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Home > Propagazione > W4HM Daily HF Radio Wave Propagation Forecast #95

W4HM Daily HF Radio Wave Propagation Forecast #95

For my hamateur radio and SWL friends around the globe:

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solar, space and geomagnetic weather observation, discussion and HF radio
wave propagation forecast, as long as you redistribute it in its entirety
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#95 Issued on Thursday April 20, 2017 at 1130 UTC

Global Daily HF Radio Wave Propagation Forecast-

HAMATEUR & SW BROADCAST HF BANDS:

Global generalized HF radio wave propagation conditions are

poor to fair on 10-80 (11-75) meters

NORTHERN 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.

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

Please keep in mind that this is a relatively simplified HF radio wave
propagation forecast, so as to keep it easily understandable 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 also 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

Wednesday April 19, 2017-

Solar activity was moderate.

Earth’s geomagnetic field was at storming level.

The three daily solar flux index (SFI) numbers were 81.7 80.9 80.5.

The official daily sunspot number (SSN) was 14.

In 2017 officially there were 30 days with a daily sunspot number (SSN) of
0.

Considering that solar minimum won’t occur for approximately 2 more years,
+/- 1 year, observations daily SSN’s of 0 occurring now is unusually early.

Recurrent sunspot group #12651 (#12644) was located near N11E58 with a more
magnetically complex beta-gamma magnetic signature capable of producing
medium size M class solar flares.

Unofficially there were 3 earth facing but as of yet unnumbered sunspot
groups. They were located near

N08E13,
N11W41,
N12E73.

One earth facing C class or larger solar flare occurred. It was a

C2.0.

———————————————————————————————

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 fore casted solar cycle 24 to be the weakest in the past 100 years
and that forecast verified. I also fore casted that solar cycle 25 would be
virtually nonexistent, similar to the Dalton type solar minimum that
occurred in the early 1800’s. It will probably be very difficult to
determine when solar cycle 24 ended and solar cycle 25 began.

———————————————————————————————

No (geoeffective) directly earth facing coronal mass ejections (CME)
occurred.

But an earth facing coronal mass ejection (CME) was visible on SOHO/LASCO
imagery but the plasma cloud was east directed.

http://www.spaceweather.com/images2017/19apr17/cme_c3_anim.gif?PHPSESSID=dcs1vapmm0niauaqin4tml8c45

No earth directed collapsing magnetic filament eruptions occurred.

No earth directed day side radio black outs occurred.

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

3 4 3 1 1 2 3 3.

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

32 and 3,

which was at minor geomagnetic storming conditions 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 daily averaged background x-ray flux was at B8.06.

The daily averaged vertical component (Bz) of earth’s magnetic field was at
-3.37 nT south.

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

+11 and 42 nT.

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

517 and 341 km/s

and was directly attached by a high speed solar wind stream to (CH) coronal
hole #801.

There was a southern hemisphere earth facing (CH) coronal hole #801. It
produced minor (Kp-5) geomagnetic storming during its last trip across the
earth facing side of the sun.

There was a recurrent southern hemisphere (geoeffective) directly earth
facing (CH) coronal hole #802 (#798). It produced moderate (Kp-6)
geomagnetic storming during its last trip across the earth facing side of
the sun.
————————————————————————————–

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
interpretations contained herein is copyrighted © 1988-2017 by Thomas F.
Giella, W4HM, all rights reserved. Reproduction of information herein is
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 propagation forecast that I produce from the RAW public domain
data is my personal intellectual property. Therefore this radio wave
propagation forecast contained herein is copyrighted © 1988-2017 by Thomas
F. Giella, W4HM.

Feel free to redistribute this solar, space and geomagnetic weather
discussion and HF radio wave propagation forecast, as long as you
redistribute it in it’s 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.

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