Propagation News – 3 December 2023

We were lucky last week – the solar flux index remained quite high and, after the geomagnetic upsets around the 25 November, we had settled conditions, with the Kp index below two.

Unfortunately, it looks like that is all about to change.

On Tuesday 28 November, two M-class solar flares and associated coronal mass ejections caused a plasma cloud to be directed towards Earth. It is expected to catch up with an earlier coronal mass ejection, or perhaps arrive shortly thereafter.

Moderate G2 storming with a chance for strong G3 storming can therefore be expected, with an increased Kp index.

If this wasn’t bad enough, a very large coronal hole is rotating into an Earth-facing position as well.

This became geo-effective on the 2 December, and we can therefore expect any associated plasma in the solar wind early next week. Just how bad it will be is hard to say as it will largely depend on the interplanetary magnetic field of the plasma coming off the Sun. If it’s north facing we might just dodge the bullet but, if it is south facing, we can expect significant auroral displays and propagation to match.

Either way, it will be worth keeping an eye on solarham.net and also the upper HF bands for signs of auroral-type activity. After an initial surge in the MUF we can expect band conditions to decline for at least a day or two.

So, all in all then, we can expect the bands to be disrupted at the end of this weekend ending the 3 December.

Next week NOAA predicts the worst will be over by the 8 December, but we are in uncharted territory and can expect anything to happen. So, work the HF DX if and when you hear it!

On a side note, we are now heading towards winter propagation conditions so expect to hear DX activity on Top Band and 80m at night and especially around sunrise. The 40m band may also throw up some surprises during late afternoon.

VHF and up

The weak-but-cold easterly pattern is providing some sharp frosts, and scattered showers suggest that Tropo is not likely. However, the overnight cooling temperature inversion inland, or anywhere away from the east coast, could see temporary Tropo develop overnight and up to about mid-morning. The showers themselves are mostly fairly shallow and don’t look wonderful from a rain scatter perspective.

All of this changes by mid-week as low pressure starts to dominate again and really takes control for the rest of the coming week. This will bring stronger winds, spells of heavy rain and a return to milder air again. It does not, however, encourage thoughts of Tropo becoming a big player next week!

Don’t forget to check in the early mornings for random meteor scatter opportunities and keep an eye on the Kp index for possible aurora. This is the better option with such an active Sun at the moment and, as we said earlier in the HF report, seems to be a strong player as we finish this first weekend of December.

For EME operators, Moon declination is positive and falling, going negative on Thursday 7 December. Monday 4 December is apogee when the Moon is furthest away so expect path losses to be at their highest. 144MHz sky noise is low all week.

Category: GB2RS Propagation News