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ARRL Propagation Bulletin ARLP024 (2017)

ARLP024 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 24  ARLP024
From Tad Cook, K7RA
Seattle, WA  June 16, 2017
To all radio amateurs 

ARLP024 Propagation de K7RA

At 2311 UTC on June 14 the Australian Space Weather Forecast Centre
issued a geomagnetic disturbance warning.  "In the second half of
the first UT day (15 June) the solar wind is expected to be
influenced by a High Speed Solar Wind Stream.  On the second UT day
(16 June) the speed can reach 700 km/s.  The geomagnetic activity is
expected to reach active levels.  Isolated minor storm periods are
possible on 16 June.

15 Jun: Unsettled to Active 
16 Jun: Active"

Also, an update from Dr. Tamitha Skov:

And an older video from Dr. Skov:

We saw four zero sunspot days over the past week, so the average
daily sunspot number declined from 19.3 to 4.9 from the previous
seven days.

Average daily solar flux for this reporting week (June 8 to 14) was
74.4, down from 77.1 the previous seven days.  Average daily
planetary A index increased from 5.6 to 7.3 and average mid-latitude
A index went from 5.6 to 6.9.  Yes, that is correct and not a typo;
over the previous reporting week (June 1 to 7), mid-latitude and
planetary A index were both 5.6.

Predicted solar flux is 77 on June 16 to 23, 72 on June 24, 70 on
June 25, 75 on June 26 through July 7, 78 on July 8, then 78, 77,
78, 76 and 74 on July 8 to 12, 72 on July 13 to 21, 70 on July 22
and 23, and 75 on July 24 to 30.

Predicted planetary A index is 25, 12, 10 and 8 on June 16 to 19, 5
on June 20 to July 8, then 15, 12, 8, 15, 25 and 15 on July 9 to 14,
12 on July 15 and 16, 5 on July 17 to 30.

On June 14 issued a notification titled "A hole in
the sun's atmosphere".  It included a nice magnetic image.  Check

Or go to and check for "A Hole in the sun's
atmosphere" and if you don't see it, check the Archives in the upper
right corner, and set the date to June 14 or 15.  The magnetic image
is quite nice and very "granular" as techies often say today.

"This is a coronal hole (CH), a region where the sun's magnetic
field peels back and allows solar wind to escape.  A fast-moving
stream of solar wind from this coronal hole is expected to arrive on
June 16th, possibly sparking G1-class geomagnetic storms.
High-latitude sky watchers should be alert for auroras, especially
in the southern hemisphere where autumn darkness favors visibility.

Forecasters note that this stream is unusually fast with wind speeds
as high as 700 km/s.  Moreover, it is threaded with "negative
polarity" (south-pointing) magnetic fields.  Such fields do a good
job connecting to Earth's magnetosphere and energizing geomagnetic

Jon Jones, N0JK wrote to me on June 14:

"Nice 6M Es opening from KS to Caribbean June 12.  Logged C6ATA and
HH2AA til 2300z.  Seeing remarkable JT65 contacts spotted such as
9K2GS, VK4MA, VK8MS, E51WL, and SV9CVY to North America on June 13
and 13."
ARRL Field Day is next weekend, June 24 and 25.  See for info.  The latest forecast for
June 23 to 25 (we include the Friday before Field Day in case of any
predicted geomagnetic events on Friday) has changed from last week,
with A index at 5 on all three days and solar flux at 77, 72 and 70.

These predictions are updated daily, usually after 2100 UTC at .
Check this out:

From F. K. Janda, OK1HH of the Czech Propagation Interest Group, a
geomagnetic activity forecast for the period June 16 to July 11,

"Geomagnetic field will be: 
Quiet on June 20 to 22, 27, July 1, 4 and 5, 7 
Mostly quiet on June 26, 28, July 6 
Quiet to unsettled June 18 and 19, 26, July 3 
Quiet to active on June 17, 25, 29 and 30, July 2, 8, 11 
Active to disturbed on June (16, 23 and 24,) July (9 and 10)

Amplifications of the solar wind from coronal holes are expected on
June 16 to 19 (20, 26 and 27), July (8,) 9 to 11.  Parenthesis means
lower probability of activity enhancement and/or lower reliability
of prediction."

This weekend is the CW portion of the All Asian DX Contest.  See and for details.

Scott Avery, WA6LIE of Salinas, California wrote:

"The ARRL VHF contest pretty much fair to poor this year from
California CM96.

Condx poor at best, so digital modes prevailed.  Was hit and miss on
6 meters JT65 as band up and down a lot.

I missed about fifty percent heard due to band conditions.  Was
trying to encourage the new mode MSK144 for contest and general use,
as a lot "quicker" for those short openings I missed working on

I use MSK144 here on 50.280 and we have very regular morning
openings to SoCal and AZ, NM and other places.

Saying that, keep an eye on the digital modes when conditions are

My icing on the cake was working Hawaii on JT65; stations were KC7I,
NH6Y and K2GT.

Hope to see you on 6."

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 June 8 through 14, 2017 were 12, 0, 0, 0, 0, 11,
and 11, with a mean of 4.9. 10.7 cm flux was 74, 73.7, 74.7, 74.3,
75.2, 74.9, and 74.1, with a mean of 74.4.  Estimated planetary A
indices were 4, 5, 4, 17, 8, 8, and 5, with a mean of 7.3.
Estimated mid-latitude A indices were 5, 6, 5, 14, 6, 6, and 6, with
a mean of 6.9.


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