ARRL

ARRL Propagation Bulletin ARLP024 (2013)

SB PROP @ ARL $ARLP024
ARLP024 Propagation de K7RA

ZCZC AP24
QST de W1AW  
Propagation Forecast Bulletin 24  ARLP024
From Tad Cook, K7RA
Seattle, WA  June 14, 2013
To all radio amateurs 

SB PROP ARL ARLP024
ARLP024 Propagation de K7RA

Average daily sunspot numbers declined over 32 points this week to
39.6.  Average daily solar flux was down more than 8 points to 99.2.
Tuesday's solar flux at 89.5 was the lowest since June 22-25 of last
year, when values ranged from 84 to 88.6. Likewise, Tuesday's
sunspot number of 14 was also the lowest since June 25, 2012 when
the sunspot number was also 14. Since then both numbers have been
recovering, with Wednesday and Thursday's sunspot numbers at 27 and
45, and solar flux at 93.3 and 98.9.

The latest prediction has solar flux at 105 on June 14-17, 100 on
June 18-19, 105 and 110 on June 20-21, 115 on June 22-24, 110 on
June 25, 105 on June 26-28, and 110 on June 29 through July 4.
Solar flux is expected to reach a minimum of 95 around July 7-8 and
another peak at 115 on July 18-21. Note that ARRL Field Day is June
22-23, right when solar flux is expected to be highest.

The predicted planetary A index is 5 on June 14-16, 8 on June 17-18,
5 on June 19-20, then 25, 18, 10 and 8 on June 21-24, 5 on June
25-27, then 30, 20, 10 and 8 on June 28 through July 1, 5 on July
2-4, 10 on July 5-6, 8 on July 7, and 5 on July 8 through mid-month.

A geomagnetic forecast comes to us this week from Petr Kolman,
OK1MGW, who sees quiet to unsettled conditions June 14, mostly quiet
June 15-18, quiet to unsettled June 19-20, quiet to active June
21-23, quiet to unsettled June 24, quiet June 25-26, quiet to active
June 27, active to disturbed June 28-29, quiet to unsettled June 30
through July 2, quiet to active July 3-4, mostly quiet July 5-6.

Word has come that the link to the W6ELprop installation file at
http://www.qsl.net/w6elprop/ is broken. Until it is restored you can
find it at ftp://150.214.111.198/pub/ham/propag/W6ELPropInst270.EXE.

Unfamiliar with FTP? FTP is File Transfer Protocol, and you can
paste that link into your web browser URL window, hit Enter, and a
download dialog should appear. W6ELprop works only on Windows
computers, and with it you can predict propagation from your station
to anywhere else, on any frequency between 3-30 MHz. If you have any
trouble installing, try right-clicking the file and running as
administrator.

The latest NASA prediction for Cycle 24 moves the sunspot peak back
to Summer 2013, but NOAA predicts the peak for the end of this year.
Check pages 16 and 17 at
http://www.swpc.noaa.gov/weekly/pdf/prf1970.pdf and note the highest
smoothed sunspot and solar flux numbers are predicted in November
and December 2013. These are smoothed international sunspot numbers,
with a scale quite a bit lower than the Boulder numbers reported
here.

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service web page 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/.

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 June 6 through 12 were 71, 76, 27, 41, 21, 14,
and 27, with a mean of 39.6. 10.7 cm flux was 109, 109.8, 103.2, 96,
93.3, 89.5, and 93.3, with a mean of 99.2. Estimated planetary A
indices were 17, 32, 10, 9, 13, 6, and 5, with a mean of 13.1.
Estimated mid-latitude A indices were 16, 26, 9, 8, 12, 6, and 5,
with a mean of 11.7.
NNNN
/EX