[RSM] W3LPL forecast Fri/21 thru Sun/23

[Art Boyars]

From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Fri, 21 May 2021 00:50:35 -0400 (EDT)
Subject: [PVRC] Mostly normal propagation with possible below normal
periods on Friday, gradually improving to normal on Sunday

Long distance propagation forecast for Friday through Sunday May 21-23


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 through Sunday.



Mid-latitude propagation is likely to be mostly normal on Friday

and Saturday gradually improving to normal on Sunday.



Propagation through the auroral ovals and polar regions is likely

to be mostly normal with possible below normal periods on Friday

improving to mostly normal on Saturday and gradually improving

to normal on Sunday.



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 Sunday.

One active region on the visible disk with three small sunspots is

having a minimal effect on HF propagation. A new active region

may rotate onto the visible disk by Sunday.



160 and 80 meter short path propagation from North America to

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

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

mostly normal at about 0015Z through Sunday. 40 meter short path

propagation from North America to east Asia after about 0930Z

is likely to be mostly normal with possible below normal periods

on Friday improving to mostly normal on Saturday and gradually

improving to normal on Sunday..



30 meter propagation through the auroral ovals and polar regions

is likely to be mostly normal with possible below normal periods

on Friday improving to mostly normal on Saturday and gradually

improving to normal on Sunday. 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 with possible below

normal periods on Friday improving to mostly normal on Saturday

and gradually improving to normal on Sunday. 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. 12 and 10 meter daytime long distance

propagation is likely to be mostly 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 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* 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 moderately enhanced by coronal hole high speed stream

effects on Friday, improving the nominal levels on Saturday and

gradually improving to background levels on Sunday. Geomagnetic

storms and earth directed CMEs and solar flares strong enough

to affect HF propagation are not likely through Sunday.



Mid latitude northern hemisphere sunset is now 60 minutes later and

daylength is 141 minutes longer than it was on the March 20th.

Daylength is increasing by nearly two minutes per day which

is steadily lengthening the duration of common 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, steadily 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