September 18, 2015
Despite ongoing solar coronal holes,
and their contribution to the high-speed solar wind, HF conditions have fared a
little better than in previous weeks. This is due to the traditionally better
autumnal HF conditions, which should improve further as the month goes on.
Despite the geomagnetic K-index never really dropping below three, and often
hitting five, maximum usable frequencies have exceeded 18MHz at times, sometimes
making 21MHz. Radio hams waiting for decent 10m openings may still have to wait
another month though—and then they may be sparse, given the poor solar flux
index. NOAA predicts that the solar flux index this week will be around 105,
dropping to 90. The K-index may suffer yet again from the effects of the
high-speed solar wind.
Thursday and Friday are predicted to
be the most unsettled, geomagnetically speaking.
The Six Gs DXpedition to Niue Island
in the Pacific should be under way by now. The best predicted paths to E6GG look
to be on 20m and 17m, with an optimum short-path opening on 17m between 1000 and
1400UTC, and again at 1800. There may also be a long-path opening on 17m around
1900UTC.
As a reminder, September is a good
month for north-south paths on HF, such as UK to South Africa and South America.
In between geomagnetic storm events we should also see the lower bands becoming
more usable too.
VHF and up propagation:
Today
looks promising for tropo conditions to the continent and the south-east, but
this is only likely to last for a day or so. By Wednesday there may be some
tropo from the west of the UK which could couple into the Atlantic tropo systems
off Iberia and west Africa.
The remnants of tropical storm Henri
brought some nice rain scatter propagation to 5.7 and 10GHz last week, but sadly
few UK stations were active to take advantage of it. Next week is looking drier,
but still be aware of the possibility of rain scatter on the GHz bands in any
showers that might crop up. Watch out for auroras as there are a number of
sunspots with the potential for M-Class solar flares.
The sporadic E season is over so
it’s unlikely that there will be much in the way of propagation by that mode on
the VHF bands.
There are no major meteor showers
this week so keep looking in the early mornings for the best random meteor
scatter opportunities.
For EME operators, the moon is at
its lowest declination today, so we will see short Moon windows, but losses will
be at their lowest at perigee on Monday.