Propagation News – 30 April 2023
What a busy week we’ve just had! It started with a massive G4 geomagnetic storm that saw the Kp index rise to eight with aurora visible as far south as Cornwall and the Channel Islands. This was due to a coronal mass ejection from a filament eruption on 21 April.
The 6m band came to life during the early stage of the storm with distorted aurora signals throughout the SSB and CW sections. However, the HF bands suffered, with MUFs down on the morning of the 24 April. The 25 April wasn’t much better with MUFs over a 3,000km path barely reaching 18MHz all day.
By Thursday 27 April the Kp index was still at four.
However, there were surprises to be had. Phil, GU0SUP reported that at 1300UTC on Monday the 24 April, he was amazed to work Yuris, VU7W on the Lakshadweep Islands on 10m FT8, with good signals both ways. He says the Kp index was at six and the regular FT8 frequencies on both the 10m and 12m bands were pretty much dead.
On Wednesday 26 April, Peter, G8BCG reported, on the CDXC reflector, that 15m FT8 was open all night via the long path to Australia, New Zealand and the Pacific.
It is always worth checking the HF bands during a major geomagnetic storm as there may be surprises to be had.
Next week the Space Weather Prediction Centre thinks that the Solar Flux Index will remain in the range of 135 to 140. The Kp index may remain around two to three. However, as last week showed, we are now really into uncharted territory, in terms of solar activity, with daily multiple solar flares and associated coronal mass ejections.
So, don’t be surprised if we have another major geomagnetic disturbance with an elevated Kp index.
VHF and up
The weather pattern in late spring often settles into a period of south-easterly winds from a rapidly-warming Europe and the signs are there for just such a flow during the coming week.
The sequence starts with unsettled weather and possible rain scatter from heavy April showers into the first weekend but, thereafter, a weak ridge of high pressure will move in to bring a chance of Tropo for next week. Paths along the east coast should do well, especially if there are large areas of sea fog and misty low clouds over the North Sea.
At longer timescales, the period towards the following weekend will see eyes looking towards a low to the southwest of the British Isles that could push some thundery rain into southern areas by the end of the week and again bring a chance of rain scatter on the GHz bands.
The jet stream pattern remains complex with several potentially useful flows that might be instrumental in prompting some early-season Sporadic-E propagation.
Last week, the Portuguese CS5BALG beacon on 50.036MHz in IM67, and CS5BLA on 50.0760MHz, made a welcome return. Sporadic-E can be very fleeting early in the season, but keeping a regular check on the usual beacons should give you a chance of being there at the right time.
The daily Sporadic-E blogs start on 1 May on www.propquest.co.uk and should give some clues as to any early-season options.
Lastly, the Sun has kept everyone busy recently with visible and radio auroras, so check the Kp index for aurora potential. And we are in a period when increasing meteor input is starting to help provide better meteor scatter prospects, as well as fuel for Sporadic-E. The Eta Aquariids has a broad peak zenithal hourly rate of around 50 next weekend on the 6 May.
Moon declination is high and falling, meaning shortening EME Moon windows and peak elevations. We passed apogee on Friday so path losses will fall throughout the week. 144MHz sky noise is low to moderate.
Category: GB2RS Propagation News
