[W4HM Spaceweather] W4HM Daily HF Radio Wave Propagation Forecast #241

Tue Aug 29 16:18:35 EDT 2017

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#241 Issued on Tuesday August 29, 2017 at 2000 UTC

Global Daily HF Radio Wave Propagation Forecast- 

HF radio wave propagation condition trend- steady state, which means neither improving nor deteriorating.

Northern Hemisphere Radio Wave Propagation Forecast-

80-60 (75-60) meters- poor to fair at night and very poor at day, 

40-30 (41-25) meters- fair to good at night and poor at day,

20-17 (22-15) meters- fair to good at night and poor to fair at day, 

15 (13) meters- very poor at night and poor to fair at day,

12(11) meters- very poor at night and poor at day.

10 (11) meters- very poor at night and very poor at day.

Keep in mind that almost daily during the northern 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 can open up on east-west paths. And last but not least equidistant north-south propagation paths occur across the equator via trans equatorial propagation (TEP).

Southern Hemisphere Radio Wave Propagation Forecast-

80-60 (75-60) meters- good at night and poor at day, 

40-30 (41-25) meters- good at night and fair at day,

20-17 (22-15) meters- very poor at night and good at day, 

15 (13) meters- very poor at night and fair to good at day,

12 (11) meters- very poor at night and fair at day.

10 (11) meters- very poor at night and poor at day.

During the southern 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 northern hemisphere. But the maximum useable frequency (MUF) is higher than in the northern hemisphere as the F layer of the ionosphere is lower in height and is more dense.

Received RF signal strength scale-

Very Good- +1 over S9 Or Greater

Good- S7-9

Fair- S4-6

Poor- S1-3

Very Poor- S0

Meter Band Equivalents

Ham & SWL

160->   90

80->     75

60->     60

40->     49, 41

30->     31, 25

20->     22, 19

17->    16, 15

15->    13

12,10-> 11

We are now firmly in summer/winter solstice type of HF radio wave propagation conditions.

This means generally poor HF radio wave propagation conditions in the northern hemisphere especially at day and generally good HF radio wave propagation conditions in the southern hemisphere especially at day.

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 solstice.

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).

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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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Solar, Space & Geomagnetic Weather Conditions On

Monday August 28, 2017-

Solar activity was high.

Earth's geomagnetic field was at a quiet level.

The three daily solar flux index (SFI) numbers were 83.7 81.6 82.6.                     

The official daily sunspot number (SSN) was 17.

In 2017 officially there were 56 days with a daily sunspot number (SSN) of 

0.

Considering that solar minimum won't occur for approximately 2 more years, 

+/- 1 year, daily SSN's of 0 are occurring unusually early.

In 2016 officially there were 32 days with a daily sunspot number (SSN) of 

0. 

As we move forward towards the next solar minimum between solar cycle #24 

and #25 the number of days with a 0 daily SSN will steadily increase. 

Eventually every day for many, many, many months will see a 0, the big goose 

egg.

In 2008 I forecasted solar cycle 24 to be the weakest in the past 100 years 

and that forecast verified. I also forecasted that solar cycle 25 would be 

virtually nonexistent, similar to the Dalton type solar minimum that 

occurred in the early 1800's. 

Other than sunspot magnetic polarity it will probably be very difficult to determine when solar cycle 24 ended and solar cycle 25 began.

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Officially there were 3 earth facing sun spot groups (SSG).

Sunspot group (SSG) #12672 was located near N06W36 with a complex beta magnetic signature. 

It was capable of producing a small in size C class solar flare and an isolated moderate in size M class solar flare.

Newly emerged sunspot group (SSG) #12673 was located near S08E78 with a simple alpha magnetic signature. 

It was capable of producing a small in size C class solar flare.

Newly emerged sunspot group (SSG) #12674 was located near N08E78 with a complex beta magnetic signature. 

It was capable of producing a small in size C class solar flare and an isolated moderate in size M class solar flare.

There was 1 unofficial and as of yet unnumbered earth facing sunspot group (SSG) near

N10E01.

There were 3 small in size C class solar flares,

C2.8,

C1.0,

C1.0.

There was 1 “partially” earth aimed (geoeffective) coronal mass ejection (CME). It could impact earth’s geomagnetic field in a minor negative manner on approximately Friday September 1, 2017.

No directly earth aimed (geoeffective) coronal mass ejection (CME) related high and mid latitude energetic proton storm >10 MeV (10+0) occurred (polar cap absorption).

No directly earth aimed (geoeffective) solar flare related x-ray day side solar fade out (SFO) occurred.

No directly earth aimed (geoeffective) collapsing magnetic filament eruption occurred.

The 24 hour period 3 hour interval planetary K index (Kp) was at quiet geomagnetic conditions of 

1 1 1 1 0 0 0 1.

The 24 hour period 3 hour interval Boulder, CO K index was at quiet geomagnetic conditions of 

1 1 1 1 1 2 0 1.

The K(p) geomagnetic indices are-

0-2- quiet

3- unsettled

4- active

5- minor geomagnetic storming

6- moderate

7- strong

8- severe

9- extreme

10- our atmosphere just got cooked off like on Mars and we are all dead.

The 24 hour period maximum and minimum planetary A index (Ap) ranged between

4 and 0,

which was at quiet geomagnetic conditions.

The Ap geomagnetic indices are-

0-7- quiet

8-15 unsettled

16-29- active

30-49- minor geomagnetic storm

50-99- major

100-400- severe

>401- our atmosphere just got cooked off like on Mars and we are all dead.

The 24 hour period averaged energetic proton flux was at a background level below 10 MeV.

The 24 hour period averaged background x-ray flux was at C2.84.

The 24 hour period averaged vertical component (Bz) of earth's geomagnetic magnetic field was at

-4.40 nT south.

The 24 hour period maximum and minimum disturbance storm time index (Dst) ranged between

 -29 and +1 nT. 

The 24 hour period maximum and minimum solar wind speed ranged between

 358 and 276 km/s. The 276 reading is the slowest velocity in quite a long time. We will see more and more of these slow solar wind speeds as we move further into deep solar minimum. There was a recurrent very large in size directly (geoeffective) earth facing trans equatorial coronal hole (CH) #822 (#818).  In approximately 2 days its high speed solar wind stream (HSS) will connect to earth’s geomagnetic field and begin impacting it in a negative manner in the form of possible minor (Kp-5) geomagnetic storming conditions.  

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.

11.) Rising positive T index number. The T Index tracks with the F2 layer 

critical frequency (foF2) and sunspot number (SSN) and indicates the 

capability of the F2 layer to refract RF signals.

12.) Galactic cosmic rays decrease to -3 units below zero and trending 

towards zero.

13.) Energetic electron flux levels no greater than 2 MeV (2+0).

14. A solar wind speed of less than 300 km/s for several days consecutively.

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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 my comprehensive HF radio wave propagation 

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

taxpayer $$$ (including mine).

However the solar, space and geomagnetic discussions as well as the HF propagation forecast that I produce from the RAW public domain 

data is my personal intellectual property. Therefore the solar, space and geomagnetic weather discussions and HF radio wave 

propagation forecast contained herein is copyrighted © 1988-2017 by Thomas 

F. Giella, W4HM.

Feel free without advanced permission to redistribute this "not for profit" 

solar, space and geomagnetic weather discussion and HF radio wave propagation forecast, as long as you redistribute it in its entirety and 

give me credit for it.

Also solar, space and geomagnetic weather 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. 