Propagation Forecast Bulletin #19 de K7RA:
W1AW Bulletin via the ARRL
May 10, 2013
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Propagation Forecast Bulletin #19 de K7RA:
QST de W1AW
Propagation Forecast Bulletin 19 ARLP019
From Tad Cook, K7RA
Seattle, WA May 10, 2013
To all radio amateurs
SB PROP ARL ARLP019
ARLP019 Propagation de K7RA
Average daily sunspot numbers remained about the same this week,
with the number nudging up from 120.9 to 121.7. The average of the
daily solar flux numbers went from 136.5 to 137.5.
An odd thing happened too. For two weeks in a row the average
planetary A index was the same as the mid-latitude A index. Last
week they were both 9.9, and this week both values were 8.
Predicted solar flux for the near future is 125 on May 10, 115 on
May 11-13, 110 on May 14, 105 on May 15-16, 110 on May 17, 120 on
May 18, 130 on May 19-20, 135 on May 21-22, then rising to 160 on
Predicted planetary A index is 5 on May 10-11, 8 on May 12-13, 5 on
May 14-20, then 15, 10 and 15 on May 21-23, 5 on May 24-27 and 15
and 10 on May 28-29.
F.K. Janda, OK1HH predicts the geomagnetic field will be quiet to
unsettled on May 10, quiet to active May 11-12, and quiet to
unsettled May 13-19.
The forecasts from OK1HH have been getting shorter. At first the
text was shorter because there was less variation over the forecast
period. So instead of shifting between five different levels of
activity over the course of nearly four weeks, we've seen two
levels, as in this week's forecast.
When I checked every bulletin since the first of the year, I found
that the number of days the forecast covers varied. The first two
bulletins of 2013 each covered 23 days, the next was 25 days, then
the fourth bulletin was 23 days, followed by 24 days on each of the
next three. The eighth (Propagation Forecast Bulletin ARLP008)
covered just 17 days, and the next six weeks varied from 21-24 days.
For bulletins ARLP014 through ARLP019 (this bulletin) the coverage
was 23, 19, 25, 24, 17 and 10 days. So the predictions for this
bulletin and the previous two all end on the same date, May 19. I
will see if I can find out what his methods are, and if perhaps
variation in conditions leading up the date of the forecast in some
way limits the number of days that are predicted.
At 0119 UTC today (May 10) I received an alert from
http://spaceweatherlive.com/ (not to be confused with
http://spaceweather.com/). The message is in Dutch, and it looks like
it says there was a "Class M3.95" solar flare. But the message does
not say whether the flare was geo-effective (Earth directed) or how
long it lasted.
I note that
http://spaceweather.com/ says the flare was just over the
Sun's eastern horizon, so it was not aimed at Earth, but it will
move toward Earth "in the days ahead." An event at the eastern
horizon should take about a week to move into a position where it is
aimed toward Earth, although another variable is the latitude of the
The English version of their web site is
http://www.spaceweatherlive.com/en. In the group of six graphs at
the top, five of them cover the previous two hours, and the Kp Index
covers the previous 24 hours.
At the bottom of the page is a flattened version of the STEREO image
http://stereo.gsfc.nasa.gov/. Instead of watching the rotating
globe, you see all sides of the sun at once.
David Moore sent a link to Phil Plait's "Bad Astronomy" blog (see
with an article and an impressive NASA video showing a May 1 solar
event, as seen from SOHO, SDO and STEREO. You can see Phil's website
http://www.badastronomy.com/index.html. Bad Astronomy refers to
Phil's attempts to correct popular misconceptions about science.
Lance Collister, W7GJ of Frenchtown, Montana wrote about recent
6-meter adventures: "Well, I think the SFI being over 145 on
Saturday May 4 probably moved the TEP further north than usual - and
with the early onset of Es, which just happened to connect me to
Texas just at the right time of late afternoon - I got my first
ionospheric link to South America on TEP this cycle. Saturday I
completed CW contacts with CX3AN, LW3EX, LU2DPW, LU5FZ, CX9AU,
LU5FF, and PY3FF. CX1FK, LU2DEK, LU9DO, CX5CR, LU6DC, PY3OR and
LU9EHF were worked on SSB. On Sunday, May 5, the SFI was still over
135 and I worked CE2AWW weakly on CW, although I didn't seem to have
a good strong Es link like on Saturday. Still searching for HC, CP
TEP refers to Trans-Equatorial Propagation. Check the W7GJ website
http://www.bigskyspaces.com/w7gj/. Lance invites us to use EME
(moonbounce) and check some of the references on his website.
Paul Harden, NA5N of Socorro, New Mexico wrote about a fascinating
project at the Very Large Array, the world's largest radiotelescope,
where he works:
"I am an electronics engineer at the Very Large Array (VLA) radio
telescope. My current project is our low-band system (60-500 MHz)
and the Long Wavelength Array (LWA) for 10-88 MHz. Though a few
years away, one of the science goals of LWA is to make real time 3D
maps of the ionosphere. The prototype system clearly paints the
locations of the E/F layers and it's depths as it migrates around.
