HF Propagation News
The 2026 solar eclipse is done and dusted so we can get back to normal HF propagation predictions!
The Solar Flux Index dropped below 100 this week, which is more symbolic than anything. But it does show where we are heading as Solar Cycle 25 drops away.
The SFI was 99 on Thursday 13th with five sunspot groups visible on the solar surface. Activity has been settled with only 12 minor C-Class solar flares over the past seven days. The Kp index has remained low over the past few days, with just one excursion to 5.33 on August 8th, thanks to an incoming solar wind stream from a coronal mass ejection. Otherwise it has been mainly in the ones and twos which bodes well for HF.
Sporadic E effects are still showing up on HF, while we haven’t yet seen the first signs of an autumnal change in conditions. A plot from the Dourbes Digisonde shows the MUF over a 3,000km path only got as high as 16.8MHz at noon on the 12th. There were excursions up to 21.5Mhz later in the day, but this suggests that 15 and 17m are opening now and again, so keep an eye on the bands. It may sound quiet, but they may open up at any time.
DX to be worked this week includes A50QO (Bhutan), 3B9/SQ9UM (Rodrigues Island), J68TT (St Lucia), C6AUB (Bahamas) from the 19th, OJ0JR and OJ0YL (Market Reef) and RI1FJL (Franz Josef Land).
Next week NOAA predicts that the SFI may remain around the 100-115 mark.
We may have unsettled geomagnetic conditions around the 17th-19th, with a predicted maximum Kp of five. More settled conditions are forecast for August 20th onwards with a maximum Kp of two. So it looks like later next week and next weekend will be best for HF DX.
VHF and up propagation news
The long spell of settled weather for most southern parts of the country may get a shake up during next week as the high pressure to the east of the country weakens to allow low pressure to move in, bringing some much-needed rain.
Now, northwestern parts of the UK have had cloudier spells with patchy rain recently and there will be more to come next week. The result is that any Tropo results will be tailing off after this weekend and then it will be the turn of rain scatter as more unsettled weather arrives.
Meteor scatter is probably going to ease back slightly after the peak of the Perseids meteor shower last week, although there will still be a random component to keep things going, so stick to the hours around dawn for best results.
The solar conditions have shown the occasional uptick of the Kp index but not enough to get too excited about aurora, although it’s still worth keeping an eye out for values going above Kp=6.
We are still in the sporadic-E season and the recent input of Perseids meteor debris has provided some new fuel for Es, so it’s by no means all over. The dxcluster maps give a very good idea of the current directions that might prove rewarding.
The main North Atlantic jet stream will run across the UK into Scandinavia so paths to the east and northeast could do well, together with the usual paths to the south. In general, it’s still the time of year to check in the morning and again late afternoon for signs of Es activity, and if the band seems quiet then call CQ.
For EME operators, we have passed maximum Moon declination and minimum path losses for the month but there’s still a few more days of usable Moon time next week if you have a low horizon. Minimum declination and apogee are still over a week away.
144 MHz sky noise starts the week low, but climbs to high for the weekend starting Friday the 21st.