[RSM] W3LPL: Below normal... after mid-day Sunday

[Art Boyars]

Another try with reformatted email from W3LPL


Art K3KU/VE4VTR


From: donovanf at erols.com
To: PVRC Reflector <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Fri, 24 Sep 2021 01:48:01 -0400 (EDT)
Subject: [PVRC] Below normal propagation crossing auroral ovals and polar
regions is likely after mid-day Sunday

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 latitudes is likely to be mostly normal through
Sunday.

 Propagation crossing mid latitudes is likely to be mostly normal but with
below normal intervals after mid-day Sunday.

 Propagation crossing the auroral ovals and polar regions is likely to be
mostly normal with below normal intervals then degrading to mostly below
normal after mid-day 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.

 We are in the geomagnetically active autumn equinox season through late
October with about twice as many geomagnetically active days compared to
December, January, June and July caused by the interplanetary magnetic
field (IMF) more frequently persisting in a southward orientation (-Bz).
https://sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_0171.jpg

 The solar flux index (SFI) is likely to be about 90 through Sunday. The
sun’s visible disk has one moderate size active region containing 11 small
to moderate sunspots and three small and tiny active regions containing 24
small and tiny sunspots.

 160 and 80 meter propagation from North America to VK/ZL and the south
Pacific is likely to be mostly normal through Sunday. 40 meter short path
propagation to south Asia at about 0000Z is likely to be mostly normal
through Sunday. 40 meter short path propagation from North America to east
Asia after about 0830Z is likely to be mostly normal through Sunday.

 30 meter propagation through the auroral ovals and polar regions is likely
to mostly normal then degrading to mostly below normal after mid-day
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 nighttime long distance propagation is likely to be
enhanced by increased residual nighttime ionization caused by increased
sunspot activity then mostly below normal after mid-day Sunday due to
increased geomagnetic activity.

 20 meter daytime and evening propagation through the auroral ovals and
polar regions is likely to be mostly normal then degrading to mostly below
normal after mid-day Sunday. 20 meter transpolar propagation within a few
hours of sunrise and sunset is likely to be mostly normal then degrading to
mostly below normal after mid-day Sunday. 20 meter late afternoon,
nighttime and early morning long distance propagation is likely to be
enhanced by increased residual nighttime ionization caused by increased
sunspot activity then mostly below normal after mid-day Sunday due to
increased geomagnetic activity.

 17 and 15 meter daytime long distance propagation is likely to be enhanced
by increased sunspot activity then mostly below normal after mid-day Sunday
due to increased geomagnetic activity.

 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.

 Solar wind speed is likely to be mildly to moderately enhanced on Friday
due to coronal hole high speed stream (CH HSS) effects, slightly enhanced
through mid-day Sunday due to waning CH HSS effects, then much more greatly
enhanced wind speed after mid-day Sunday due to coronal hole high speed
stream and possible CME effects.

 The geomagnetic field (GMF) is likely to be mostly quiet through
mid-day Sunday, with brief unsettled periods early Saturday. The GMF is
likely to be mostly active after mid-day Sunday due to coronal hole high
speed stream effects and a possible CME. A minor geomagnetic storm (G1) is
possible after mid-day Sunday with a slight chance of a brief moderate
geomagnetic storm (G2) if the IMF persists in a southward orientation
(-Bz). Solar flare effects strong enough to significantly degrade HF
propagation are not likely through Sunday.

 Mid-latitude northern hemisphere sunset is 3 minutes earlier and daylength
is 6 minutes shorter than it was on September 22nd. Daytime ionization and
residual nighttime ionization in the northern polar region is steadily
declining following the autumnal equinox.

 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