Propagation News – 8 December 2024
We had another week of high solar activity but limited geomagnetic disturbances. This meant that the upper HF bands were playing ball all week.
The Kp index only exceeded four on one occasion, on the 30 November when it hit 4.67, but otherwise it has been low.
And with a solar flux index mainly in the 180s this allowed the upper HF bands to shine. The maximum usable frequency or MUF over a 3,000km path has been consistently over 35MHz during daylight hours.
The MUF over 100km has also been more than 14MHz around midday, making 20 metres almost a local band at times thanks to near vertical incidence skywave signals! If you have worked anyone in the UK on 20 metres let us know.
An approaching active region just off the east limb of the sun was responsible for an M2.3 solar flare on the 4 December, so perhaps increased solar activity is on the horizon.
Next week NOAA predicts the week will start with the solar flux index starting in the 180s, perhaps then increasing to 200 as the week progresses.
An increased geomagnetic disturbance is forecast for the period of the 10 to the 13 December, when the Kp index could increase to four.
If this does come to fruition, we can expect MUFs to drop until the storming has passed. As always keep an eye on Propquest.co.uk for near-real-time MUF figures and solarham.com for Kp indices.
VHF and up
Meteor scatter is top of the list this coming week, with the big Geminids shower lasting throughout the month and peaking on Saturday 14 December.
With a peak zenith hourly rate (ZHR) of 150 it’s one of the most active and reliable of the annual showers. Other lesser meteor streams are also in play, so check the meteor scatter frequencies on 144, 50 and 70MHz where digimodes MSK144 and FSK441 will dominate activity.
We have another period of primarily unsettled weather for the lead into this weekend, with deep lows bringing heavy rain, and perhaps some snow over northern hills.
Watch out for very strong winds with potentially damaging gales in places. By the time many of you hear this on Sunday 8 December, we will be mid-way through the main event but hopefully your antennas have survived.
The better news is that the first half of the week is dominated by high pressure, so this brings a chance to repair antennas and get some Tropo time before a slow drift back to unsettled conditions in the second half of the week.
For other modes, GigaHertz band rain and snow scatter will be worth considering especially over the weekend and again later in the week.
Last Friday afternoon saw another big 50MHz F2 opening to North America, so continue to be vigilant if you’re in the shack after lunch and the Kp index is below two.
The solar conditions mean that there is still a chance of Aurora, although the Sun has been a bit quieter recently. Some days the f0Es trace on Propquest shows that weak Sporadic-E is still occurring.
The Moon’s declination is rising again and going positive on Monday. With falling path losses as we approach perigee on Thursday it’s a good week for EME. 144MHz sky noise is low all week.
Category: GB2RS Propagation News
