ARRL Propagation Bulletin ARLP042 (2018)

Accessed on 20 October 2018, 0555 UTC, Post #734.


QST from W1AW and Hq ARRL, Newington, CT, 06111.

Please scroll down to read the full propagation forecast.

Comment:  Here is the latest propagation forecast from Tad Cook (K7RA) and his volunteer staff of observers and experts.  The report is exhaustive, thorough, and fully-referenced.  The report is an education in itself.

ARLP042 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 42  ARLP042
From Tad Cook, K7RA
Seattle, WA  October 19, 2018
To all radio amateurs 

ARLP042 Propagation de K7RA

Solar activity increased last week. Compared to the previous seven
days, average daily sunspot number increased from 1.6 to 12.6, while
average daily solar flux rose from 68.9 to 71. After six days with
sunspots making a re-appearance (October 12-17), there were no
sunspots on Thursday, October 18.

Sunspot area was listed at 0 on October 15-17, which means that the
area was less than 10 millionths of a solar hemisphere. See for daily sunspot area.

Geomagnetic indicators were quieter. Average daily planetary A index
dropped from 14.1 to 7.4, and average mid-latitude A index went from
10.3. to 7.3.

Predicted solar flux is 70 on October 19-22, 68 on October 23-26, 69
on October 27 to November 4, 70 on November 5-6, rising to 72 on
November 7-17, 70 on November 18-20, 69 on November 21 to December
1, and 70 on December 2.

Predicted planetary A index is 18, 10 and 8 on October 19-21, 5 on
October 22-23, 10 on October 24, 8 on October 25-26, 5 on October 27
through November 2, then 22 and 20 on November 3-4, 15 on November
5-6, then 8, 5, 12, 8 and 10 on November 7-11, 5 on November 12-13,
then 12, 18, 10, 5, 10 and 8 on November 14-19, 5 on November 20-21,
10 on November 22, 5 on November 23-29, then 22, 18 and 10 on
November 30 through December 2.

Geomagnetic activity forecast for the period October 19 to November
14, 2018 from F.K. Janda, OK1HH.

"Geomagnetic field will be:
Quiet on October and on November 2, 13-14
Quiet to unsettled on October 21, 24, 31, and on November 1, 8, 10, 12
Quiet to active on October 20, 27, 29-30, and on November 11
Unsettled to active on October 22-23, 25-26, and on November 5-7, 9
Active to disturbed on October 19, (28,) and on November 3-4

"Solar wind will intensify on October 19-20, 30-31 and on November
3-6, (7-9,) 10-13.

- Parenthesis means lower probability of activity enhancement.
- Again there are changes in the configuration of active areas, so
the predictability of the prognoses decreases and their compilation
is difficult."

From Dr. Tamitha Skov:

"Dear Tad,

Once again we find ourselves in a waiting game with the Sun. Not
only do we have a repeat offender-- a coronal hole that sent us fast
solar wind last month is about to send some again-- but we also have
several active regions firing small solar flares and mini-solar
storms. This burst of eruptive activity is a bit surprising because
the Sun has been in near hibernation for a while now. I captured my
excitement in the above picture (unfortunately, no way to display
the image in the propagation bulletin, but watch the video). I taped
labels '1' and '2' on my screen to show where two near-simultaneous
eruptions occurred on opposite sides of the Sun on October 12.
(Although I accidentally blocked the timestamp, the time of the
first was 1355 UTC and the second was 1415 UTC.) I wanted to share
this with you so when you watch the STEREO segment in the video, you
will know when and exactly where on the Sun to focus your eyes!

"So, the obvious question is, 'Will any of these eruptions hit
Earth?' Right now, likely not. But it does feel good to watch active
regions for solar storm launches again, even if this is only a
momentary burst of activity. Nonetheless, if none of the recently
launched mini-solar storms hit Earth, we still have fast wind from
coronal holes to keep us busy, which arguably could last us through
the entire solar minimum!

"Speaking of, in the forecast this week I talk about the fast solar
wind coming from the northern coronal hole and how long we must wait
before it arrives. I also look back at how much it affected us last
month and why its effects should be reduced this time around.
Overall, this is good news in the wake of Hurricane Michael. A
report I saw in News4JAX today said the North Florida section of the
American Radio Relay League is still actively looking for emergency
radio responders to fill the ongoing communication gaps across the
Florida Panhandle. Knowing that the impact of Michael is still being
felt, I am grateful that the bulk of Space Weather right now comes
from predictable sources like coronal holes. There is no doubt I get
excited seeing a flurry of eruptions occurring on the Sun,
especially when they might hit Earth. But I have to admit this week,
I would prefer to wait for nothing.

"Cheers, Tamitha"

NASA explains the difference between CMEs and solar flares. Thanks
to ARRL Contest Update and NW7US for the link:

NN4X sent this link concerning "NASA Scientists See Gravity Waves
from Storms in Earth's Atmosphere":

Jon, N0JK sent this note:

"A surprise 6 meter sporadic-E opening the evening of October 13. A
minor G-1 class geomagnetic storm was in progress. Kp = 4.

"Stations in the Gulf Coast and S. Texas had Es to the Midwest and
Rocky Mountain states. K0GU (DN70) said he heard the K4TQR/b (EM63)
for 2 hours. I heard the K4TQR/b on my mobile while driving on I-70
near Junction City, KS.

"Es is rare in October, the only month with less sporadic-E is

Martin WB5AGZ sent this:

"I don't know when it started but I was checking a few high HF
frequencies starting at about 0010 UTC on October 14 and found lots
of activity on several CB channels so I tuned up to 10 meters and
heard several signals such as a local rag chew in the Albany,
Georgia area on about 28.39 MHZ. At least one of the stations in the
QSO was running on generator power due to damage to the power grid
from Hurricane Florence.

"I then tuned up to 50.125 MHZ which is usually full of signals if
there is a real band opening but I heard no signal at all nor were
there any 10-meter repeaters audible from North Central Oklahoma. It
appeared that the E skip was anemic and the MUF was probably between
28.5 and 29 MHZ.

"The Winter (Es) season doesn't normally start until November but
sporadic-E isn't much for reading the rules and it can pop up about
any time. Continuously active low VHF and high HF frequencies are a
lot harder to come by than they used to be so it pays to store a few
frequencies in your receiver memories if you have them to spare.

"I have the following pre-sets stored, with all frequencies in MHZ:

"In AM, all WWV frequencies plus all the CHU frequencies, the
highest CHU frequency being 14.67 MHZ USB with carrier. Then there
is CB Channel 6 in which folks run enormous levels of power,
possibly trying to crowd-source an artificial ionosphere. Think
HAARP only a bit out of tune.

"If you don't hear any skip signals on 27.025, you can almost safely
assume there is not much happening between 25 and 50 or 60 MHZ.

"If you have FM reception capabilities, definitely pre-set 29.6 and
29.62 or everything between 29.6 and 29.68 MHZ as 10-meter repeaters
make excellent propagation indicators when they are in use.

"I just step through them quickly to see if anything non-local is

If you would like to make a comment or have a tip for our readers,
email the author at, .

For more information concerning radio propagation, see the ARRL
Technical Information Service web page 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 October 11 through 17, 2018 were 0, 11, 22, 22,
11, 11, and 11, with a mean of 12.6. 10.7 cm flux was 70.9, 71.6,
72.4, 71.5, 70, 69.7, and 70, with a mean of 71. Estimated planetary
A indices were 9, 5, 14, 6, 10, 5, and 3, with a mean of 7.4.
Estimated mid-latitude A indices were 7, 14, 12, 4, 7, 4, and 3,
with a mean of 7.3.