SB PROP @ ARL $ARLP050
ARLP050 Propagation de K7RA
ZCZC AP50
QST de W1AW
Propagation Forecast Bulletin 50 ARLP050
From Tad Cook, K7RA
Seattle, WA December 12, 2014
To all radio amateurs
SB PROP ARL ARLP050
ARLP050 Propagation de K7RA
Compared to the previous seven days, solar activity dropped over the
past week December 4 to 10 with average daily sunspot numbers down
63.6 points to 88.4, and average daily solar flux off 32.5 points to
139.6. But both numbers were higher on December 11, a good sign.
The latest forecast has solar flux at 155, 160, and 165 on December
12 to 14, 170 on December 15 to 17, 165 on December 18, 170 on
December 19 and 20, 165 and 150 on December 21 and 22, 155 on
December 23 to 27, 150 on December 28 and 29, 145 and 140 on
December 30 and 31, 135 on January 1 to 4, then 140, 145, 150, 155
and 160 on January 5 to 9 and 165 on January 10 to 12. It then
reaches a peak of 175 on January 14 and 15.
Predicted planetary A index is 5 on December 12, 18 on December 13,
15 on December 14 and 15, 12 on December 16 to 18, 10 on December 19
and 20, 5 on December 21 to 27, 8 on December 28 to 30, 10 on
December 31 and January 1, then 12, 25, 15 and 10 on January 2 to 5,
8 on January 6 and 7, 10 on January 8 and 9, 8 on January 10 to 12,
10 and 12 on January 13 and 14, and 10 on January 15 and 16.
Let's see what OK1MGW has for us in his prediction for geomagnetic
conditions.
OK1MGW sees quiet to active conditions December 12 and 13, quiet to
unsettled December 14 and 15, quiet to active December 16 and 17,
quiet to unsettled December 18 to 20, mostly quiet December 21,
quiet December 22, mostly quiet December 23 and 24, quiet December
25 and 26, quiet to unsettled December 27 and 28, mostly quiet
December 29 to 31, quiet to unsettled January 1 and 2, active to
disturbed January 3, quiet to active January 4 and 5, and quiet to
unsettled January 6 and 7.
He believes there will be an increase in solar wind on December 13,
16 to 18 and January 2 to 5.
Don't forget this weekend is the annual ARRL 10 Meter Contest (see
http://www.arrl.org/10-meter for rules and general information).
This is a really fun event, and due to the nature of ten meters, it
always holds many surprises. The Geminids meteor shower peaks this
weekend, and it is likely that ionized meteor trails could enhance
propagation at the high end of the HF spectrum.
It is also really easy to get a ten meter station on the air with
minimal effort. A half-wave dipole is only about 16.5 feet long for
this band, and you can hang it off just about anything to get it
some minimal distance in the air. Also, Technician Class hams can
participate in this one using SSB on 28.3 to 28.5 MHz and CW on 28.0
to 28.3 MHz. There is also an easy 10 meter vertical described at
the ARRL URL above for the 10 meter contest.
I was predicting conditions should be slightly better than they were
during the 2013 contest, with somewhat higher solar activity about
the same geomagnetic instability. But now the geomagnetic conditions
look a little worse.
The December 10 planetary A index for December 12 to 14 was 5, 12
and 12. The December 11 forecast shows 5, 18 and 15 for those same
days, or a little bit worse. These daily forecasts are at
ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ . Check it again today
after 2100 UTC. Maybe it will be better.
In 2013 the solar flux on Friday through Sunday on the contest
weekend was 141, 163 and 158, for an average of 154. This weekend
the predicted Friday through Sunday solar flux is 155, 160 and 165,
which averages out to 160. Last year the planetary A index over
those same three days was 3, 16 and 7, average value 8.7. This
year's forecast is 5, 18 and 15, with an average of 12.7. We'll see
what happens.
Check 2013 bulletins at
http://www.arrl.org/w1aw-bulletins-archive/ARLP051/2013 and
http://www.arrl.org/w1aw-bulletins-archive/ARLP052/2013 to see a
comparison with propagation from previous years and what the numbers
were on the contest weekend.
NOAA Space Weather Prediction Center has transitioned to their new
servers, so you will want to check
ftp://ftp.swpc.noaa.gov/pub/indices/DSD.txt and
ftp://ftp.swpc.noaa.gov/pub/indices/DGD.txt for solar flux, sunspot
and geomagnetic indices, and
ftp://ftp.swpc.noaa.gov/pub/forecasts/45DF/ for the daily 45-day
forecast. Of course Canada still serves up their same three times
per day solar flux numbers from their observatory at both
http://www.spaceweather.ca/solarflux/sx-5-flux-eng.php and
ftp://ftp.geolab.nrcan.gc.ca/data/solar_flux/daily_flux_values/fluxtable.txtTake your pick. HTML or plain text.
Dick Bingham, W7WKR sent along some interesting historical material
on early amateur radio, assembled by W2PA. Check it out at
http://w2pa.net/HRH/ .
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/.
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 December 4 through 10 were 137, 97, 73, 58, 77,
80, and 97, with a mean of 88.4. 10.7 cm flux was 157.6, 136.8,
128.7, 131.8, 132.6, 139.7, and 149.8, with a mean of 139.6.
Estimated planetary A indices were 11, 11, 13, 28, 17, 15, and 9,
with a mean of 14.9. Estimated mid-latitude A indices were 8, 8,
10, 19, 11, 12, and 6, with a mean of 10.6.
NNNN
/EX
