RSGB
GB2RS News Team
January 31, 2025
Last week was pretty unremarkable as far as the Sun goes, but it looks like that is about to change.
The seven days preceding Thursday 30 January were characterised by reasonably settled geomagnetic conditions, with a maximum Kp index of 3.67 and a solar flux index that fell from 205 on the 24 January, to the 170s by the 30 January. During this period there had been only four M-class solar flares and no X-class events.
Over the next few days, things could change. Two large coronal holes near the Sun’s equator threaten to upset the quiet conditions. As the solar material flows out it could cause the Kp index to rise, perhaps to 4, with reduced maximum usual frequencies and noisy conditions. But this will depend upon its associated Bz or interplanetary magnetic field.
If it is south-pointing it will couple more easily with the Earth’s magnetic field, allowing plasma to flow in, and the Kp index will rise. However, if it is north-pointing we may see very little effect at all.
So, keep an eye on Solarham.com for real-time updates and look for increased solar wind speed as the main indicator of the approaching solar material. If the Bz does point south we may expect unsettled conditions and possible aurora today, the 2 February.
Meanwhile, three sunspot groups are rotating into an Earth-facing position in the Northern Hemisphere on the Eastern side of the Sun. We have already seen an M-class flare from one of them.
These could boost the solar flux index but could also be a source of solar flares and coronal mass ejections over the coming week.
Strangely, NOAA does not seem to think they will, as its predicted solar flux index over the next seven days is in the 150 to 160s range. It does agree with our prediction of unsettled geomagnetic conditions, although with a projected Kp index of 5 today, the 2 February, falling to 4 over the next three days.
We will just have to wait and see.
Meanwhile, maximum useable frequencies over a 3,000km path are still exceeding 28MHz from around 0830 to 1600UTC. As the month moves on, we can expect the amount of daylight to increase, so this period may be extended.
Make the most of 160 and 80m as the optimum time for these bands has now passed.
VHF and up :
The tail end of the previous week saw a few weak weather features as lows and a front brushed past. However, from this first weekend of February, there will be a trend to higher pressure, which will offer up some tropo opportunities at times during the coming week.
There is a chance of the occasional decaying front drifting down the country but, for most of the next week, it’ll be a tropo story, if anything.
50MHz has been quiet again as we await the return of maybe the last Spring equinox-style propagation of this cycle around mid-March.
Meteor scatter is once again mostly down to random activity although there is one minor shower, the Capricornids-Sagittariids, which peaked yesterday, Saturday the 1st of February.
Rain scatter may be somewhat rarer due to the mainly high-pressure pattern.
Some auroral propagation is not without hope in view of the large coronal hole, which crossed the Sun last week. Keep a lookout for high Kp values, and keep an ear open for watery signals on the LF bands as a good sign of potential activity on the higher bands.
Moon declination goes positive again today, the 2 February. With perigee having passed late yesterday, the 1 February, this means that the upcoming week will be good for EME. This is especially true on the GHz bands, if you have a clear view of the horizon. 144MHz sky noise is low, rising to moderate next weekend.
One final note: there have been some access problems with the data feeds for the Propquest website. Hopefully, these are temporary and have fixed themselves by the time you hear this broadcast. The other data plots such as jet stream charts should continue to update so there is plenty to look at on the other pages.
(Mike Terry/BDXC)
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