SB PROP @ ARL $ARLP015

ARLP015 Propagation de K7RA

ZCZC AP15

QST de W1AW

Propagation Forecast Bulletin 15 ARLP015

From Tad Cook, K7RA

Seattle, WA April 11, 2014

To all radio amateurs

SB PROP ARL ARLP015

ARLP015 Propagation de K7RA

Average daily solar flux weakened over the past seven days, and so

did the outlook for the near term, at least until Thursday, April

10. Average daily solar flux declined from 149 to 142.2, while

average daily sunspot numbers remained about the same, moving from

130.4 to 129.3

From the NOAA/USAF 45 day forecast, predicted solar flux is 140 on

April 11-12, 145 on April 13-15, 150 on April 16-18, 140 on April

19, 135 on April 20-23, 130 on April 24-27, 125 on April 28 through

May 3, and 140 on May 4-6.

In yesterday's ARRL Letter we reported the prediction from

Wednesday, April 9 showed an average daily solar flux of 133.3 over

April 10-15. But just two days earlier, on Monday April 7 the

predicted average for the same period was 142.5, and back on March

30 the prediction for April 10-15 showed an average solar flux of

145.8. The predicted solar flux for April 10 was 150 on March 30,

140 on April 7 and 130 on April 9, which indicated a progressively

pessimistic outlook.

However, the April 10 prediction showed higher values. For April

11-18, average solar flux is predicted at 145.6, ten points higher

than the prediction for the same eight days on April 9, which was

135.6.

Predicted planetary A index is 5 on April 11, 8 on April 12, then 12

on April 13, 8 on April 14-15, 5 on April 16-18, 8 on April 19, then

5 on April 20 through May 5, and 8 on May 6-7.

OK1HH predicts a quiet geomagnetic field on April 11-13, mostly

quiet April 14, quiet to unsettled April 15-16, quiet to active

April 17, quiet April 18, mostly quiet April 19-20, quiet to active

April 21, quiet to unsettled April 22, mostly quiet April 23, quiet

on April 24, mostly quiet April 25-26, quiet April 27, mostly quiet

April 28, quiet on April 29, mostly quiet April 30, quiet May 1-2,

mostly quiet May 3, quiet to unsettled May 4, quiet May 5, quiet to

unsettled May 6, and back to quiet again on May 7-8.

A week ago (but too late for this bulletin) NASA released their

monthly Solar Cycle prediction, little changed from the March

version:

http://solarscience.msfc.nasa.gov/predict.shtml

The forecast begins, "The current prediction for Sunspot Cycle 24

gives a smoothed sunspot number maximum of about 70 in the late

summer of 2013. The smoothed sunspot number reached 73.1 in

September 2013, so the official maximum will be at least this high."

The March forecast said "The current prediction for Sunspot Cycle 24

gives a smoothed sunspot number maximum of about 69 in the late

summer of 2013. The smoothed sunspot number reached 68.9 in August

2013, so the official maximum will be at least this high."

These are smoothed numbers, averaged over a year, so that is why the

numbers from the end of last summer changed, because recent higher

activity is now averaged in.

Here is an interesting article, "Small Groups, Big Flares" from

Belgium's Solar Influences Data Center:

http://sidc.oma.be/news/245/welcome.html

Wayne Starnes, KU4V of Cary, North Carolina sent an email concerning

the radio blackout mentioned in last week's bulletin:

"Yes I also experienced the blackout during the CQ WPX, but do not

actually recall the time it happened. I was running on 10M as I

recall and BOOM 20+ atmospheric noise on the band! I then checked

10m-160m and it was the same intensity on every band. I have never

heard anything like it.

"Then, after a few minutes, it stopped and the bands seemed to be in

better shape actually.

"Then, Sunday 30-Mar at 1503 UTC while running 10m, YB2DX calls me,

very weak but we made it. At 1522 UTC YC0IEM calls me, again very

weak but we made it. At 1547 UTC 4Z5ML called.

"After the contest, 31-Mar after 0200 I worked the TX5 guys on 10

and 15.

"Amazing and interesting propagation this past weekend."

Chris Wreck, K2HVE of Bayonne, New Jersey wrote: "Yes! It was the

same at my station, K2HVE. I am located in Hudson County, 1.5 miles

SW of the Statue of Liberty and 2.5 miles SW of WTC in lower

Manhattan. I was on 20 meters during the CQ WPX Contest on Saturday

29 March working EU and Russian stations one after another when

around 1750 UTC the whole band was wiped out. Nothing but noise at

an S3 level. It was like somebody pulled my antenna wire out. I

began checking antenna connections on my IC-7600 and found nothing.

"Very shortly a NOAA SWPC alert came through noting the solar flare.

The disturbance lasted about 30-45 minutes, then slowly the US

Stations came back up and shortly after the EU Stations. In an hour

it was like nothing had ever happened. In all the years I never had

anything so sudden happen at my QTH regarding Ole' Sol."

Jon Jones, N0JK sent a correction concerning working long path on

6-meters.

"Fred, KH7Y made the first 6 meter Hawaii to Europe TPL (trans-polar

longpath) contact of solar cycle 24 with IT9 on February 28. But it

was TPL going southeast of Hawaii. It took place in the early

afternoon HST (Hawaii Standard Time).

"I think I made the first Hawaii to Europe TPL contact of Solar

Cycle 24 going southwest of Hawaii March 30 with S57RR. It was

around midnight HST for me."

Jon also reported, on April 10: "During the last week many contacts

were made in the afternoon from the Gulf Coast and southern parts of

the Midwest to CX, LU and PY in South America on 6 meters. A few

fortunate hams in AR, MO and OK worked the Falkland Islands. The

propagation mode is 'afternoon TEP.' This link has information about

this propagation mode:

"http://home.iprimus.com.au/toddemslie/aTEP-Harrison.htm

"Not much to report since arriving home (to Kansas) from Hawaii. I

heard CE4WJK working CO2QU on April 6 at 2100 UTC on 50.140 MHz.

"Today April 10 heard the K5AB/b 50.060 MHz on Es at 2350 UTC."

Thanks, Jon!

Scott Craig's Solar Data Plot Utility has an updated data file,

useful if you are just starting out with the program. Otherwise you

update it auto-magically weekly with this bulletin.

You can find it at http://www.craigcentral.com/sol.asp .

This program runs on Microsoft Windows, but I've never been able to

use it on Windows 7 computers, so I've used a virtual XP mode or

just my old XP machine. Now I see Microsoft has ended support for

XP.

This weekend is the Japan International DX CW Contest. See details

at http://jidx.org/ .

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 April 3 through 9 were 137, 174, 172, 127, 106,

94, and 95, with a mean of 129.3. 10.7 cm flux was 153, 156.9,

142.1, 140.9, 139.9, 132, and 130.6, with a mean of 142.2. Estimated

planetary A indices were 6, 6, 14, 5, 11, 5, and 5, with a mean of

7.4. Estimated mid-latitude A indices were 7, 5, 11, 3, 10, 4, and

5, with a mean of 6.4.

NNNN

/EX