Propagation News – 7 August 2016

This week saw the effects of yet another solar coronal hole, which pushed the Kp-index to four and five on Wednesday and Thursday. We predicted this last week, but were out by one day. Lacklustre sunspot activity also meant that the IOTA contest saw many contestants staying on 20m and below, with the odd foray up to higher bands. The solar flux index stayed in the mid-70s as the only sunspot that did appear rapidly dwindled away by Wednesday. On the bright side there were no solar flares to report.

Next week both NOAA and the US Air Force predict the solar flux index will be in the range 90-95. If correct this means we may see a slight uplift in HF conditions. However, continued unsettled geomagnetic conditions may work against us, especially around midweek when NOAA predicts the K-index will hit four again. Summertime D layer absorption and reduced MUFs are still impacting DX paths.

VOACAP predicts UK to New York on 20m CW is best from 2000-2200UTC with a 77 percent chance of success, and on 30m from 2200 to midnight with a maximum 81 percent chance. These figures drop by about 30 percent for SSB.

VHF and up propagation

There is a familiar look to the weather charts for the coming week, largely a story of low pressure to the north, moving into Scandinavia later. This means that tropo conditions may be limited initially, but pressure remains high over Biscay and northern France, so paths to the south from southern Britain offer the best of a poor showing. However, models do bring a large high close to the south-west and Ireland later, with perhaps some tropo possibilities. The low pressure to the north means that there will be showery periods, especially in the first part of the week, so there’s a chance for rain scatter on the gigahertz bands.

Hanging on to sporadic E into August is always a bit problematic, but there are likely to be some strong jet streams around, particularly over the UK and northern Europe. These may bring good prospects if you can be in the shack at the right time. A check during late morning and tea time should capture most events.

The Perseids meteor shower reaches its peak next Thursday and Friday so meteor scatter conditions will improve through the week. Moon declination is negative and the moon is at apogee on Wednesday so losses are high and moon windows are short. And that’s all for this week from the propagation team.

Category: GB2RS Propagation News