ARRL

ARRL Propagation Bulletin ARLP017 (1998)

SB PROP @ ARL $ARLP017
ARLP017 Propagation de KH6BZF

ZCZC AP17
QST de W1AW
Propagation Forecast Bulletin 17  ARLP017
From Lee Wical, KH6BZF
Kane'Ohe, HI  April 24, 1998
To all radio amateurs

SB PROP ARL ARLP017
ARLP017 Propagation de KH6BZF

Solar activity continues it's downward trend this week with the
possibility of a 27.5 day cyclic bottom in the mid to high 80's
centered around the 26th to 27th of April. Average sunspot
numbers were down this week from last week's report, and the
average solar flux was down to a daily mean of 100.6.

Wednesday's Solar Flux at 2000UTC was 87.6. The Solar Flux
peaked this month on April 8th at 140.6 level at 2000UTC. The
previous high level in this rotational sub cycle was on March
15th of this year, at 141.8 at 1700UTC.

Solar flux for this weekend, Friday through Sunday, is forecast
at the mid to high 80's with the return to the East limb of the
visible disk of several previously active regions. Look for some
DX activity on 10, 12 and 15 meters.

Next week look for flux values to drift slightly upward from mid
to upper 90's. Look for some unsettled conditions centered
around April 24th and again around May 8th. One cannot predict
solar perturbations or sudden active occurances. But, always
"expect the unexpected, and expect the expected".

Now that the solar activity is slightly lower than in early
April, 10 meters should be opening for a shorter period with
fair north south paths and an occasional north south, possibly
on 6 meters as well. Check 10 meters at 10AM local time, as I
always say, "check 10 at 10".

For the 30 meter band it is expected to be open to somewhere at
any hour. The only drawback for this band is QRN/QRM from some
of the 6,000 lightning strikes every minute, worldwide,
according to NASA data. Ditto for 40 meters, however some
DXpeditions are succeeding on the low bands. The low bands are
always worth checking on the gray and night time path.

For 20 meters occasional worldwide openings during a 24 hr
period with some polar paths open after Sunset to EU, Asia, with
good JA openings from the east coast. However, there was a
Satellite Proton Event beginning on 20/1400UTC with a Polar Cap
Absorption beginning 20/1615UTC and is expected to continue in
progress through Friday.

Also 17, 15 and 12 meters have had occasional worldwide openings
over the daylight paths as daylight hours are extended in the
northern hemisphere and shorter in the southern hemisphere.

Sunspot Numbers for April 15th through 21st were 79, 59, 70, 28,
35, 35, and 47 with a mean of 50.4, lower than last week. The
10.7 cm flux levels were 112.7, 106.4, 101.3, 98.5, 95.8, 97.7
and 92.0 with a mean of 100.6, also lower than last week's
report. The Alpha planetary indices were 04, 07, 15, 06, 04, 10
and 07, with a mean of 7.57.

Tad, K7VVV, will be back from his Maui honeymoon next week and
we hope he'll be up and around for more of his data and stats.
Thanks for the opportunity.
NNNN
/EX