[RSM] W3LPL forecast Tue-Wed April 6-7

[Art Boyars]

From: donovanf at erols.com
To: PVRC Reflector <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Tue, 6 Apr 2021 00:31:06 -0400 (EDT)
Subject: [PVRC] Normal but near solar minimum propagation through at least
Wednesday

Long distance propagation forecast for Tuesday and Wednesday, April 6-7


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. Auroral oval and polar propagation is likely to be

mostly normal with possible below normal intervals through

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 70 through Wednesday.

There is only one small sunspot region on the visible disk with one

very tiny sunspot having no effect on HF propagation.



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 at about 0100Z is likely to be

mostly normal through Wednesday. 80 and 40 meter short path

propagation from North America to east Asia after 0900Z is likely

to be mostly normal with possible below normal intervals through

Wednesday.



30 meter auroral oval and polar propagation is likely to be mostly

normal with possible below normal intervals through 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 only one very tiny sunspot on the visible disk.



20 meter daytime northern auroral oval and polar propagation is

likely to be mostly normal with possible below normal intervals

through 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 only one very

tiny sunspot 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 only one very tiny

sunspot 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 relatively

infrequent through at least late 2021. 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 an

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 slightly enhanced through Wednesday

because of weak coronal hole high speed stream influence. CMEs,

geomagnetic storms and solar flares strong enough to affect

HF propagation are not likely through Wednesday.



Mid latitude northern hemisphere sunset is now 16 minutes later

and daylength is 43 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 begins in the

northern polar region at sunrise Tuesday and ends at the next sunset

on September 5th, significantly 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


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