Last week the solar flux index declined from the low 80s to 74. The sun was
spotless, but propagation was dominated by strong geomagnetic storming on Sunday
the 28th of May. Sky watchers across many northern locations reported visible
aurora. This was due to the south-pointing Bz component of the interplanetary
magnetic field, which coupled more strongly with the Earth’s, allowing solar
particles to flow into the poles.
The K index soared to a high
of seven on the 28th, bringing a brief HF enhancement before auroral conditions
with suppressed maximum useable frequencies ensued. HF conditions were described
as “abysmal” by one GB2RS reader – we thought you should know why!
Next week the solar flux index
is predicted to remain around 70, although a new sunspot is heading around the
eastern limb of the sun and has already been producing C-class solar
flares.
A small solar coronal hole was
also facing Earth on Wednesday. This may cause unsettled geomagnetic conditions
around Friday the 2nd of June, and through this weekend. With National Field Day
this weekend, this could potentially result in an elevated K index, noisy bands
and subdued maximum usable frequencies. Otherwise, for field day we expect 20
metres to be the main daytime band, with occasional short-skip Sporadic-E
openings on 7MHz to 28MHz. Forty metres may be good in the morning and evening,
with 80 metres, and perhaps even 160m, coming alive at night.
We don’t expect much daytime F2 layer DX on 21MHz and higher, but do
take a look.
The next week or so is
dominated by a tendency for low pressure on the charts, mainly just to the
northwest of Britain. This is expected to produce a showery south-westerly
weather pattern, so good for rain scatter on the GHz bands, but it gives limited
options for tropospheric openings. That leaves us to hope for some Sporadic-E
propagation, especially for the 6m and HF CW NFD contests this weekend.
The good news is that we are
firmly in the Sporadic-E season. Since one of the key weather contributors to
Sporadic-E, jet streams, are likely to be present for much of the week, if we
have low K index figures there should be some Sporadic-E to work on VHF bands
from 10m through 6m and 4m, and perhaps even 2m. The jet streams are likely to
be over the near continent during this contest weekend, albeit as a weak
feature, but may offer a good direction for paths into Europe. There is also a
slight bias towards Scandinavia and the Baltic. Later in the weekend a new
Atlantic jet stream will reach Spain and may promote some Sporadic-E activity to
Spain early next week, moving east to support paths to Italy and Balkans midweek
onwards.
This is a poor week for
moonbounce, with low moon declination in the northern hemisphere and high
degradation, peaking Thursday and Friday. This may be a good time to check out
your antenna and receiver systems on sun noise.
This week sees one of the
summer low points in terms of meteor showers. There are no substantial showers
forecast, with just the low count Northern June Aquilids due around the 10th
June. But there are always random meteors to enhance those quiet days.