Really cool, and when completed, should be made publicly available
on the web and a great tool for hams."
He sent this link to the project:
Jay Miller, N4NUI of Sandy, Utah wrote about what happened on
6-meters on May 2:
"During the afternoon of May 2 there was a great opening on
6-meters. It was obvious there were many paths open north and south
from the QSOs I could hear. I was mobile up in Antioch, Illinois
(EN52wk) and heard stations to the SE down to South Florida and SW
to West Texas. It was pouring rain and I couldn't get out of the
vehicle to tune the manual screwdriver without getting soaked to the
"I fixed that problem this afternoon (May 3) by driving up to
Milwaukee and buying a Little Tarheel II. I got it on the vehicle in
time to make a contact in the early evening with K5WLT and WP4O with
good signals as the opening started to close. Let's hope this is a
harbinger of things to come this summer.
"I travel for my job and I am sure glad I haul around a HF rig and a
Gorilla magnetic mount for the rental cars. A traveling ham using
rental cars has to ask for the same rental models each time once one
finds out how to get through specific firewalls to the battery."
Floyd Chowning, K5LA of El Paso, Texas wrote on May 4: "I had a nice
contact on 2-meter SSB this morning on 144.2 MHz at 1516 UTC with
WA7KYM in Cheyenne, Wyoming. Cheyenne is 639 miles from El Paso, TX
according to QRZ using grid squares. I am in DM61 and WA7KYM is in
DN71. This was my first contact with a Wyoming station."
Jon Jones, N0JK of Kansas wrote on May 4: "Interesting opening today
from the Midwest to South America.
"I was mobile (XYL driving) on K-10 just east of the K-7
intersection in Olathe and heard K3PA, K0HA and N0XA CQing or
calling some of the DX.
"No DX heard until 2150 UTC when PY3RO showed up on 50.115 MHz SSB.
He worked a local in Kansas City and I called after their Q. Had a
quick QSO with Raoul, he peaked to 5x7. During our QSO another KC
local came up on freq. and said my transmit audio was bad! (It was
due to voltage drop using a cigarette lighter plug to run the radio
in the car. I normally use jumper cables directly off the car
battery to run the radio). The next couple of times I went back to
PY3RO and listened, the local kept telling me 'OM your audio is
bad.' Guess he didn't hear the PY. First Brazil 6 meter QSO since
2001. I did not hear any other DX stations. My mobile set up is a 2
meter 5/8 wave whip and the FT-897."
Jeff Hartley, N8II of West Virginia wrote on May 7 about great
conditions back on April 7-11. He worked both Europe and Asia on 12
meters, and on April 9 on 10 meter CW running 5 watts he worked
9A4WY in Croatia who gave Jeff a signal repot of S9 plus 10 dB.
Jeff continued, "Throughout the last month, except during disturbed
conditions, 15 has been open to EU many hours, sometimes as late as
2200-2400 UTC and open about 90% of the days to Indonesia with good
signals from around 1300-1600Z. 20 meters is consistent every
morning with good VK signals from about 1115-1430 UTC or so and long
path southern Africans. On April 28, 15 meters was in good shape to
Russia in the UA1DZ contest logging Many stations in northern Europe
as well as UP0, UC0, and RN9. Many St. Petersburg area Russians were
active and it was fun working them as well as hearing them working
"On the April 29-30 with only 200 watts between 0200-0315 UTC, I had
a huge number of Russian stations call on 20 CW, some of the most
fun and biggest number of Russian callers in 40 years on the air. 43
stations were logged in an hour. Conditions were extremely good from
central Asia all the way east to DL on April 29, logging all Russian
call areas except for 0 as well as EX8AD and many Ukrainians. On
April 30, Asia was not quite as good, but many UA3 and UA6 area
stations called with the third QSO of the run being UA0YM in zone
23. Earlier around 2340-0030 UTC there was a large increase in EU
and Middle East activity on 17 meter CW logging UT3, A65BR, YO5,
SV1NN/3, and MU0FAL. On 20 CW I logged Z33Z. there was a real air of
excitement on both sides of the Atlantic over the great conditions."
If you would like to make a comment or have a tip for our readers,
email the author at,
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
Monthly propagation charts between four USA regions and twelve
overseas locations are at
Sunspot numbers for May 2 through 8 were 102, 139, 156, 103, 122,
118, and 112, with a mean of 121.7. 10.7 cm flux was 149.4, 147.9,
141.6, 137.1, 130.7, 128.7, and 126.9, with a mean of 137.5.
Estimated planetary A indices were 13, 6, 5, 7, 8, 10, and 7, with a
mean of 8. Estimated mid-latitude A indices were 11, 5, 5, 7, 9, 11,
and 8, with a mean of 8.
Source: W1AW Bulletin via the ARRL.
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