As we move into April 2018 it is time to think about updating the latest smoothed sunspot number if you are using a VOACAP-based propagation prediction program.
There are a number of different methods used to smooth or average sunspot numbers, but VOACAP recommends the adjusted SSN from the Solar Influences Data Centre in Belgium. So we’ll settle for an SSN of eight. This tells us that solar activity is very low and the predicted solar flux index of 68-70 for this week basically says we are likely to continue to have no sunspots at all. But that doesn’t mean we will have no HF propagation. We can expect to see daytime openings up to 18MHz, with occasional openings on 21MHz as well. It is a little too early for the main sporadic E season, so openings on 12 metres and 10 metres will be few and far between, but not impossible. This time of year does favour north-south paths for F2 layer openings on the higher bands so do check 12 and 10 metres.
The good news is that the NOAA longer-term forecast for next week is for quieter geomagnetic conditions. This often involves crystal ball gazing as the Solar Dynamics Observatory cannot see around the edge of the Sun, but quieter geomagnetic conditions, shown by lower K-indices, could spell better conditions on the HF bands.
Eighty metres remains a mainly night time band and 40 metres may provide 24 hour contacts, with longer paths opening up after dark. It might also be a good time to try a new mode such as FT8, which is getting rave reviews for its ability to secure DX contacts with low power and compromise antennas.
VHF and up:
This week is a rather long range tropo forecast due to the Easter break and this week’s GB2RS deadline having been brought forward.
In the run up to Easter, it’s been very unsettled again, so there is little chance of enhanced tropo. There will be periods of wet and windy weather and some risk of snow in the north. This Easter weekend there is a hint of a weak high developing over Scotland, which will transfer east over the North Sea. The end result is that the UK is still under low pressure with rain or April showers and early signs that there may be more significant low developing towards the following weekend with a chance of severe gales. It’s a long way off, but it is a flag to check the forecasts carefully as we get closer. In the odd quieter days beforehand, it may be worth checking those mast guys before the end of the second week.
So what modes are options? You can try rain scatter on the microwave bands from April showers, sporadic E on 10m and 6m, especially on weak signal digital modes at the end of next week as strong jet streams arrive, but sadly no strong signal for tropo.
Moon declination is negative again and at minimum next Saturday. Apogee is only seven days away so losses are high and increasing and moon windows are shortening.
http://rsgb.org/main/blog/news/gb2rs/propagation-news/2018/03/29/propagation-news-1-april-2018/
