[RSM] W3LPL forecast Wed/19 - Thur/20

[Art Boyars]

I've been offline for a couple of days.  Now resuming my forwarding of
Frank's forecasts.

73, Art K3KU/VE4VTR
======================
From: donovanf at erols.com
To: PVRC <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Wed, 19 May 2021 01:28:30 -0400 (EDT)
Subject: [PVRC] Mostly normal to below normal propagation through Thursday

Long distance propagation forecast for Wednesday and Thursday May 19-20


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 Thursday.



Mid-latitude propagation in likely to be mostly normal through

Thursday.



Propagation through the auroral ovals and polar regions is likely

to be mostly below normal through Thursday.



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 Thursday.

Two active regions on the visible disk with four small sunspots are

having a minimal 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 Thursday.

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

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

propagation from North America to east Asia after about 0930Z

is likely to be mostly below normal through Thursday.



30 meter propagation through the auroral ovals and polar regions

is likely to be mostly below normal through Thursday. 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 below normal through

Thursday. 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 stream*

 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 the arrival of a

coronal hole high speed stream and possible arrival of a weak CME

on Wednesday and continuing into Thursday. There is a possibility

of an isolated weak geomagnetic storm on Wednesday. Solar flares

strong enough to affect HF propagation are not likely through Thursday.



Mid latitude northern hemisphere sunset is now 57 minutes later

and daylength is 138 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