Propagation News – 12 May 2024

Disrupted solar conditions continued this week with X-class solar flares aplenty.

Four X-class events on the 8 and 9 May prompted coronal mass ejections, which could join together to impact the Earth this weekend. We can expect a strong G3 event with the Kp index rising to 6 and the potential for visible aurora in the UK.

It’s hard to be positive about this as HF conditions this weekend, ending today the 12 May, are likely to be very disrupted with reduced MUFs and noisy bands.

But do look out for auroral signals, perhaps on the 10m band, and above, and a potential HF band enhancement just as the plasma cloud hits.

The solar flux index hit 227 on Thursday 9 May, which is one of the highest we have had in this cycle. But don’t get carried away as it is forecast to decline.

Meanwhile, conditions have been typical for this time of year, with reduced F-layer propagation on the 10m band, offset by the start of the Sporadic-E season. The lower HF bands are staying open later in the evening, and may even increase to all night on the 20m band, as we heard towards June and July.

Next week, NOAA predicts that the solar flux index will drop below 200, but remain at or above 175 all week. After this weekend’s chaotic geomagnetic conditions, we can expect the Kp index to fall to 2, but increase again on the 13 May, to perhaps 4.

In the meantime, solar maximum is still predicted to be later this year, although geomagnetic disturbances are likely to increase on the downward part of the cycle. So, buckle up for a rough ride!

VHF and up

We end the current week with high pressure over the country and some occasional Tropo paths, especially over surrounding waters. The high will decline from the west as we progress through this weekend.

At the time of reading on Sunday, the transition will be all but complete and low pressure will remain in control for much of the coming week. This means periods of rain, heavy showers or thunderstorms and quite windy weather at times. In terms of propagation, a shift to rain scatter is a good choice for those equipped for the GHz bands for the week ahead.

Recent solar activity continues to offer chances of auroras so remember to monitor the Kp index and check for fluttery signals on the HF bands and raspy signals on VHF. The many clusters and band reports should be a good tool for these conditions.

Lastly, the Sporadic-E season is having a few starting twitches. Earlier in the evening of Wednesday 8 May, there was a short opening of about an hour to Scandinavia on 6m CW from a patch in the middle of the North Sea. The positions of the jet streams may not entirely suit further openings in the shorter term but, as the low pressure moves in next week, things could improve for Sporadic-E paths to Iberia and central Mediterranean.

With the Eta Aquariids peak now past, the next big meteor shower isn’t until July with the Delta Aquariids. But before the Delta Aquariids, we can look forward to the Arietiids in late May.

However, the Eta Aquariids will continue to produce the odd ping or burst. Last week there was plenty of evidence of meteors continuing to burn up after the peak. There may still be the odd one during the coming week together with the usual background sporadic meteor returns.

As the Moon starts to decline this week, the distance between the Moon and Earth is also beginning to increase and with it the path loss increases to a maximum on Friday 17 and Saturday 18 May. However, sky noise will remain low all week. The Moon is favourably placed for daytime operating this week.

Category: GB2RS Propagation News