Propagation News – 15 January 2017
The predicted poor geomagnetic conditions last week were not quite so bad, due to the incoming high speed stream from a coronal hole having a mostly north-facing Bz field. This was less likely to couple with the earth’s magnetic field and we didn’t see the very high K indices and poor auroral conditions we expected. Nevertheless, HF conditions remained largely poor, not helped by a total lack of sunspots.
The good news is that a sunspot is now rotating into view on the edge of the sun’s limb, but it is too early to say what effect this may have on HF propagation.
Looking ahead, conditions on the 15th and 16th should be reasonably settled, but the effects of another coronal hole may be felt again between the 16th and the 23rd. NOAA predicts the K index could rise again to five after the weekend.
The solar flux index should remain in the mid 70s giving maximum daytime critical frequencies over the UK of 5 to 5.8MHz. This means 60m is best for daytime inter-G contacts, with 40m reserved for longer skip and contacts into Europe. For DX, don’t expect to hear much above 20m, with occasional openings on 17m. There is still a slight chance of winter sporadic E, which could light up the higher bands.
The good news is that reports suggest 80m and 40m have both been open to DX at times.
VHF and up
This week promises much on the pressure charts, but unfortunately may not live up to expectations. If you can keep the snow off the antennas, there may be some tropo around, but it’s not guaranteed despite high pressure being predicted. Heavy snow does produce good scatter propagation on the gigahertz bands though!
The growth of a large area of high pressure next week will see the right sort of weather features for tropo on the VHF/UHF bands. As this high is growing in cold, dry air though, it may not be as good as you might expect.
Fairly shallow surface temperature inversions may give some limited enhancements, especially after overnight fog has formed. For a better chance of DX, we would need some moist Atlantic air to arrive under the main high pressure subsidence inversion at around 1,000 to 1,800 metres. This seems more likely over the north-western half of Britain towards the end of the week and will be evidenced by a sheet of stratocumulus cloud.
As we continue heading into the winter meteor activity minimum, continue to use the dawn peak in random activity for the best chance of meteor scatter QSOs.
Moon declination goes negative on Wednesday and losses are climbing with apogee just a week away, so get your EME contacts in early this week.
Category: GB2RS Propagation News
