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ARRL Propagation Bulletin ARLP006 (2021)

ARLP006 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7RA
Seattle, WA  February 5, 2021
To all radio amateurs 

ARLP006 Propagation de K7RA

We just witnessed five days in a row with zero sunspots, but on
February 2 a small sunspot group (2801) appeared on our Sun's
northwest limb. It soon rotated off the Sun's visible area, and on
Thursday the sunspot number was back to 0.

We will probably see a few more days with no sunspots, but a return
after February 11 is possible when increased solar flux is forecast.

Average daily sunspot numbers declined from 28.1 reported in last
week's Propagation Forecast Bulletin ARLP005 to 3.3 this week.
Average daily solar flux dropped three points from 77.2 to 74.2.

Average daily planetary A index went from 9.4 to 6.7.

Solar flux over the next 30 days is predicted at 74 on February
5-11, 76 on February 12-16, 78 on February 17-22, 76 on February
23-25, 74 on February 26, 73 on February 27 through March 1, and 72
on March 2-7.

Predicted planetary A index is 5, 8, 16 and 10 on February 5-8, then
8 on February 9-10, 5 on February 11-20, then 20, 16 and 12 on
February 21-23, 5 on February 24-27, then 18, 12 and 8 on February
28 through March 2, 5 on March 3-5, and 10 on March 6-7. A coronal
hole may return on March 20-21 causing a rising A index.

Geomagnetic activity forecast for the period February 5 to March 2,
2021 from F.K. Janda, OK1HH.

"Geomagnetic field will be,
quiet on: February 18-19, 26-27
quiet to unsettled on: February 5-6, 9-13, 17, 24-25
quiet to active on: February 7-8, 14-16, 20, 23, 28
unsettled to active: February 21-22, March 1-2
active to disturbed: nothing predicted
"Solar wind will intensify on: February (8-10, 15-17, 20-22,) 23-24,
- Parenthesis means lower probability of activity enhancement.
- Predictability of changes remains low, as indications remain

N0JK reported, "Had some sporadic-E on 50 MHz the evening of
February 1 (February 2 UTC). XE2TT (DL44) on 50.313 MHz, 0205 UTC. I
was on Saturday night for a couple of hours January 31 UTC for the
CQ 160 M CW contest. Band noisy due to snow and high winds in
eastern Kansas. Made over 50 contacts with 5 watts and a rain gutter

More from Jon the next day:

"Some sporadic-E on 6 Meters February 2, 3 and 4. Es is rare in
February. I worked WA2VJL (EL16) on 50.313 MHz FT8 from my mobile
set up on the 2nd. See below.

"N0LL (EM09) is back on 6 Meters after repairing storm damage to his
antenna. On February 3 Larry worked XE2ML on 6 Meters. VK3OER in
Australia spotted K0TPP in Missouri! Possible sporadic-E-TEP across
the Pacific Ocean.

"XE2ML  21/02/04 0010Z  50313.0 EM09<ES>DL74            N0LL      
N0LL   21/02/04 0009Z  50313.0 DL74QB EM09 TNX qso 7    XE2ML

"Had some Es when I checked from my car at work. Decoded XE2OR,
N7WB/p, K0JY, and XE2ML.

"N7WB/P  21/02/03 2354Z  50313.0 EM28IX ES DM51BI       N0JK      

"VK3OER spotted K0TPP! 

"K0TPP   21/02/04 0036Z  50313.0 -16 CQ K0TPP correct!  VK3OER"

In response to last week's bulletin and the subject of super-huge
solar flares, Jon commented: "The VHF community is ready. Bring it

Article about solar magnetic waves and corona composition:

The latest report from Dr. Tamitha Skov, WX6SWW:

An audio tour of the Sunspot, New Mexico solar observatory:

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

For more information concerning radio propagation, see and the ARRL Technical Information
Service web page at, For an
explanation of numbers used in this bulletin, see

An archive of past propagation bulletins is at More good
information and tutorials on propagation are at

Instructions for starting or ending email distribution of ARRL
bulletins are at .

Sunspot numbers for January 28 through February 3, 2021 were 0, 0,
0, 0, 0, 12, and 11, with a mean of 3.3. 10.7 cm flux was 75.6,
75.5, 73.7, 73.4, 73.7, 72.9, and 74.3, with a mean of 74.2.
Estimated planetary A indices were 5, 3, 2, 1, 5, 17, and 14, with a
mean of 6.7. Middle latitude A index was 3, 2, 2, 0, 4, 11, and 10,
with a mean of 4.6.


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