[RSM] W3LPL forecast thru Tue/31

[Art Boyars]

From: donovanf at erols.com
To: Radio Club <pvrc at mailman.qth.net>
Cc:
Bcc:
Date: Sun, 29 Aug 2021 23:57:21 -0400 (EDT)
Subject: [PVRC] Propagation is likely to be mostly normal through Tuesday
August 31st 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
Tuesday.

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

 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 transitioned 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 with about twice as many
geomagnetically active days compared to June, July, December and January.

 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 sporadic-E 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 about 90 through Tuesday. The
sun’s visible disk has two active regions with 24 mostly small sunspots
generally improving 30 and 20 meter night time propagation and 17 and 15
meter daytime propagation.
*https://sdo.gsfc.nasa.gov/assets/img/latest/latest_1024_0171.jpg
<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 Tuesday. 40 meter short path
propagation to south Asia at about 0000Z is likely to be mostly normal
through Tuesday. 40 meter short path propagation from North America to east
Asia after about 0915Z is likely to be mostly normal through Tuesday.

 30 meter propagation through the auroral ovals and polar regions is likely
to be mostly normal through Tuesday. 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 improve due to
increasing solar ionizing radiation caused by increased sunspot activity.

 20 meter daytime and evening propagation through the auroral ovals and
polar regions is likely to be mostly normal through Tuesday. 20 meter
northern transpolar propagation within a few hours of sunrise and sunset is
likely to improve due to increasing solar ionizing radiation caused by
increased sunspot activity. 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 improve due to increasing solar ionizing
radiation caused by increased sunspot activity.

 17 and 15 meter daytime long distance propagation in the northern
hemisphere is likely to improve due to increasing solar ionizing radiation
caused by increased sunspot activity. 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.

 Solar wind speed is likely to be slightly to moderately enhanced through
Tuesday due to coronal hole high speed stream effects and a chance of a
weak glancing blows by two passing CMEs. The geomagnetic field is likely to
be quiet to unsettled with active periods through Tuesday due to coronal
hole high speed stream effects and a slight chance of a weak glancing blows
by two passing CMEs. There is a slight chance of a minor geomagnetic storm
late Tuesday. Solar flares strong enough to significantly degrade HF
propagation are not likely through Tuesday.

 Mid-latitude northern hemisphere sunset is now 55 minutes earlier and
daylength is 108 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
<http://dx.qsl.net/propagation>* and *http://www.solarham.net
<http://www.solarham.net>*



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