Propagation News – 12 January 2025
First, let’s take a look at last week’s solar activity. As predicted, the solar flux index declined to the 160s. We had one X-class solar flare on the 4 January and there have been 11 M-class flares since then. The net result was that the ionosphere was unsettled from the 4 to the 6 January with the Kp index hitting 5 on the 4 January. Following this, the Kp index was at 4 on the 5 and 6 January.
There were reports of visible aurora over the UK on Saturday the 4 January, but it was nothing like the record-breaking aurora in April 2024.
There were coronal mass ejections, or CMEs, over this period but they were mainly facing away from Earth. Maximum usable frequencies, or MUFs for short, held up over this period, although the shorter days meant that the MUF over a 3,000km path didn’t stay above 28MHz for long after sunset. MUFs plummeted to below 10MHz by 1800UTC on Sunday the 5 January.
The message is clear – get your high-band DXing done by sunset!
Next week it looks like the Sun is going into hibernation. The main sunspots will be disappearing over the western limb, leaving it looking a little bare. As a result, NOAA predicts that the solar flux index will remain low until the 16 January when it is predicted to climb into the 200s once again.
Unsettled geomagnetic conditions are forecast from the 16 to the 20 January with a predicted maximum Kp index of 4. There are currently no coronal holes to worry about.
So, in conclusion, this weekend ending the 12 January looks set to be reasonable for HF operating, barring any X-class solar flares and accompanying CMEs. We predict that MUFs over 3,000km will be above 28MHz from around 0900UTC to 1500UTC.
VHF and up
We are in the middle of a proper winter cold spell at the moment, and we are about to see a large high coming over the country.
This high is building in cold air and it means sharp frosts and perhaps some fog, so there’s a chance of patchy tropo at times. Conditions may further improve as the high slips south after this weekend ending today the 12 Janaury. This may allow milder, moister Atlantic air in from the west to improve the refractive index contrast across the inversion, which could lead to tropo.
The solar conditions have remained interesting and produced a few aurora alerts, so we can probably benefit from watching the Kp index during the coming week.
Meteor activity has passed its early January peaks, and we are now sliding back into random meteor activity as our best options. These tend to be better just before dawn. There is just one minor shower this week. The Gamma Ursae-Minorids is active from the 10 to the 22 January and peaks on the 18 January.
We have mentioned Sporadic-E quite a lot recently but, with the passing of the meteor activity, the chances of it occurring reduce considerably. Although limited activity may enhance the lower bands, it probably won’t feature in the usual high HF and VHF bands.
The Moon reaches maximum declination this weekend, ending today the 12 January. Moon windows are long and peak Moon elevations are high. Path losses are also high and increasing all week. 144MHz sky noise is low all week.
Category: GB2RS Propagation News
