[W4HM Spaceweather] W4HM Daily HF Radio Wave Propagation Forecast #144

Wed May 24 10:59:22 EDT 2017

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#144 Issued on Wednesday May 24, 2017 at 1230 UTC

We are now moving into the 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 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).

Global Daily HF Radio Wave Propagation Forecast-

HAMATEUR & SW BROADCAST HF BANDS-

NORTHERN HEMISPHERE RADIO WAVE PROPAGATION-

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

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

20-17 (22-16) meters- fair at night and fair at day, 

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

12-10 (11) meters- very poor at night and very poor at day.

SOUTHERN HEMISPHERE RADIO WAVE PROPAGATION-

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

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

20-17 (22-16) meters- very poor at night and fair at day, 

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

12-10 (11) meters- very poor at night and very poor at day.

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

This HF Radio wave propagation forecast is based on the W4HM_Cap HF radio wave propagation prediction software.

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 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

Tuesday May 23, 2017-

Solar activity was low.

Earth's geomagnetic field was at an unsettled level.

The three daily solar flux index (SFI) numbers were 75.4 76.0 75.4.

The official daily sunspot number (SSN) was 47. 

In 2017 officially there were 37 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 now unusually early.

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

0. Considering that solar minimum won't occur for approximately three more 

years, seeing daily SSN's of 0 occurring now is unusually early.

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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There were 4 newly risen or emerged official sunspot groups.

Sunspot group #12656 was located near N12W47 with a magnetically simple alpha magnetic signature.

Sunspot group #12658 was located near S06W34 with a magnetically simple alpha magnetic signature.

Sunspot group #12659 was located near N13W05 with a magnetically simple beta magnetic signature.

Sunspot group #12660 was located near S10W25 with a magnetically simple beta magnetic signature.

There were 3 unofficial and as of yet unnumbered earth facing sunspot group located near

S09E09,

N15W56,

S32W09.

No earth facing C class or larger solar flares occurred.

No day side high latitude solar fade outs (SFO) occurred. 

The solar fade outs (SFO) are also called polar cap absorption (PCA) mostly caused by energetic protons striking earth’s geomagnetic field and increasing RF signal absorption in the D layer at high latitudes.

An earth facing and partially directed (geoeffective) coronal mass ejection (CME) occurred. It may impact earth’s geomagnetic field in a negative manner on approximately Friday May 26, 2017.

No earth directed collapsing magnetic filament eruptions occurred. 

The twenty four hour period 3 hour interval planetary K index (Kp) was at unsettled to quiet geomagnetic conditions of 

1 3 1 1 2 1 2 2.

The Kp 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

15 and 4,

which was at unsettled to 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 B4.45.

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

-2.30 nT south.

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

 -18 and -2 nT. 

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

557 and 449 km/s  and was directly connected by a high speed solar wind stream (HSS) to trans equatorial coronal hole (CH) #804 (#802).  There was a new earth facing northern hemisphere coronal hole #805. It became directly earth facing (geoeffective) on Tuesday May 23, 2017. However as it’s located at a high latitude position on the earth facing side of the sun, it probably won’t impact earth’s geomagnetic field in a negative way.

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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.

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. 