modes. This unsettled weather produces strong jet streams, for summer, and should continue to be useful for providing the turbulence needed as part of the process for making Es.
The placement of the jet streams may however be confined to the northwestern fringe of Europe and perhaps prompting a focus upon Scandinavia and northern Europe for any resulting Es.
EME now, and after last week’s low declination and apogee, this week sees Moon declination increasing again and path losses falling. The 144 MHz sky temperature is low all week.