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ARRL Propagation Bulletin ARLP034 (2018)

ARLP034 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 34  ARLP034
From Tad Cook, K7RA
Seattle, WA  August 24, 2018
To all radio amateurs 

ARLP034 Propagation de K7RA

Australia's Space Weather Services released this bulletin at 0700
UTC on August 24:


There is a chance of a glancing blow from a slow moving coronal mass
ejection (CME) that may arrive over the next 24 hours resulting in
periods of Active to Minor Storm conditions.

FROM 24 to 25 AUGUST 2018

24 Aug:  Quiet with the chance of Active to Minor Storm periods
25 Aug:  Unsettled"

And now, the ARRL Propagation Bulletin:

Average daily sunspot number over the past reporting week was 13, up
from 3.4 during the prior week.  But average daily solar flux was
down slightly, declining from 68.7 to 67.5.  Average daily planetary
A index rose from 6.9 to 10.1, and average mid-latitude A index
changed from 7.3 to 10.4.

Sunspots have been visible every day for ten days in a row as of
August 23, since first appearing on August 14, following a lull
since June 27, with only three days showing any sunspots at all
after that, July 21, and then on August 1 and 2.

For a view of recent quarterly sunspot numbers and solar flux,

Predicted solar flux is 70 on August 24 to 30, 68 on August 31, 66
on September 1 to 5, 67 on September 6 to 10, 68 on September 11 to
15, 67 on September 16 to 19, 66 on September 20 through October 1,
and 67 on October 2 to 7.

Predicted planetary A index is 8, 12, 8, 8 on August 24 to 27, 5 on
August 28 through September 2, 12 and 8 on September 3 and 4, 5 on
September 5 and 6, 15 on September 11 and 12, 12 on September 13 and
14, then 12, 18, 15, 12 and 10 on September 15 to 19, 8 on September
20 and 21, 5 on September 22 to 29, 15 and 10 on September 30
through October 1, 5 on October 2 and 3, 8 on October 4, and 5 on
October 5 to 7.

The above numbers are updated daily, usually after 2205 UTC at:

Geomagnetic activity forecast for the period August 24 til September
19, 2018 from F.K. Janda, OK1HH.

"Geomagnetic field will be:
Quiet on August 24, 31, September 1 and 2, 8 to 10
Quiet to unsettled on August 25, 30, September 5 and 6, 17 to 19
Quiet to active on August 26 and 27, September 4, 8, 16
Unsettled to active on August 28 and 29, September 3, 7, 11 to 15,
Active to disturbed -

Solar wind will intensify on August (28), September (10 and 11,) and
14 to 17.

- Parenthesis means lower probability of activity enhancement.
- Reliability of predictions remains low.

F. K. Janda, OK1HH"

Bil Paul, KD6JUI, who often operates portable from a kayak in
Northern California freshwater channels near Sacramento, wrote on
August 19:

"I heard about the recent burst of solar activity while vacationing
at Lake Almanor in northern California.  I noticed the solar flux
took a temporary bump upward to 79 and I hoped for improved
propagation.  However, the only result I saw was increased levels of
static noise (which temporarily reached S7 on my transceiver).  The
max usable frequency for me as a QRP operator was still 40 meters

Bil published an article in the November 2016 issue of QST about
operating on HF from fresh waters and the antenna he built for his

I have not confirmed with him when he operated from the lake, and I
cannot find a burst in solar activity until I look back at June
20-22.  That must be it.  The solar flux numbers at the Penticton,
BC observatory (measured three times per day, although the local
noon measurement at 2000 UTC is official solar flux number for the
day) over those three days was 80.5, 82.1, 82.4, 82.1, 81.5, 81.6,
81.1, 80.3, and 79.9."

We must look back at 2017 to find any numbers like that.

I replied to Bil, "We won't often see improvement in MUF after a
brief rise in solar activity.  It helps, but needs to be sustained.

Maybe in 2021, if we're lucky."

Steve Sacco, NN4X of St. Cloud, Florida wrote on August 17, and
noted contacts and stations he heard using WSJT-X on six meters at
50.313 MHz.

Steve was excited about hearing 9K2GS (Abdullah Bin Hamad, in
Kuwait) from 1307-1311 UTC, but could not work him.  He wrote,
"Multiple decodes, but no QSO. Still super cool, ESPECIALLY for
this late in the summer E's season."

He also logged K4MIL, W4TAA, VE2DLC, KB8ZR, N3DGE, N4OYT, VE9HF,
K0PT, WA2TP, and N2SAB.

Jon Jones, N0JK wrote early on August 24, 2018

"A remarkable Es season, long lasting.  Maybe the noctilucent clouds
played a role ?  Or upper atmosphere circulation. - Jon"

Dr. Tamitha Skov wrote on August 23:

"I have a new 'forecast shortie' ready for viewing on You Tube, but
I wish it came without a warning label.  A solar storm set to hit
Earth on Saturday nearly mirrors Hurricane Lane, which is coming
dangerously close to the Hawaiian Islands now and will hit by this
weekend.  At the time of this writing, the storm is a Category 4.
The last time the islands got hit with a Category 4 storm was
Hurricane Iniki in 1992.  I've been getting messages from people,
who remember living through Iniki, asking me if amateur radio will
be impacted by this coming solar storm.  They told me HF radio was a
lifeline during Iniki and they wanted the comfort of knowing they
would be able to rely on it again.  All I could do was wince.

The Hawaii Emergency Management Authority declared yesterday that
amateur radio will be the emergency communications of choice between
the islands during Hurricane Lane's passage.  As such, I will be
sure to keep you updated on the impacts of the solar storm when it
arrives.  I might even do a live public broadcast if it looks like
it could help emergency responders know what kinds of disruptions
they might be facing and/or communications windows they might have.
Again, a huge THANK YOU to the Patreon members, who are making
these 'forecast shorties' possible.  Frequent forecast updates such
as these prove so critical at times like now -- you are helping
families and communities stay safe.


Here is her latest video:

For more information concerning radio propagation, see the ARRL
Technical Information Service at  For an explanation of
numbers used in this bulletin, see

An archive of past propagation bulletins is at  More good
information and tutorials on propagation are at

Monthly propagation charts between four USA regions and twelve
overseas locations are at

Instructions for starting or ending email distribution of ARRL
bulletins are at

Sunspot numbers for August 16 through 22, 2018 were 12, 11, 11, 15,
15, 15, and 12, with a mean of 13.  10.7 cm flux was 68.3, 67.3,
67.2, 66.8, 68, 67.8, and 66.9, with a mean of 67.5.  Estimated
planetary A indices were 11, 13, 12, 8, 14, 7, and 6, with a mean of
10.1.  Estimated mid-latitude A indices were 11, 14, 11, 8, 15, 6,
and 8, with a mean of 10.4.


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