[RSM] W3LPL forecast thru Wed/25

[Art Boyars]

From: donovanf at erols.com
To: PVRC Submissions <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Tue, 24 Aug 2021 01:33:04 -0400 (EDT)
Subject: [PVRC] Normal propagation is likely on Tuesday and mostly normal
on Wednesday August 25th

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 through
Wednesday.

Propagation crossing the auroral ovals and polar regions is likely to be
normal on Tuesday and mostly normal on Wednesday.

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 have 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 with much lower MUFs and
much less  reliable at mid-latitudes in the northern hemisphere during late
August making long distance propagation up to about 8,000 km intermittent
and unreliable in the 17 and 15 meter bands from a few hours after sunrise
until a few hours after sunset.

The solar flux index (SFI) is likely to be 78 or less through
Wednesday. The sun’s visible disk has one small active region with four
small sunspots having a minor effect on HF 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 Wednesday. 40 meter short path
propagation to south Asia at about 0015Z is likely to be normal on Tuesday
and mostly normal on Wednesday. 40 meter short path propagation from North
America to east Asia after about 0930Z is likely to be normal on  Tuesday
and mostly normal on Wednesday.



30 meter propagation through the auroral ovals and polar regions is likely
to be normal on Tuesday and mostly normal on 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 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
longer 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 normal on Tuesday and mostly normal on
Wednesday. 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 longer 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 longer 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 longer nights with no source
of ionizing solar radiation. 17 and 15 meter sporadic-E propagation up to
about 8,000 km is likely to be intermittent, short duration and unreliable
from a few hours after sunrise until a few hours after sunset during 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 near background levels on Tuesday and
moderately enhanced on Wednesday due to coronal hole high speed stream
effects and a weak glancing blow by a passing CME. The geomagnetic field is
likely to be quiet with possible brief unsettled intervals on Tuesday and
quiet to unsettled with likely active intervals late Wednesday due to
coronal hole high speed stream effects and a weak glancing blow by a
passing CME. Solar flares strong enough to affect HF propagation are not
likely through Wednesday.

 Mid-latitude northern hemisphere sunset is now 47 minutes earlier and
daylength is 94 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 autumn
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