HF News

The last week was a little more disturbed than usual. We had a Kp index that hit 5.33 as an enhanced solar wind stream contributed to active geomagnetic conditions and an interplanetary shockwave that swept past Earth at 05:19hrs UTC on December 17 caused minor (G1) geomagnetic storming.

A far-sided halo CME event also occurred later on December 17 at 16:00hrs UTC although this was not directed towards Earth.

This shows that the Sun is still very active, and we should not be surprised if we experience more solar flares and CMEs.

The solar flux index stayed in the 160s and 170s and we should keep an eye on active region 3927, which is currently turning to be Earth-facing and has already been the source of some C-class solar flares.

Next week NOAA predicts that the solar flux index may rise slightly to be in the 180s. The largest Kp index forecast is two, which probably means that NOAA is unsure about what will actually happen.

We are pleased to report that OF9X is once again on the air from the land of Santa Claus in Lapland. Up to 16 operators will be on Santa Radio from 160m to 6m, using CW, SSB, RTTY and FT4/FT8. They have already been spotted on 20m/30m CW and 12m/17m RTTY, so there is plenty of scope to work them.

According to prediction program Proppy (www.rsgb.org.uk/proppy), paths to Lapland should be open on 14MHz from 0800hrs UTC to 1800hrs UTC. On 28MHz expect them to be open from 09:30hrs to 15:00hrs UTC. 80m and 40m should be mainly open during the hours of darkness.

As always, across the Christmas period, we recommend that you use solar ham.com and propquest.co.uk for real-time updates on the solar and ionospheric conditions.

VHF and up

We end the last week in a colder unsettled period of weather with strong north-westerly winds and spells of rain or showers.

The air is sufficiently cold that some snow is possible over northern hills. This is potentially good news for rain/snow scatter, especially off fast-moving showers down the coastal fringes of the UK.

Although the nearest high remains near to the Azores to begin with, it slowly migrates east to France and, by Christmas, to central Europe. This will bring high pressure and possible Tropo onto Santa’s list from Christmas Eve onwards. Look for patches of misty low cloud or fog for the best conditions.

As usual, check for other modes; meteor scatter and aurora are both worth consideration and, this is a prime time for ‘out of season’ sporadic-E between now and about mid-January.

One of the helpful aspects of looking for winter sporadic-E is that quite often the jet streams are significantly stronger than in the more traditional summer Es season. Jet streams are a good source of turbulence that can eventually propagate up to the E region to make Es.

Jet streams are shown on upper air charts and can be a good geographical guide to Es prospects in the summer and should therefore be similarly consulted for these winter events.

In this case, they tell us that the first half of next week up to Christmas Day is well set up with a northerly jet stream over central Europe and, more importantly, crossing the Alps - so a second mode goes onto Santa’s list.

Check the VHF clusters and foEs (critical frequency Es layer) graphs on www.propquest.co.uk for early signs of activity, particularly for paths to the southeast into Italy and the Balkans.

The Moon starts the weekend with positive declination but goes negative late on Sunday. Path losses are at their highest due to apogee on Christmas Eve. 144MHz sky noise is high until Wednesday including “near eclipse” conditions all day Monday.

That’s it for this year, how about making a New Year’s resolution to try a new propagation mode? Maybe use SSB or CW on VHF now and again and actually put out a CQ call in 2025!