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ARRL Propagation Bulletin ARLP033 (2015)

ARLP033 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 33  ARLP033
From Tad Cook, K7RA
Seattle, WA  August 14, 2015
To all radio amateurs 

ARLP033 Propagation de K7RA

Solar activity is still soft, although sunspot numbers and solar
flux both increased this week.  Average daily sunspot numbers for
August 6 to 12 increased from 70.3 to 82.3, compared to the previous
seven days, and average daily solar flux went from 104.5 to 112.4.
Geomagnetic activity was moderate.
Predicted solar flux for the near term is 95 on August 14 and 15, 90
on August 16 to 21, 95 on August 22, 100 on August 23 to 26, 105 on
August 27 and 28, 110 on August 29 to 31, and then peaking at 115 on
September 1 to 7.  Solar flux drops below 100 on September 13 to 18.
Predicted planetary A index is 5 on August 14 and 15, 25 on August
16, 18 on August 17, 8 on August 18, 5 on August 19 and 20, 10 on
August 21 and 22, 12 on August 23, 10 on August 24, 5 on August 25
and 26, 12 on August 27, 10 on August 28 and 29, 5 on August 30
through September 1, then 12, 22 and 15 on September 2 to 4, then
20, 22, 12 and 8 on September 5 to 8, and 5 on September 9 to 12.
F. K. Janda, OK1HH of the Czech Propagation Interest Group predicts
quiet geomagnetic conditions on August 14, mostly quiet August 15,
quiet to unsettled August 16, quiet to active August 17, active to
disturbed August 18, quiet to unsettled August 19 and 20, quiet
August 21, quiet to unsettled August 22 to 25, active to disturbed
August 26, quiet to active August 27, quiet to unsettled August 28
to 30, mostly quiet on September 1, active to disturbed September 2,
quiet to active September 3 and 4, mostly quiet September 5 to 7,
quiet to active September 8 and quiet on September 9.
He expects an increase in solar wind on August 15 to 17, 25 to 27,
August 31 to September 1, and September 5 and 6.  OK1HH says the
August 15 to 17 increase is less probable when compared to
subsequent dates.
The Australian Space Forecast Centre issued a geomagnetic
disturbance warning at 0147 UTC on August 14.  The warning said a
partial halo CME observed in LASCO C2 imagery at 1448 UTC on August
12 associated with the long duration B7.0 flare and the filament
eruption from the southwest quadrant is expected to cause a glancing
blow early in the UTC day on August 16.  Expect periods of unsettled
to active levels in Australian region with chance of isolated
periods of minor storms at higher latitudes.
Richard Camp, WA7VGN lives in Las Vegas, Nevada (DM26jg) and sent a
message titled "6 meter meteor scatter" about conditions on August
12.  Six meters was wide open when he made a contact on 50.125 MHz
using SSB.  But when they tried to move off that frequency, it took
four attempts on different frequencies to find a clear spot to talk.
Richard said the band sounded like 20 meters at times with S9
signals all around.  The next day six meters sounded dead.
I don't recall if we've looked at these bulletins before, from the
American Association of Variable Star Observers.
Here is a recent monthly issue, from March 2015:
They have interesting information on Sudden Ionospheric
Disturbances, sunspot counts and solar flares.
Note the startling difference between current bulletins and one from
over 60 years ago:
Issues of this bulletin online go back 70 years, to 1945.
For more information concerning radio propagation, see the ARRL
Technical Information Service 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
My own 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 August 6 through 12 were 80, 95, 92, 87, 67, 87,
and 68, with a mean of 82.3.  10.7 cm flux was 121.6, 121.6, 121,
114.5, 106.2, 102.8, and 99.2, with a mean of 112.4.  Estimated
planetary A indices were 11, 20, 12, 10, 9, 8, and 12, with a mean
of 11.7.  Estimated mid-latitude A indices were 12, 17, 15, 10, 13,
8, and 12, with a mean of 12.4.


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