Propagation News – 14 January 2024

Welcome to the first HF propagation report of 2024—it looks like it will be business as usual!

A massive X5-class solar flare occurred on 31 December 2023. Luckily, this happened at 2155UTC, so didn’t affect the ionosphere over the UK, but it did launch a large coronal mass ejection, which was forecast to possibly hit the Earth on 2 January 2024. It looks like it largely missed us, although low-energy proton levels streaming past Earth continued to rise and were at the minor S1 radiation storm threshold on Wednesday, the 3rd.

Had active region 3536 been directly facing Earth when the flare was observed, a stronger proton event and geomagnetic storm would have been very likely. Only minor HF signal degradation through the polar zones should be expected because of the minor S1 storm. So, it looks like we dodged the bullet again, but this is a warning that there could be more to come.

Otherwise, the solar flux index declined to the 140s over the Christmas period, although it looks like it may increase over the coming week.

NOAA predicts it could be in the range of 150 to 160 next week, with a maximum Kp index of 3 on Monday, the 8th, or Tuesday, the 9th. However, this could soon change if we have another solar flare and subsequent coronal mass ejection, which could see the Kp index rise two days later. So, make the most of HF when the Kp index is low!

Otherwise, the winter period is when the low bands, from 160 to 40m, come into their own. While solar maximum is not the best time for low-band propagation, there will still be plenty of DX to be worked. Generally speaking, winter is a good time for east-west paths on HF too.

Taking a closer look at 40 metres, the band should open for DX in an easterly direction during the late afternoon and towards the south at sunset. Paths during the afternoon may also include west coast USA in mid-winter. Relatively local contacts should be possible during the day, as the critical frequency remains above 7MHz during daylight.

VHF and up

A new year brings a change of weather type and, after some residual rainfall events at the tail end of the previous week, we should be seeing a marked improvement in the weather as high pressure returns fairly generally across the country by this first weekend of January, ending on Sunday, the 7th.

This will remain near, or very close by, for much of the coming week and into the following weekend. It is good news for tropo, initially over the North Sea towards southern Scandinavia and the Baltic region, but will probably change to favour the western side of Britain in the second half of the week. This is nice timing to coincide with the 70cm band RSGB contests during the week on Tuesday, the 9th, and Wednesday, 10 January.

Up until the middle of the month, we should be alert to rare mid-winter sporadic E propagation. With a very contorted jet stream pattern during the whole period, the chances are better than average. This is another piece of good timing for the 50MHz UK Activity Contest on Thursday, the 11th.

We were going through the Quadrantids meteor shower as this report was being written, so this may provide a little boost to meteor scatter into some of the coming week. Rain scatter will be a rapidly diminishing option during the period as high pressure builds next week. The solar conditions continue to produce elevated Kp index events. So, again, check for auroral openings although, generally, aurora is usually better towards the spring.

For EME, this week we see negative Moon declination, falling to a minimum by Wednesday. So, Moon windows will be short and peak Moon elevation will be low. Path losses are also low, but we are still over a week away from perigee, the closest approach of the Moon to the Earth. 144MHz sky noise increases all week culminating in the Sun and Moon being close in the sky on the 11th.

Category: GB2RS Propagation News