Last week the solar flux index remained steadfastly in the mid-70s. There was
only one very minor S class solar flare, on Sunday, 18 June. As predicted,
geomagnetic conditions were unsettled on the Sunday, but improved as the week
went on.
During a week when we had the
solar solstice, HF conditions were subdued. This is pretty much par for the
course this time of year. A change in the ionospheric chemistry with more
diatomic molecules and fewer monatomic species means it is harder to ionise. So,
paradoxically, despite having more sunlight, maximum useable frequencies are
lower during summer days. But, as we keep saying, you may find that 20m remains
open much later in the evening. If we had some sunspots it might have even
remained open all night.
Next week NOAA predicts more of the same with the solar flux index in
the range 70-74. Monday may be a little unsettled geomagnetically, but then the
rest of the week should be better with a K-index of around two.
At the moment, maximum useable
frequencies over a 3,000km path are around 14MHz, with occasional openings up to
18MHz. After dark, 30m and 40m will remain the best bands for DX, with 20m
probably closing in the late evening and usually before midnight. Sporadic E
openings on the higher bands should also remain prevalent as we head towards the
end of June.
VHF and up:
Sporadic E is still the main DX mode through to August, and on 16 June
we had one of the best events for a long time. Thousands of 144MHz QSOs were
reported to Make More Miles on VHF, including contacts from South Wales into the
Balkans.
The best policy to catch sporadic E is to maximise your chances by
checking the bands late morning and late afternoon or early evening to capture
the traditional two peaks of activity. Also look for late evening openings
towards Iceland, Greenland and beyond. Check the beacons and clusters for signs
of activity, remembering that an opening will build up in frequency as it
develops—first 10m, then through 6m and 4m, to perhaps 2m.
Despite the heatwave, tropo
conditions didn’t seem to materialise last week, with no cluster reports of
144MHz or above tropo QSOs over 600km from the UK.
Over the next week or so, it
looks as if the changeover to low pressure will be completed and for much of the
time there will be low pressure over Britain or nearby. This means that rain
scatter will be the best GHz bands DX option. Tropo will not feature strongly
again this week, but some short-lived overnight and dawn lifts are possible
before the heat of the day breaks down any surface temperature inversion.
Today shows high and falling
Moon declination, with low and increasing losses, so get your EME QSOs in the
early part of the coming week.