[RSM] W3LPL forecast Mon-Tue Apr 5-6

[Art Boyars]

From: donovanf at erols.com
To: PVRC Reflector <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Mon, 5 Apr 2021 01:24:01 -0400 (EDT)
Subject: [PVRC] Mostly normal propagation likely through Tuesday

Long distance propagation forecast for Monday and Tuesday, April 5-6

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. Auroral oval and polar propagation is likely to be mostly

normal with possible below normal intervals 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 is only one small sunspot region on the visible disk with one

tiny sunspot having no affect 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 Tuesday. 80 and 40

meter short path propagation to south Asia at about 0100Z

is likely to be mostly normal through Tuesday. 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 Tuesday.



40 and 30 meter long path propagation from North America

to southeast Asia at about 2315Z is likely to be mostly

normal through Tuesday.



30 meter auroral oval and polar propagation is likely to be

mostly normal with possible below normal intervals 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 only one 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 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 only one 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 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 weakly enhanced through Tuesday

because of coronal hole high speed stream influence. CMEs,

geomagnetic storms and solar flares strong enough to affect

HF propagation are not likely through Tuesday.



Mid latitude northern hemisphere sunset is now 15 minutes later

and daylength is 40 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. Daylength in the north polar

region is approximately 22 hours and increasing by 30 minutes

per day until five months of midnight sun begins with the last

sunrise on April 6, 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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