[W4HM Spaceweather] W4HM Daily HF Radio Wave Propagation Forecast #358

Sun Dec 24 11:11:38 EST 2017

Hello to my fellow hamateur radio and SWL radio enthusiasts around the world. 

Welcome to my “not for profit” daily W4HM Daily HF Radio Wave Propagation Forecast.

It’s the only daily global HF radio wave propagation forecast on the planet.

Created and disseminated by Thomas F. Giella, W4HM in Lakeland, FL, USA

If you find this daily HF radio wave propagation forecast useful to your hamateur and SWL radio activities, feel free to drop me a line and let me know that at

thomasfgiella at gmail.com

Feel free without prior permission to redistribute this daily HF radio wave propagation forecast, as long as you redistribute it in its entirety and give me credit for it.

Supporting images associated with this daily HF radio wave propagation forecast can be found in my Facebook account at 

https://www.facebook.com/thomasfranklingiellaw4hm

and at

http://lists.contesting.com/mailman/listinfo/spaceweather 

but without supporting images.

It's a NO SPAM voluntary "opt" in email type group hosted by contesting on line (COL), so you have to sign up by using an existing email address and creating a password.

And last but not least I also post solar, space and geomagnetic weather goings on and some images in my Twitter account at 

https://twitter.com/GiellaW4hm .

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#358 Issued Sunday December 24, 2017 at 1615 UTC

Important Solar, Space & Geomagnetic Weather Indices-

The daily solar flux index numbers (DSFI) were 76.6 76.2 76.0.

The official daily sunspot number (DSSN) was 22.

Sunspot group #12692 was located near N18E04 with a relatively simple beta magnetic signature capable of producing isolated small C class solar flares.

In 2017 there had been 101 days with a daily sunspot number (DSSN) of 0.

The 24 hour period 3 hour interval planetary K index (Kp) had been at a quiet geomagnetic condition of 

1 2 1 1 0 0 1 1. 

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Global Daily HF Radio Wave Propagation Forecast- 

HF radio wave propagation condition trend Dec 24, 2017- steady state

HF radio wave propagation condition trend Dec 25, 2017- steady state

Northern Hemisphere Radio Wave Propagation Forecast g-

3150-3400, 3500-4100, 4750-5050, 5700-6300 kHz- very good at night and poor to fair at day,

6900-7800, 9200-9995, 10000-10150, 11500-12200 kHz- very good at night and fair at day,

13570-13850, 14000-14350, 15005-15900, 17450-17950, 18068-18168 kHz- very poor at night and good at day,

21000-21850 kHz- very poor at night and fair to good at day,

24890-24990, 25600-26100 kHz- very poor at night and fair at day,

28000-29700 kHz- very poor at night and poor at day.

Excellent- S9+10 or >

Very Good- S9 +1-9

Good- S8-9

Fair- S4-7

Poor- S1-3

Very Poor- S0

During the northern hemisphere winter season the higher HF bands of 10-20 meters (11-19 meters) close sooner due to less sun light illuminating the ionosphere than in the southern hemisphere. But the maximum usable frequency (MUF) is higher than in the southern hemisphere as the F layer of the ionosphere is lower in height and more concentrated.

Southern Hemisphere Radio Wave Propagation Forecast-

3150-3400, 3500-4100, 4750-5050, 5700-6300- fair at night and poor at day,

6900-7800, 9200-9995, 10000-10150, 11500-12200 kHz- fair at night and fair at day,

13570-13850, 14000-14350, 15005-15900, 17450-17950, 18068-18168, kHz- 

fair at night and poor to fair at day,

21000-21850 kHz- poor at night and fair at day,

24890-24990, 25600-26100 kHz- poor at night and poor at day,

28000-29700 kHz- very poor at night and poor at day.

Excellent- S9+10 or >

Very Good- S9 +1-9

Good- S8-9

Fair- S4-7

Poor- S1-3

Very Poor- S0

Keep in mind that almost daily during the southern hemisphere summer season you will find that the 10 (11) meter bands will open via short north-south and east-west propagation paths via sporadic E (Es). Also when multiple sporadic E (Es) clouds form and line up favorably much longer propagation paths open up on east-west paths. And last but not least north-south propagation paths occur across the equator via trans equatorial propagation (TEP).

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This HF Radio wave propagation forecast is produced based on the SIGINT_CAP HF radio wave propagation prediction software. I wrote it beginning in the late 1980’s but I’m sorry to say that it can’t be distributed to the general public.

