ARRL

Secure Site Login

ARRL Propagation Bulletin ARLP032 (2015)

SB PROP @ ARL $ARLP032
ARLP032 Propagation de K7RA

ZCZC AP32
QST de W1AW  
Propagation Forecast Bulletin 32  ARLP032
From Tad Cook, K7RA
Seattle, WA  August 7, 2015
To all radio amateurs 

SB PROP ARL ARLP032
ARLP032 Propagation de K7RA

Solar activity increased somewhat over this week's reporting period,
July 30 through August 5, compared to the previous seven days.
 
Average daily sunspot numbers increased from 47.9 to 70.3, while
average daily solar flux was up from 96.4 to 104.5.  Average daily
mid-latitude and planetary A index remained about the same, both
around 10.
 
At 2348 UTC on August 5, Australia's Space Weather Services issued a
geomagnetic disturbance warning.  A high speed stream of solar wind
from a coronal hole is expected to cause unsettled to active
conditions with possibility of magnetic storms over high latitude
regions on August 7, then settling down to stable conditions by late
August 8.
 
Earth is entering the debris field from Comet Swift-Tuttle, and the
resulting Perseid meteor shower should peak August 12 to 13.  This
offers the possibility of VHF meteor scatter communication on 6 and
2 meters, and possible enhancement of the ionosphere for upper HF
bands as well.
 
Predicted solar flux for the near term is 115 on August 7, 120 on
August 8 and 9, 115 on August 10 and 11, 110 on August 12 and 13, 90
on August 14 and 15, 95 on August 16 to 19, 90 on August 20 and 21,
95 on August 22 and 23, 100 on August 24 and 25, 105 on August 26 to
28 and 100 on August 29 through September 2.
 
Predicted planetary A index is 23, 15 and 24 on August 7 to 9, then
20, 12 and 8 on August 10 to 12, then 5 on August 13 to 17, then 12,
10, 8 and 12 on August 18 to 21, then 10, 5 and 8 on August 22 to
24, 5 on August 25 and 26, then 12, 18, 25, 12 and 10 on August 27
to 31, then 8, 5, 12, 18 and 8 on September 1 to 5, and 5 on
September 6 to 13.
 
OK1MGW predicts geomagnetic activity will be active to disturbed
August 7 and 8, quiet to active August 9, quiet to unsettled August
10 and 11, mostly quiet August 12 and 13, quiet on August 14 and 15,
quiet to unsettled August 16 and 17, quiet to active August 18,
quiet to unsettled August 19 to 22, mostly quiet August 23, quiet to
unsettled August 24, quiet to active August 25 and 26, active to
disturbed August 27, quiet August 28, quiet to unsettled August 29
and 30, mostly quiet August 31 and September 1, and quiet to active
September 2.
 
OK1MGW expects increases in solar wind on August 7 to 9 and 25 to
28.
 
Average daily sunspot numbers for July 2015 were 68.5.  This is down
from 77.4 in June and 83 in May.
 
For our three-month moving averages, the peak for the current cycle
was in 2014, when the averages centered on February and March were
146.4 and 148.2.  The three-month moving averages for the remainder
of 2014 were all above 100.  The averages centered on January
through June 2015 were 98.2, 78.1, 68.2, 72.4, 77.7, and 76.3.  So
the last figure, centered on June averages all the daily sunspot
numbers from May 1 through July 31.
 
We had no reports from readers, except K7HV in Seattle mentioned to
me that he observes reliable paths to Europe on 20 meters after
local sunset.
 
N2EIO, David Jennings of Ladys Island, South Carolina (between
Charleston and Savannah, Georgia) asked about how to use the numbers
we report in this bulletin, and we like to see the solar flux and
the sunspot numbers high, and the geomagnetic A and K index low.  At
the bottom of this bulletin are some resources, including a link to
the K9LA web site.  From there you can download W6ELprop for doing
your own predictions from your location.  So if we see that the
predicted solar flux is around 110, W6ELprop says from his location
at 32.44 degrees north, 80.64 degrees west a path to Hungary for
today on 20 meters would be best around 2100 to 0100 UTC, with
another possible opening around 0430 to 0530 UTC.  40 meters would
be best around 0000 UTC to 0500 UTC.
 
Checking paths to Costa Rica, 40 meters should be open all day and
night, with strongest signals from 0030 to 1030 UTC, and 20 meters
having the best path at 2130 to 0700 UTC.  Check out the projections
from your location.
 
For more information concerning radio propagation, see the ARRL
Technical Information Service at
http://arrl.org/propagation-of-rf-signals.  For an explanation of
the numbers used in this bulletin, see
http://arrl.org/the-sun-the-earth-the-ionosphere.  An archive of
past propagation bulletins is at
http://arrl.org/w1aw-bulletins-archive-propagation.  More good
information and tutorials on propagation are at http://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
http://bit.ly/1VOqf9B and http://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 http://arrl.org/propagation.
 
Instructions for starting or ending email distribution of ARRL
bulletins are at http://arrl.org/bulletins.
 
Sunspot numbers for July 30 through August 5 were 83, 71, 70, 51,
62, 68, and 87, with a mean of 70.3.  10.7 cm flux was 102, 100.7,
102.9, 101.5, 105.6, 106.8, and 112.2, with a mean of 104.5.
Estimated planetary A indices were 12, 14, 10, 11, 6, 7, and 6, with
a mean of 9.4.  Estimated mid-latitude A indices were 12, 16, 9, 13,
9, 9, and 7, with a mean of 10.7.
NNNN
/EX