Propagation News – 24 November 2024
We’ve had yet another week of relatively calm geomagnetic conditions. The solar flux index has been in the 160s and despite having 14 M-class solar flares over seven days, we haven’t had any coronal mass ejections to contend with.
As a result, the daytime maximum usable frequency, or MUF, over a 3,000km path has been high, reaching more than 35MHz at times.
The MUF declines after sunset, as expected, settling at about 12-13MHz, meaning the only HF band open to DX has been the 10MHz or 30 metre band.
DX this week has included 3D2Y in Rotuma. This Pacific DXpedition has been spotted in Europe, on 20m, 15m and 17m CW, so plenty of choice as to which band you try.
E51SGC in Rarotonga on the Cook Islands has also been spotted across many of the HF bands, but they will be leaving on the 24 November. The good news is that the team of Stan LZ1GC and Ted LZ5QZ are moving on to Tonga as A35GC from the 25 November until the 7 December 2024.
Gerben (PG5M) is active on the Falkland Islands as VP8G and has been spotted on 20m, 15m and 10m CW. He is there until the 25 November so get in quickly!
Next week, NOAA predicts that the SFI may rise to the mid-250s again. Geomagnetic conditions are largely predicted to be good, although do keep an eye on solarham.com for updates.
And don’t forget the CQ Worldwide CW contest this weekend which should bring a lot of DX to the HF bands.
VHF and up
The weather is now in an unsettled phase with areas of low pressure bringing alternating spells of mild wet and windy weather interspersed with colder brighter and breezy showery weather.
This raises a couple of radio-related points; one is that we will see some very strong and potentially damaging winds in some areas, so check daily forecasts and make sure your mast guys are secure; and secondly an absence of any marked high-pressure Tropo weather.
Rain and snow scatter may be worth checking on the GHz bands in such unsettled weather. Meanwhile, meteor scatter is worthy of greater attention as next week’s list of showers includes the small Alpha Monocerotids shower and the tail end of the big Leonids shower.
This introduces another potential nugget of interest in that since it is widely accepted that meteors form the source material for Sporadic-E. Despite being out of season in the traditional sense, the prevalence of stronger jet streams in unsettled weather makes the next week a possible ‘watch period’ for Es.
If you are curious about what these might look like, check out the propquest.co.uk website and look for the near vertical incidence skywave or NVIS tab for Wednesday 20 November 2024.
During the two events in the middle of the day and evening, the critical frequency of the Es layer reached values of nearly 10MHz, which could equate to four-metre propagation on a good day. You will see the Es blog tab upper air charts also show a jet stream of greater than 100 knots.
For EME operators, the Moon has passed peak declination so Moon availability and peak elevation will be falling. Path losses are high and rising towards apogee on Tuesday 26 November. 144MHz sky noise is low all week.
Category: GB2RS Propagation News
