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Propagation News – 13 January 2019

RSGB
January 11, 2019
This week saw relatively-settled HF conditions after the effects of a geomagnetic storm that impacted Earth at the weekend had passed. The Kp index was mostly around one or two thanks to a reduced solar wind. A small solar coronal hole did become Earth-facing on Wednesday, the 9th, but its effects, if any, won’t be felt until around Friday, the 11th. The Sun’s disk remained spotless, with the solar flux index around 71-72.

The propquest.co.uk site shows that daytime critical frequencies remain around 3.5-5MHz, although there have been some high spots where it has hit more than 6MHz. These can spark short-term long-range HF propagation at maximum usable frequencies of more than 18MHz, so it is worth keeping an eye on the higher bands. Otherwise, the upper bands have been fairly lacklustre with mostly contacts around Europe, as can be expected at this point in the sunspot cycle.

Next week NOAA has the solar flux remaining around 70 with settled geomagnetic conditions, other than around the 16th when the K-index may rise to four due to recurrent coronal hole activity.

A check with the new animation facility at predtest.uk shows that the upper HF bands currently favour one-hop contacts into southern Europe with occasional openings to North Africa. Forty metres should be open to Europe both day and night with the possibility of some weaker longer paths opening up around sunset and after dark.

Eighty metres remains a good evening and night-time band, but make the most of it now as the nights are starting to get shorter.

VHF and up:
The weekend started with a residual high pressure area, by now displaced to the south-west of Britain. This means that the bulk of the country is under a weaker ridge. This will obviously favour the western side of the country, which is closest to the high, for any tropo activity.

As the week progresses, the high weakens further and the pattern becomes more like a showery north-westerly with little chance of tropo and rather more breeze, especially over the north and down the eastern side of the country. This type of weather can produce an opportunity for rain scatter on the Gigahertz bands as big reflective shower clouds drift past the coasts.

We are in the quiet period of the year for meteor activity with few major showers until April. There are, though, always opportunities for random meteor scatter contacts peaking around dawn when the earth is rotating towards the main orbital flux of meteoric particles.

Lunar declination is positive again, so moon windows will lengthen as the week progresses, and path losses will fall. Early in the week, moonrise will be around lunchtime, and getting later over the coming week.

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