QST de W1AW  
Propagation Forecast Bulletin 35  ARLP035
>From Tad Cook, K7RA
Seattle, WA  August 28, 2015
To all radio amateurs 

SB PROP ARL ARLP035
ARLP035 Propagation de K7RA

We saw just one new sunspot group (AR2403) over the reporting week
(August 20 to 26), but it was a big one, directly facing Earth on
August 23. Average daily sunspot numbers rose 32.3 points to 69.7,
while average daily solar flux increased 28.7 points to 119.7.
 
Another new sunspot appeared on August 27, numbered 2405.
 
The average daily planetary A index dropped from 21.4 to 14.7,
compared to the previous seven days. The most active days were
August 23 and 26 when planetary A index was 28 and 30, caused by
streams of solar wind.
 
At 0012 UTC on August 27 Australia's Space Weather Services issued a
geomagnetic warning. They warned that increased geomagnetic activity
is expected on August 27 and 28 due to a high speed wind stream
coming from a coronal hole. On August 27 expect quiet to unsettled
conditions with active to minor storm periods, and on August 28 look
for active to unsettled geomagnetic conditions.
 
Predicted solar flux is 110 on August 28 and 29, 105 on August 30,
100 on August 31, 95 on September 1 to 3, 100 on September 4 and 5,
95 on September 6 to 9, then 90, 85, 95 and 100 on September 10 to
13, 105 on September 14 to 19, 120 on September 20 and 21 and 125 on
September 22 to 24. Solar flux values drop below 100 on October 3 to
9.
 
Predicted planetary A index is 18, 12, and 8 on August 28 to 30, 5
on August 31 through September 1, then 12, 20, 15, 10 and 8 on
September 2 to 6, then 5 on September 7 to 11, then 12 on September
12, 15 on September 13 and 14, then 5, 10, 5, 8 and 20 on September
15 to 19, and 28, 20, 12, 18, 12 and 8 on September 20 to 25, and 5
on September 26 to 28.
 
F. K. Janda, OK1HH sent his weekly geomagnetic forecast. He predicts
quiet to active conditions August 28, quiet to unsettled August 29,
quiet on August 30, mostly quiet August 31 through September 1,
quiet to active September 2, active to disturbed September 3, quiet
to unsettled September 4 and 5, mostly quiet September 6 and 7,
quiet to unsettled September 8 to 10, quiet to active September 11,
active to disturbed September 12, quiet to active September 13,
quiet to unsettled September 14, quiet to active September 15 and
16, mostly quiet September 17, quiet to unsettled September 18,
active to disturbed September 19, mostly quiet September 20 and 21,
quiet to active September 22, and active to disturbed September 23.
 
OK1HH expects increases in solar wind on August 28 and 29, September
1 to 5, 10 and 11, 16 to 20, (although 16 and 17 is less certain),
and September 23.
 
NASA issued a new commentary for the current sunspot cycle, this
time with the new V2.0 sunspot numbers, which read higher than the
old standard. Historic numbers are also being revised around this
new standard.
 
You can read it at solarscience.msfc.nasa.gov/predict.shtml .
 
Using the new numbering system, the maximum of 101 in late 2013 was
revised upward from 72, and the peak of 116.4 in April 2014 was
increased from 81.9.
 
Don't forget, the Autumnal Equinox is on Wednesday, September 23,
2015 at 0822 UTC, ushering in the Fall DX season.
 
Dick Bingham, W7WKR of Stehekin, Washington sent an interesting link
concerning over-the- horizon HF radar operating in Virginia:
 
https://cryptome.org/2015-info/navy-rothr/navy-rothr.htm
 
Jimmy Mahuron, K9JWJ in Salem, Indiana had some observations on
daytime regional net operations on 40 and 75 meters.
 
'40 meters (7.191 MHZ) on the RV Service Net was made difficult by
the G2 Geomagnetic Storm this morning (August 27), from net time
which is 7 to 9 AM local time (1100 to 1300 UTC).
 
3.74 MHz was much quieter than 7.191 MHz and WWV was very light on
10 MHz and not audible at times.
 
3.74 MHz was relatively quiet at the home QTH but just the reverse
for other hams on frequency. The relays on 7.191 MHz made the net
possible and if not for the relays would be virtually impossible.
Thanks to all on the RV Service Net.'
 
The geomagnetic storm that Jimmy mentioned produced some visible
aurora. See wapo.st/1IlquhG and wapo.st/1PyL2c0 for
reports from the Washington Post weather blog.
 
David Moore sent another interesting article, this time about
coronal heating. See bit.ly/1LwgPMZ .
 
For more information concerning radio propagation, see the ARRL
Technical Information Service at
arrl.org/propagation-of-rf-signals. For an explanation of the
numbers used in this bulletin, see
arrl.org/the-sun-the-earth-the-ionosphere. An archive of past
propagation bulletins is at
arrl.org/w1aw-bulletins-archive-propagation. More good
information and tutorials on propagation are at k9la.us/.
 
My own archives of the NOAA/USAF daily 45 day forecast for solar
flux and planetary A index are in downloadable spreadsheet format at
bit.ly/1VOqf9B and bit.ly/1DcpaC5 .
 
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 arrl.org/propagation.
 
Instructions for starting or ending email distribution of ARRL
bulletins are at arrl.org/bulletins.
 
Sunspot numbers for August 20 through 26 were 68, 78, 72, 93, 71,
61, and 45, with a mean of 69.7. 10.7 cm flux was 102.8, 110, 116.9,
133.1, 127.7, 121.2, and 126.2, with a mean of 119.7.  Estimated
planetary A indices were 13, 6, 9, 28, 8, 9, and 30, with a mean of
14.7. Estimated mid-latitude A indices were 11, 6, 8, 23, 7, 8, and
19, with a mean of 11.7.