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.txt

Take 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