And though this HF radio wave propagation forecast is produced based on the SIGINT_CAP, I do check the actual band conditions at my location in the USA and tweak the forecast manually where and when necessary. I also check global HF radio wave propagation conditions via remoted radio receivers around on every continent of the globe and tweak the forecast manually if and when necessary.

The hamateur radio JT65A mode RF signal levels received are based on 5 watts and ½ wave dipole up at 40 feet.

The hamateur radio PSK31 mode RF signal levels received are based on 25 watts and ½ wave dipole up at 40 feet.

The hamateur radio CW mode RF signal levels received are based on 50 watts and ½ wave dipole up at 40 feet.

The hamateur radio SSB RF mode signal levels received are based on 100 watts and ½ wave dipole up at 40 feet.

The HF shortwave broadcast band AM Mode RF signal levels are based on 100,000 watts (100 kw) and a typical high gain VOA type curtain array antenna.

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Please keep in mind that this is a relatively simplified HF radio wave 

propagation forecast, so as to keep it easily understandable and applicable by the average radio enthusiast.

Globally HF radio wave propagation conditions are most evenly balanced 

during the fall and spring equinoxes and most diametrically opposed during 

the summer and winter solstices.

Conditions change daily, weekly, monthly, yearly and by decade, as the 

sun rises and sets at different times and at different angles from the 

ecliptic, as well as by radio wave frequency. This is due to changes in the 

maximum usable frequency (MUF), lowest usable frequency (LUF) and F layer 

critical frequency (FoF2).

The D and E layers also come into play through RF radio wave signal 

absorption and refraction. And then there is sporadic E (Es) radio wave 

propagation that can really throw a wrench into the gears so to speak.

Things like sporadic E (Es) radio wave propagation and lightning storm 

static can impact HF radio wave propagation in an unpredictable manner and 

mostly bad.

Ongoing solar, space and geomagnetic weather goings on also impact HF radio 

wave propagation conditions in a negative manner.

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GENERAL GUIDELINES CONCERNING CORRELATION OF PROPAGATION INDICES TO ACTUAL HF PROPAGATION CONDITIONS-

NOTE!!! The propagation indices "interpretations" are my personal 

intellectual property. Therefore the radio wave propagation indices 

allowed without permission in advance as long as proper credit is given.

All 14 of the following indices have to occur as described below in order to 

see the best global high frequency radio wave propagation possible,

something that happens rarely.

1.) Dropping geomagnetic field indices numbers are better, Kp of 0 best.

2.) A daily sunspot number of 150 or higher, 200 or higher best.

3.) A daily sunspot number of greater than 100 for routine stable formation 

of the E Valley/F Layer ducting mechanism.

4.) Previous 24 hour Ap index under 10, fewer than 7 for several days 

consecutively are best.

5.) Previous 3 hours Kp index fewer than 3 for mid latitude paths, fewer 

than 2 for high latitude paths, 0 for several days consecutively is best.

6.) Energetic protons no greater than 10 MeV (10+0).

7.) Background x-ray flux levels greater than B1 for several days 

consecutively, greater than C1 best.

8.) No current STRATWARM alert.

9.) Interplanetary magnetic field (IMF) Bz with a (positive number) sign, 

indicates a lesser chance of high latitude path aurora 

absorption/unpredictable refraction or scattering of medium frequency RF 

signals, when the Kp is above 3.

10.) A -10 or better towards a positive number Dst index during the recovery 

time after a geomagnetic storm, as related to the equatorial ring current. A 

positive number is best.

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Standard Disclaimer-

Note! I use error prone RAW public domain data from the NOAA Space 

Environment Center, other U.S. government entities and educational 

institutions, to produce this daily HF radio wave propagation 

forecast. This data is gathered and made public by the U.S. Government using 

taxpayer $$$ (including mine).

However this daily HF propagation forecast that I produce from the RAW public domain data is my personal intellectual property. Therefore this daily HF radio wave propagation forecast contained herein is copyrighted © 1988-2017 by Thomas F. Giella, W4HM.

Feel free without prior permission to redistribute this daily HF radio wave propagation forecast, as long as you redistribute it in its entirety and 

give me credit for it.

Also HF radio wave propagation forecasting is still an inexact 

science. The forecasts are not official but for educational and hobby 

related purposes only and are subject to human error and acts of God, 

therefore no guarantee or warranty implied. 