[RSM] W3LPL forecast Tue-Wed April 13-14

[Art Boyars]

From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Tue, 13 Apr 2021 00:11:05 -0400 (EDT)
Subject: [PVRC] Normal propagation likely through about 1800Z Wednesday

Long distance propagation forecast for Tuesday and Wednesday, April 13-14


My propagation forecast derived from today's NOAA/SWPC web

pages is published five days a week (M-F) in the Daily DX.



Low and mid-latitude propagation is likely to be normal through

Wednesday. Propagation through the auroral ovals and across

polar regions is likely to be normal through about 1800Z

Wednesday then mostly below normal late Wednesday.



Click *here* <https://services.swpc.noaa.gov/images/planetary-k-index.gif>
for today’s
latest planetary Kp Index, updated every three hours.

Click *here* <http://www.hamqsl.com/solar.html> for N0NBH’s current HF Band
Conditions, updated regularly.



The solar flux index (SFI) is likely to be about 78 through

Wednesday. A small sunspot region is slowly developing

and currently has six tiny sunspots,



We are in the most disturbed weeks of the March-April

geomagnetic storm season when the earth is passing

through the part of the interplanetary magnetic field (IMF)

with the most frequent, longest duration southward oriented

IMF. Approximately twice as many brief minor and moderate

geomagnetic storms occur during March and April compared

to the quieter IMF during June and July. Brief minor to

moderate geomagnetic storms may be triggered with little

warning when the IMF rotates to a southward orientation

and persists for several hours *coincident with* the effects of

earth directed coronal hole high speed streams and coronal

mass ejection (CME) enhancements in the solar wind.



160 and 80 meter short path propagation from North America to

VK/ZL is likely to be normal through Wednesday. 80 and 40 meter

short path propagation to south Asia is likely to be normal at about

0100Z through Wednesday. 80 and 40 meter short path propagation

from North America to east Asia after about 0900Z is likely to be

normal through Wednesday.



30 meter propagation through the auroral ovals and across polar

regions is likely to be normal through about 1800Z Wednesday then

mostly below normal late Wednesday. 30 meter propagation is always

significantly degraded within a few hours of local noon because of

E-region blanketing of long distance F2 propagation. 30 meter long

distance propagation is unreliable during most of the night in the

northern hemisphere because of insufficient residual night time

F region electron density due to six tiny sunspots on the visible disk

having little effect on HF propagation.



20 meter daytime propagation through the auroral ovals and

across polar regions is likely to be normal through about

1800Z Wednesday then mostly below normal late Wednesday.

20 meter northern trans-polar propagation within a few hours

of sunrise and sunset will steadily improve with gradually

increasing electron density in the polar F2 region through June.

Night time 20 meter long distance propagation in the northern

hemisphere continues to be unreliable because of insufficient

residual F region electron density due to six tiny sunspots

on the visible disk having little effect on HF propagation.



17 and 15 meter daytime long distance propagation in the northern

hemisphere continues to be shorter in duration because of

insufficient F2 region electron density due to six tiny sunspots

on the visible disk having little effect on HF propagation. 12 and 10

meter daytime long distance propagation is likely to be unreliable

mostly limited to propagation from North America to Southern

Africa, South Atlantic, South America and South Pacific regions.



Geomagnetic disturbances *caused by coronal hole high speed*

*streams *are likely to remain mostly brief, minor and less frequent

through at least late 2021. The north-south (Bz) component of the

IMF plays a crucial role in triggering brief minor to moderate

geomagnetic storms when it persists in a southward orientation

(-Bz) with enhanced field strength for several hours *coincident with*

the effects of earth directed coronal hole high speed stream or

CME enhancements in the solar wind.



IMF field strength, solar wind speed near earth and geomagnetic

activity are likely to be at background levels through about 1800Z

Wednesday then slightly elevated  late Wednesday due to weak

coronal hole high speed stream effects. Earth directed CMEs,

geomagnetic storms and solar flares strong enough to affect

HF propagation are not likely through Wednesday.



Mid latitude northern hemisphere sunset is now 23 minutes later

and daylength is 60 minutes longer than it was on the March 20th.

Daylength is increasing by two minutes per day which is steadily

lengthening the duration of common daylight between distant

locations in the northern hemisphere. Midnight sun in the northern

polar region is gradually improving 20 meter northern trans-polar

propagation through June.



Click *here* <https://www.spaceweather.gc.ca/solarflux/sx-4-en.php> for today’s
Penticton 10.7 cm solar flux index updated at 1800Z, 2000Z and 2200Z daily.

Click *here*
<https://spaceweather.gfz-potsdam.de/fileadmin/ruggero/Kp_forecast/forecast_figures/KP_FORECAST_CURRENT.png>
for today’s
three-day GFZ Planetary K Index forecast updated every three hours.

Click *here* <http://sidc.oma.be/products/meu/> for today's SIDC Daily
Bulletin on Solar and Geomagnetic Activity updated at 1230Z daily.

Click *here* <https://www.swpc.noaa.gov/products/forecast-discussion>
for today's
SWPC Solar Activity Forecast Discussion updated at 0030Z and 1230Z daily.

Click *here* <https://www.sws.bom.gov.au/Space_Weather/1/1> for today's
Australian Space Forecast Centre Summary and Forecast updated at 2330Z
daily.



Perhaps the most useful HF propagation pages for DXers can be found at:

http://dx.qsl.net/propagation and http://www.solarham.net