[RSM] W3LPL forecast Mon-Tue April 12-13

[Art Boyars]

From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Mon, 12 Apr 2021 00:22:20 -0400 (EDT)
Subject: [PVRC] Near solar minimum propagation conditions likely to persist
through Tuesday

Long distance propagation forecast for Monday and Tuesday, April 12-13


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

Tuesday. Propagation through the auroral ovals and across polar

regions is likely to be mostly normal through Tuesday



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 72 through Tuesday.

There are no sunspots on the visible disk.



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 Tuesday. 80 and 40 meter

short path propagation to south Asia is likely to be mostly normal

at about 0100Z through Tuesday. 80 and 40 meter short path

propagation from North America to east Asia after about 0900Z

is likely to be mostly normal through Tuesday.



30 meter propagation through the auroral ovals and across polar

regions is likely to be mostly normal through Tuesday. 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 no

sunspots on the visible disk.



20 meter daytime propagation through the auroral ovals and across

polar regions is likely to be mostly normal through Tuesday. 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 no sunspots on the visible disk.



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 no sunspots on the visible disk.

12 and 10 meter daytime long distance propagation is likely to be

unreliable and 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 near background levels through Tuesday.

Earth directed coronal hole high speed streams, CMEs,

geomagnetic storms and solar flares strong enough to affect HF

propagation are not likely through Tuesday.



Mid latitude northern hemisphere sunset is now 22 minutes later and

daylength is 58 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