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ARRL Propagation Bulletin ARLP025 (2015)

ARLP025 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 25  ARLP025
From Tad Cook, K7RA
Seattle, WA  June 19, 2015
To all radio amateurs 

ARLP025 Propagation de K7RA

Solar activity weakened a little or increased slightly over the past
week, depending on which measure we choose. The June 11-17 average
daily sunspot number declined from 112.4 over the previous seven
days to 99.9 during the recent period. Average daily solar flux rose
from 131.4 to 135.9 over the same period.

The current outlook from NOAA and USAF has solar flux at 150, 152
and 153 on June 19-21,  148 and 140 on June 22-23, 135 on June
24-25, then 130, 120 and 110 on June 26-28, then 100 and 110 on June
29-30, 115 and 120 on July 1-2, 125 on July 3-4, 120 on July 5-6,
125 on July 7, 130 on July 8-10 and 125 on July 11-12. Flux values
then dip below 100 on July 19-24, and rise above 100 after July 26.

All of this looks pretty weak when compared to Solar Cycles 21-23,
but normal for current Cycle 24, which peaked in April and May of
2013, then again about 40 points higher in February and March 2014.
This is based on a 3-month moving average of Boulder sunspot
numbers. For a straight monthly average, we see May 2013 peaking at
125.6 and February 2014 at 174.6.

Since then, numbers have steadily declined, with the weekly sunspot
number averages for the last seven weeks at 60.9, 146.9, 92.1, 56.1,
34.3, 112.4 and 99.9. (See

Predicted planetary A index is 6 on June 19, 5 on June 20-22, 8 on
June 23-24, 6 on June 25, 5 on June 26 through July 4, then 25, 15,
12 on July 5-7, then 10, 5 and 8 on July 8-10, then 15, 12 and 8 on
July 11-13.

After this, planetary A index drops to 5, where it remains for the
foreseeable future until early August when it rises to 25,
indicating a geomagnetic storm. But early August seems a long time
from now, and far beyond the short term forecasts we usually

Petr Kolman, OK1MGW of the Czech Propagation Interest Group sees
quiet geomagnetic conditions on June 19-21, quiet to unsettled June
22-25, quiet to active June 26-27, quiet June 28-30, mostly quiet
July 1-2, quiet to unsettled July 3, active to disturbed July 4,
quiet to active July 5, quiet to unsettled July 6-8, mostly quiet
July 9-10, quiet to active July 11-12, quiet to unsettled July 13-14
and mostly quiet July 15.

OK1MGW expects increased solar wind July 4-5 and July 11-12.

At 0456 UTC on June 19 the Australian Space Forecast Centre issued a
geomagnetic disturbance warning, saying increased geomagnetic
activity is expected due to a coronal mass ejection on June 21-22:

"A coronal mass ejection has been observed in association with a
flare from region 2371 at 1736 UTC on June 18. The majority of the
CME material appears primarily directed to the NE of the Sun,
however further analysis suggests that the Earth will be impacted by
the edge of the CME around 09UT on June 21. Minor storm periods are
expected following the impact with major storm levels possible at
high latitudes."

June 21:  Active to Minor Storm, with major storm periods possible
at high latitudes.

June 22:  Mostly unsettled to active with minor storm periods
possible at high latitudes. also reported the possibility of M-class flares on
June 19, from sunspot region 2371, which is pointing toward Earth.

David Moore sent a link to an article about a new solar storm
prediction tool:

Rich Zwirko, K1HTV sent a 6 meter report:

"The Mid-Atlantic experienced some, but not much Es during this
year's June ARRL VHF Contest. The only DX worked to the east was
EA8DBM in the Canary Islands and VP9/WA4PGM, much closer in Bermuda.
I managed to work a number of Caribbean stations with C6ATA having
the most consistent signal. The first of two surprises occurred when
I snagged Dave, KM3T/R while he was roving in the rare FN51 grid on
Cape Cod, MA. The second surprise and the only double hop QSO to the
west occurred with only 2 minutes left in the contest when I worked
N6AMJ in DM14.

"On June 16, around 1:30 PM local time the first 6 Meter DX opening
from the K1HTV Virginia QTH to Eastern Europe occurred. I worked
HA5LI for Gyuri's first 6 Meter QSO with a U.S. station this year.
This was followed a few minutes later when I worked S59A. CT1HZE was
again into North America for hours, working as far west as Missouri
and Oklahoma. Joe's QTH on the southwestern coast of Portugal sure
helps. 4X4DK was briefly heard, but not long enough or loud enough
for a QSO.

"Some nice signals double hopped from Arizona and New Mexico later
that same afternoon. After a very slow start, it looks like the 2015
Es season is starting to ramp up."

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 the
numbers used in this bulletin, see An archive of past
propagation bulletins is at More good
information and tutorials on propagation are at

Archives of the NOAA/USAF daily 45 day forecast for solar flux and
planetary A index are in downloadable spreadsheet format at and .

Click on "Download this file" to download the archive and ignore the
security warning about file format. Pop-up blockers may suppress
download. I've had better luck with Firefox than IE.

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 11 through 17 were 101, 96, 97, 117, 107,
87, and 94, with a mean of 99.9. 10.7 cm flux was 139.9, 136.7,
136.1, 131.7, 134.8, 136.1, and 135.8, with a mean of 135.9.
Estimated planetary A indices were 9, 7, 10, 20, 14, 11, and 14,
with a mean of 12.1. Estimated mid-latitude A indices were 9, 8, 10,
19, 13, 10, and 14, with a mean of 11.9.


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