[RSM] W3LPL forecast Tues/25 thru Wed/26

Tue May 25 01:53:28 EDT 2021

From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Tue, 25 May 2021 00:28:29 -0400 (EDT)
Subject: [PVRC] Normal propagation through mid-day Tuesday then degrading
to mostly below normal

Long distance propagation forecast for Tuesday and Wednesday May 25-26

My propagation forecast derived from today's NOAA/SWPC

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

Low latitude propagation is likely to be normal then degrading

to mostly normal from mid-day Tuesday through Wednesday.

Brief MUF enhancements are possible on low latitude paths

after mid-day Tuesday.

Mid-latitude propagation is likely to be normal then degrading

to mostly below normal from mid-day Tuesday through Wednesday.

Brief MUF enhancements are possible on mid-latitude paths after

mid-day Tuesday.

Propagation through the auroral ovals and polar regions is likely

to be mostly normal then degrading to below normal from mid-day

Tuesday through mid-day 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 75 through Wednesday.

Decaying active region 2824 has eight small sunspots having a

minor effect on HF propagation. Active region 2825 has only

one tiny sunspot having no significant effect on HF propagation.

160 and 80 meter short path propagation from North America to

VK/ZL and the south Pacific is likely to be normal through Wednesday.

40 meter short path propagation to south Asia is likely to be

below normal at about 0015Z Wednesday. 40 meter short path

propagation from North America to east Asia after about 0930Z

is likely to be mostly normal on Tuesday and below normal on

Wednesday.

30 meter propagation through the auroral ovals and polar

regions is likely to be mostly normal then degrading to

below normal from mid-day Tuesday through mid-day 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 night time propagation

in the northern hemisphere is likely to improve slightly due to

minor sunspot influence and longer daylight duration.

20 meter daytime and evening propagation through the

auroral ovals and polar regions is likely to be mostly normal

then degrading to below normal from mid-day Tuesday through

Wednesday. 20 meter northern transpolar propagation within

a few hours of sunrise and sunset will steadily improve with

gradually increasing electron density in the polar F2 region

through June. 20 meter night time long distance propagation

in the northern hemisphere is likely to improve slightly due to

minor sunspot influence and longer daylight duration.

17 and 15 meter daytime long distance propagation in the

northern hemisphere is likely to improve slightly due to

minor sunspot influence and longer daylight duration.

15, 12 and 10 meter daytime long distance propagation

is likely to be sporadically enhanced by sporadic-E

propagation through July.

Geomagnetic disturbances *caused by coronal hole high speed*

*streams* are likely to remain mostly brief, minor and somewhat

less frequent through at least late 2021. The north-south (Bz)

component of the IMF plays a *crucial but unpredictable role*

in triggering all geomagnetic storms. Brief minor to moderate

geomagnetic storms may be gradually triggered when Bz

persists in a southward orientation (-Bz) with enhanced IMF

field strength for several hours *coincident with* the effects of

an earth directed *coronal hole high speed stream*. More frequent,

longer duration, minor to severe geomagnetic storms may be

triggered *suddenly* *and unpredictably *when Bz persists in a

southward orientation (-Bz) with enhanced IMF field strength

for several hours or more *coincident with* the effects of an earth

directed CME.

IMF field strength, solar wind speed near earth and geomagnetic

activity are likely to be at background levels through mid-day

Tuesday when an earth directed CME may trigger a minor

geomagnetic storm later in the day and possible minor to

moderate geomagnetic storms through mid-day Wednesday.

Earth directed coronal high speed streams are not likely through

Wednesday. There is a chance that M-Class solar flares may

briefly degrade HF propagation on the sun-facing side of the earth through
Wednesday.

Mid latitude northern hemisphere sunset is now 62 minutes

later and daylength is 145 minutes longer than it was on the

March 20th. Daylength is increasing by just over one minute

per day which is slowly lengthening the duration of commo

 daylight between distant locations in the northern hemisphere.

The elevation angle of the midnight sun in the northern polar

region is increasing about three degrees per week, slowly

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 1700Z, 2000Z and 2300Z 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