[RSM] W3LPL: Mostly normal but... thru Sunday/22

[Art Boyars]

From: donovanf at erols.com
To: PVRC Submissions <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Fri, 20 Aug 2021 02:00:42 -0400 (EDT)
Subject: [PVRC] Mostly normal but near solar minimum propagation is likely
to continue through Sunday August 22th

My propagation forecast derived from today's NOAA/SWPC web pages is
published five days a week (M-F) in the Daily DX.



Propagation crossing low and mid latitudes is likely to be normal but near
solar minimum conditions through Sunday.



Propagation crossing the auroral ovals and polar regions is likely to be
mostly normal but near solar minimum conditions through Sunday.



Click here for today’s latest planetary Kp Index, updated every three hours.

Click here for N0NBH’s current HF Band Conditions, updated regularly.


We are transitioning into more frequent mildly active geomagnetic
activity during late August. The more geomagnetically active autumn
equinox season begins in September and runs through late October.

Sporadic-E propagation will be shorter in duration and more unreliable at
mid-latitudes in the northern hemisphere through late August making long
distance propagation up to about 8,000 km intermittent and unreliable in
the 17, 15, 12 and 10 meter bands from a few hours after sunrise until a
few hours after sunset.

The solar flux index (SFI) is likely to be 75 or less through Sunday.

The sun’s visible disk has one small active region with four tiny sunspots
having little effect on propagation.

https://sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_0171.jpg

160 and 80 meter 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 at about 0015Z is likely to be mostly normal
through Sunday. 40 meter short path propagation from North America to east
Asia after about 0930Z is likely to be mostly normal through Sunday.

30 meter propagation through the auroral ovals and polar regions is likely
to be mostly normal through 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 long distance propagation in the northern hemisphere is
likely to less reliable due to decreased ionizing solar radiation in the
northern high latitude regions caused by lower solar elevation angles and
lengthening nights with no source of ionizing solar radiation.

20 meter daytime and evening propagation through the auroral ovals and
polar regions is likely to be mostly normal through Sunday. 20 meter
northern transpolar propagation within a few hours of sunrise and sunset is
less reliable and shorter in duration due to decreased ionizing solar
radiation in the northern high latitude regions caused by lower solar
elevation angles and lengthening nights with no source of ionizing solar
radiation. 20 meter long distance propagation is significantly degraded
from
mid-morning through late afternoon at mid and especially low latitudes in
the northern hemisphere by F1 region mid-day blanketing of low angle long
distance propagation through late August. 20 meter late afternoon,
nighttime and early morning long distance propagation in the northern
hemisphere is likely to be significantly shorter in duration due to
decreased ionizing solar radiation in the northern high latitude regions
caused by declining elevation angles and lengthening nights with no
source of ionizing solar radiation.

17 and 15 meter daytime long distance propagation in the
northern hemisphere is likely to be shorter in duration due to decreased
ionizing solar radiation in the northern high latitude regions caused
by lower solar elevation angles and lengthening nights with no source of
ionizing solar radiation. 17, 15, 12 and 10 meter sporadic-E propagation up
to 8,000 km is likely to be intermittent, short duration and unreliable
from a few hours after sunrise until a few hours after sunset through late
August.

Geomagnetic disturbances caused by coronal hole high speed stream  effects
are likely to remain mostly brief, minor and somewhat less
frequent through at least late 2021. The southward oriented (-Bz)
component of the interplanetary magnetic field (IMF) plays a crucial but
unpredictable role in triggering all geomagnetic storms. Brief minor to
moderate geomagnetic storms may be gradually triggered when the IMF
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 the IMF
persists in a southward orientation (-Bz) with enhanced IMF field
strength for several hours or more coincident with the effects of an Earth
directed fast CME.

The solar wind is likely to be at background levels with a possibility of
slightly enhancements through Sunday due to weak coronal hole high speed
stream effects. The geomagnetic field is likely to be quiet with a
possibility of brief unsettled intervals through Sunday due to weak coronal
hole high speed stream effects. CME effects and solar flares strong enough
to affect HF propagation are not likely through Sunday.

Mid-latitude northern hemisphere sunset is now 42 minutes earlier
and daylength is 87 minutes shorter than it was on the June 21st. Daylength
and solar elevation angle in the northern polar region have significantly
declined due to the end of the midnight sun and the approaching equinox.

Click here for today’s Penticton 10.7 cm solar flux index updated at 1700Z,
2000Z and 2300Z daily.

Click here for today’s three-day GFZ Planetary K Index forecast updated
every three hours.

Click here for today's SIDC Daily Bulletin on Solar and Geomagnetic
Activity updated at 1230Z daily.

Click here for today's SWPC Solar Activity Forecast Discussion updated at
0030Z and 1230Z daily.

Click here 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